Arctic Sea Ice : Forum

AGW in general => Consequences => Topic started by: JimD on August 17, 2013, 05:08:37 PM

Title: Sea Level Rise Projections and Maps
Post by: JimD on August 17, 2013, 05:08:37 PM
Thanks to retiredBill I found the link to a global map that shows the effects of different amounts of sea level rise.

There is a global map on which you can set the sea level rise and zoom down to look at specific locations as well as individual maps of prominent cities and locations around the world.  Works just like Google maps.

Specific maps for Florida, New York, Venice, New Orleans, Washington, San Francisco, Nile Delta, Netherlands (it's sad Neven) as well as the global map.

http://geology.com/sea-level-rise/ (http://geology.com/sea-level-rise/)
Title: Re: Sea Level Rise maps
Post by: Anne on August 17, 2013, 05:50:35 PM
It is worth reading Alex Tingle's caveats about his maps here (http://blog.firetree.net/2006/05/18/more-about-flood-maps/). For example he says the source info isn't very accurate, and they don't take account of access to the sea, or of sea defences and erosion.

Bearing all that in mind, it's a thought-provoking resource.
Title: Re: Sea Level Rise maps
Post by: ccgwebmaster on August 17, 2013, 08:42:07 PM
Bearing all that in mind, it's a thought-provoking resource.

One caveat I couldn't see at a glance - the effects of sea level rise from melting land ice vary widely depending on location due to the shifting mass on the planet. Sea level will actually fall near to the big ice sheets as mass is moving away from them - and rise proportionately more further away from them, if memory serves (and this can be a large effect).

In some locations the process is essentially potentially neutral so in those "sweet spots" you can add 10m on to global sea level and not see any significant change. Except in reality the different timings of contributions from different poles is likely to mean nowhere is ultimately unchanged in one direction or another at some point in time.

The specific details with respect to effects at a given location are rather important for planning purposes - if you expect X m of sea level rise (as a global average) by year Y - the implications for what would be needed to defend infrastructure or identify at risk areas are significant.
Title: Re: Sea Level Rise maps
Post by: Ned W on August 18, 2013, 02:07:14 PM
Those maps have been around for a while.  They're not particularly reliable, but do convey the general idea.

They're based on elevation data from the Feb. 2000 Shuttle Radar Topography Mission, which used single-pass radar interferometry to map topography from 56S to 60N.  The resulting product is pretty coarse (spatial resolution 30m within the US, 90m elsewhere) and its vertical accuracy is not great.  In particular, the short wavelength used will tend to result in elevation measurements that are too high (biased upwards) in forested areas. 

Currently, Astrium is working on a much better global elevation data set (World DEM) derived from interferometry using the TerraSAR-X and TanDEM-X satellites.  When it's finished it will be a much better source for this kind of thing, at least in terms of spatial resolution.  I don't know how they're dealing with the problem of biases in forested areas, because TSX and TDX operate at an even shorter wavelength than SRTM did. 

If you really want to assess flood risk at a specific point, you need to look at a much higher resolution and higher accuracy source for topographic data, like airborne lidar.
Title: Re: Sea Level Rise maps
Post by: Ned W on August 18, 2013, 02:14:01 PM
The blog post that Anne links to happens to include what surely must be a candidate for the all-time stupidest comment anywhere:

Quote
Hallo, this is a nice theorie, but the most ice is on the south pole. Greenland was in earlier time ice free! without any change on the sea level. you see, your theorie is bullshit.

That's right.  It turns out that conservation of mass is a CAGW alarmist lie.  You probably believed that if you took all the ice in Greenland and redistributed it across the world's ocean, sea level would have to rise.  But this anonymous blog scientist assures us that once before Greenland's ice just vanished
Title: Re: Sea Level Rise maps
Post by: Anne on August 18, 2013, 03:15:50 PM
You'll find idiot comments all over the place, such as "no accident it's called Greenland", "natural cycles", "you don't need to be a climate scientist to see..." and "who was driving SUVs back in the Eemian?" I'm thinking of starting a collection of these idiocies.  Ned W, that one is a particular gem!
Title: Re: Sea Level Rise maps
Post by: ChrisReynolds on August 20, 2013, 09:19:15 PM
It's not a map but people might want to read the latest RC post:
http://www.realclimate.org/index.php/archives/2013/08/the-inevitability-of-sea-level-rise/ (http://www.realclimate.org/index.php/archives/2013/08/the-inevitability-of-sea-level-rise/)

Bottom line - about 2.3m SLR per degree of warming, long term - i.e. it takes time for ice sheets to respond, so don't get greedy and demand it all immediately. ;)
Title: Re: Sea Level Rise maps
Post by: JimD on August 20, 2013, 09:26:26 PM
Global Flood Damage Could Exceed $1 Trillion Annually by 2050

Interesting reading.  The report (authored by an economist at the World Bank) advocates building seawalls and such.  Note that they get their numbers assuming that sea level has only gone up .2-.4 meters by 2050. 

Just saw Chris's RC post.  Seems like our authors above ought to be advocating for moving those cities instead of trying to build defenses.

Quote
Flood damage in 136 of the world's largest coastal cities could soar to $1tn (£640bn) a year by 2050, because of climate change combined with rapid population increases, economic growth, and subsiding land, according to a study.

The report by Nature Climate Change says the cities at greatest risk, as measured by annual average flood losses, are Guangzhou (China), Miami (US), New York (US), New Orleans (US), Mumbai (India), Nagoya (Japan), Tampa-St Petersburg (US), Boston (US), Shenzen (China) and Osaka-Kobe (Japan).

Owing to their high wealth and low flood protection, Miami, New York and New Orleans comprise 31% of total losses. Adding Guangzhou, the four top cities account for 43% of global losses as of 2005, when the cost of worldwide flood damage was an estimated $6bn a year.

Quote
After all, Hallegatte says, even the cost of massive sea walls, natural barriers, and other coastal protection will seem like chump change compared to a scenario where "we have cities destroyed and we have to rebuild them again and again."

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1979.html (http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1979.html) (paywall)

http://www.theguardian.com/global-development/2013/aug/20/coastal-flood-damage-2050 (http://www.theguardian.com/global-development/2013/aug/20/coastal-flood-damage-2050)

http://www.motherjones.com/environment/2013/08/map-top-cities-billion-dollar-floods (http://www.motherjones.com/environment/2013/08/map-top-cities-billion-dollar-floods)
Title: Re: Sea Level Rise maps
Post by: ritter on August 20, 2013, 10:13:15 PM
Seems like our authors above ought to be advocating for moving those cities instead of trying to build defenses.

Where adaptation fails, migration will have to do. We've never been very good at out engineering nature.  :)
Title: Re: Sea Level Rise maps
Post by: Tor Bejnar on August 20, 2013, 10:19:03 PM
Investtigation of Arctic Sea Level Rise
http://www.whoi.edu/science/PO/arcticsealevel/index.html (http://www.whoi.edu/science/PO/arcticsealevel/index.html)
funded by National Science Foundation and NOAA

An included 2010 presentation is titled
"Arctic Ocean storm surges: origin, climatology, impacts, simulations and predictions".
The summary screen [reformated]:
Quote
* Critical environmental, socioeconomic, and defense issues have focused the people’s attention on the coastal zone.

* This zone is particularly vulnerable in the Arctic, where unprecedented climate changes have already been observed in the context of high natural variability on a range of time scales.

* Key environmental issues affecting human activities on the Alaskan North Slope and Siberian coastal regions include:
     •   coastal erosion,
     •   recent decline in ice extent and thickness,
     •   less stable and predictable shore--‐fast ice, gouging of shelves and coast by sea ice, pile--‐up of ice on shore,
     •   rise in sea level, and storm hazards.

* One element of the observed climate change is the increased frequency and intensity of extreme events.
Title: Re: Sea Level Rise maps
Post by: TerryM on August 20, 2013, 10:42:54 PM
While the costs involved in building a new New York further inland might seem extreme they probably pale when compared to the costs of building ever higher coastal defences. If things progress as rapidly as I fear we would have had to start the project at least a decade ago.
Insurance premiums may rise more rapidly than the sea and corporate head offices may migrate inland faster than the storm surges.
Would Detroit, with it's very low property values, access to plenty of fresh water and possibly an improving climate be seen as viable?
Terry
Title: Re: Sea Level Rise maps
Post by: JimD on August 21, 2013, 05:32:52 PM
Terry

Asking New Yorkers to move to Detroit is almost as cruel as asking them to live in Cleveland!!

And here I was thinking Canadians were nice people.

It does make sense. But the HORROR, it might be better to go down with the ship.
Title: Re: Sea Level Rise maps
Post by: Chuck Yokota on August 21, 2013, 06:22:10 PM
There are some interesting articles about the geographical variations in sea level rise from September 2012:

http://www.skepticalscience.com/Sea-Level-Isnt-Level-This-Elastic-Earth.html (http://www.skepticalscience.com/Sea-Level-Isnt-Level-This-Elastic-Earth.html)

http://www.skepticalscience.com/Sea-Level-Isnt-Level-Ocean-Siphoning-Levered-Continents-and-the-Holocene-Sea-Level-Highstand.html (http://www.skepticalscience.com/Sea-Level-Isnt-Level-Ocean-Siphoning-Levered-Continents-and-the-Holocene-Sea-Level-Highstand.html)
Title: Re: Sea Level Rise maps
Post by: Shared Humanity on August 21, 2013, 08:12:08 PM
While the costs involved in building a new New York further inland might seem extreme they probably pale when compared to the costs of building ever higher coastal defences. If things progress as rapidly as I fear we would have had to start the project at least a decade ago.
Insurance premiums may rise more rapidly than the sea and corporate head offices may migrate inland faster than the storm surges.
Would Detroit, with it's very low property values, access to plenty of fresh water and possibly an improving climate be seen as viable?
Terry

They won't move Manhattan. Concrete perimeter around the island with fill raising the island by about ten feet. You lay all of the underground mechanicals before the fill is put in and lose a couple of stories on each building.
Title: Re: Sea Level Rise maps
Post by: johnm33 on August 25, 2013, 11:06:33 PM
Short of a new topic this looks like the best place for this commentary on a soon to be released IPCC report. http://phys.org/news/2013-08-scientists-revive-climate.html#firstCmt (http://phys.org/news/2013-08-scientists-revive-climate.html#firstCmt)
Title: Re: Sea Level Rise maps
Post by: JimD on August 27, 2013, 07:56:58 PM
John

Good catch.  If you see the report when it comes out please post it.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 01, 2013, 11:06:29 PM
I just edited the title of this topic to include "Projections" of sea level rise.  Wili and I had a series of posts on projection issues a few days ago in another topic and I thought we should have clear topics on things like sea level rise and temperature rises due to the interest in them.  So I thought modifying this topic would be appropriate.  I will look for new links on this issue and insert them.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 01, 2013, 11:38:03 PM
Below is a Jun 2013 paper by Levermann et al (in the Proceedings of the National Academy of Sciences) on the multimillennial sea-level rise due to rising temperatures.

The study gives total projections and projections after 2000 years per degree C rise.  It does not address nearer timeframes, but rather the full rise, and the lower 2000 year rise (in other words it takes more than 2000 years to see the full rise), generated by temperature increases.  It is based on:

Quote
Here we combine paleo-evidence with simulations from physical models to estimate the future sea-level commitment on a multi- millennial time scale and compute associated regional sea-level patterns.

http://www.pnas.org/content/110/34/13745.full (http://www.pnas.org/content/110/34/13745.full)

See especially table 1 as it lists contributions from Greenland, Antarctica and Thermal Expansion and Glaciers - excerpt follows

Rise in M     after 2000yrs          Total Rise
                 Median  Range        Median Range
1 C            2.3       1.0-4.9        2.5     1.0-10.8
   
2 C            4.8        2.6-7.5       10.9    3.1-13.4

3 C            6.6        3.4-9.8       12.5    9.9-14.9

4 C            9.0        5.7-12.1      13.9   11.8-15.9
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 02, 2013, 12:07:58 AM
Below is a Jan 2007 paper by Rahmstorf in Science that makes projections on sea level rise for 2100.  Its primary finding is that for each 1 C rise in temp there will be a sea level rise of 3.4 mm per year.  It projects a sea level rise of up to 1.4 M by 2100.

I note that the paper also says this:
Quote
For this reason, our capability for calculating future sea-level changes in response to a given surface warming scenario with present physics-based models is very limited, and models are not able to fully reproduce the sea-level rise of recent decades.   Rates of sea-level rise calculated with climate and ice sheet models are generally lower than observed rates. Since 1990, observed sea level has followed the uppermost uncertainty limit of the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR), which was constructed by assuming the highest emission scenario combined with the highest climate sensitivity and adding an ad hoc amount of sea-level rise for “ice sheet uncertainty”

The author builds a semi-empirical model and runs hindcasts to check for model validity and then runs it to project future sea level rise.

Quote
We can explore the consequences of this semi-empirical relationship for future sea levels (Fig. 4), using the range of 21st century temperature scenarios of the IPCC (1) as input into Eq. 2. These scenarios, which span a range of temperature increase from 1.4° to 5.8°C between 1990 and 2100, lead to a best estimate of sea-level rise of 55 to 125 cm over this period. By including the statistical error of the fit shown in Fig. 2 (one SD), the range is extended from 50 to 140 cm

Quote
Although a full physical understanding of sea-level rise is lacking, the uncertainty in future sea-level rise is probably larger than previously estimated. A rise of over 1 m by 2100 for strong warming scenarios cannot be ruled out, because all that such a rise would require is that the linear relation of the rate of sea-level rise and temperature, which was found to be valid in the 20th century, remains valid in the 21st century. On the other hand, very low sea-level rise values as reported in the IPCC TAR now appear rather implausible in the light of the observational data.

http://www.sciencemag.org/content/315/5810/368.full (http://www.sciencemag.org/content/315/5810/368.full)
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 02, 2013, 12:27:28 AM
Here is a plain language version of the Levermann paper 2 posts up (by Levermann himself).

I note that Levermann says the current scientific literature puts an upper limit on sea level rise of 2m by 2100.

The long-term (2000 years) sea level rise potential is 2.3m per deg C rise.  And it goes up some more from there.

http://theconversation.com/the-inevitability-of-sea-level-rise-16871 (http://theconversation.com/the-inevitability-of-sea-level-rise-16871)
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 02, 2013, 12:39:52 AM
Another really cool sea level rise map for the US (sorry I love maps).  The map is interactive and you can select states and cities and get a map for the specific city and change all kinds of settings as well.  Very neat!

http://www.climatecentral.org/news/sea-level-rise-locking-in-quickly-cities-threatened-16296 (http://www.climatecentral.org/news/sea-level-rise-locking-in-quickly-cities-threatened-16296)
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 02, 2013, 08:10:37 AM
"Levermann says the current scientific literature puts an upper limit on sea level rise of 2m by 2100."

Yes, but a few scientists, such as Jim Hansen, but also Richard Alley, it seems, do not exclude a possibility of even more than 2m by 2100. Science does not seem to be able to exclude this possibility with high confidence yet, so it seems wise to take such a risk into account in discussions about potential future SLR.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 02, 2013, 08:24:32 AM
Levermann et al speak about a SLR-committment of 2.3 m/degree C over 2000 years.

However, they explicitly take into account a risk of 3m/degree C over 2000 years, and even 4 m/degree C of total SLR-committment over more than 2000 years.

A global temperature rise of 4 degrees C over 2000 years, or even this century, will be very hard to prevent, since earth system sensitivity may be double the fast-feedback sensitivity, so even a 2 degrees rise this century could mean 4 degrees after 2000 years, according to Jim Hansen and others. And Anderson & Bows argue that in many mitigation scenarios even preventing 4 degrees this century has a less than 50% chance of succeeding, so this means we may be on course for up to 8 degrees of warming over 2000 years.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 02, 2013, 04:36:37 PM
Lennart

Quote
Levermann et al speak about a SLR-committment of 2.3 m/degree C over 2000 years.

However, they explicitly take into account a risk of 3m/degree C over 2000 years, and even 4 m/degree C of total SLR-committment over more than 2000 years.

Yes,  from Fig 1 in the paper or my excerpt above:

For 2000 years and a 4C rise in temperature the range is 5.7-12.1m and total rise of 11.8-15.9m.  The range covers the typical uncertainty of the calculations.  Equal chance of the bottom number as the high number. 

Note that the paper DOES NOT indicate that the temperature rise from AGW will be limited to 4C.  The paper was just using the numbers 1-4 for running their model and validating it against past paleo data.  This I believe was just for convenience sake in order to limit the complexity of the work to be done.  If other researchers work comes to the conclusion that temperatures will rise 6 C, for example, one could extrapolate from this papers work or, better yet, rerun their model using 6C and recalculate new numbers.

I'm sure that if other researchers find this paper sound there will be other work leveraged from it and we will get new calculations in the next few years.

As not to many people are really focused on what happens in 2000 years but want to know what is going to happen soon (by 2100) we will need to find some other papers to insert as well.

Feel free to insert academic papers on this topic as you find them.  A lot of commentators and bloggers have come up with number via their own interpretations of what they read and hear, and those are interesting as well because it is instructive to follow their logic and also to see what concerns them the most.  But I always want to see the original work myself (I am not very trusting) as people have a tendency to exaggerate or change the intent of the original work.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 02, 2013, 05:45:01 PM
Thanks to AbruptSLR and Lennart I found over in the Antarctic Folder another link to a paper on SLR by Goelzer et al Jul 2012

Quote
Millennial total sea-level commitments projected with the Earth system model of intermediate complexity LOVECLI


http://iopscience.iop.org/1748-9326/7/4/045401/article (http://iopscience.iop.org/1748-9326/7/4/045401/article)

The following is the projection from the abstract:

Quote
... In experiments with greenhouse gas concentration stabilization at 2100 AD, the total sea-level rise ranges between 2.1 m (B1), 4.1 m (A1B) and 6.8 m (A2). In all scenarios, more than half of this amount arises from the Greenland ice sheet, thermal expansion is the second largest contributor, and the contribution of glaciers and ice caps is small as it is limited by the available ice volume of maximally 25 cm of sea-level equivalent....

BIG NOTE:  This paper is projecting for the date year 3000 vice 4000 (or more) as in the Levermann paper.  It could be that the numbers from the 2 papers are in very close agreement.

They are using the IPCC scenarios and assuming greenhouse gas concentrations stabilize.  The approximate (I am eyeballing a chart) CO2 concentrations year 2100 for the scenarios are (B1) 530ppm, (A1B) 700ppm, (A2) 830ppm. 

Any more educated readers want to inform us on this a bit on these papers?  I note that the climate sensitivity used in the LOVECLIM is much lower than what seems to be the consensus sensitivity numbers used elsewhere (but maybe this makes sense in what they are doing for some reason).  The paper also states (I think) that for the 1000 year timeframe of this study that Greenland dominates in terms of ice sheet melting over Antarctica and that a little more than 50% of  Greenland will be melted by then (this is the A2 scenario and +6C temperature rise).
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 02, 2013, 10:17:16 PM
Jim,

You're right that for every worst-case scenario there's also a best-case scenario. From a precautionary perspective I think scientifically based worst-case scenarios should be leading in deciding about policies, so that's why I think we should stress those worst-case scenarios, while hoping the best-case scenarios, or even the most likely scenarios, will turn out to be more/most accurate.

Goelzer et al 2012 I find interesting because it seems they find a worst-case scenario of about 25 meters of SLR by the year 3000, if I interpret their figure 7 correctly.

I will soon post some other SLR-articles I find interesting.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 03, 2013, 12:36:08 AM
Here is a Vermeer and Ramstorf paper (published in PNAS) from 2009 that projects sea level for a number of IPCC scenarios.  It is interesting to compare this with the other Ramstorf paper above from 2007.  Using different methodology slightly higher numbers are projected in this paper (approx. 0.5m higher) 75 to 190 cm.

Quote
Global sea level linked to global temperature
Martin Vermeera,1 and Stefan Rahmstorfb
aDepartment of Surveying, Helsinki University of Technology, P.O. Box 1200, FI-02150, Espoo, Finland; and bPotsdam Institute for Climate Impact Research, Telegrafenberg A62, 14473 Potsdam, Germany
Edited by William C. Clark, Harvard University, Cambridge, MA, and approved October 26, 2009 (received for review July 15, 2009 


http://www.pnas.org/content/106/51/21527.full (http://www.pnas.org/content/106/51/21527.full)

Quote
Abstract

We propose a simple relationship linking global sea-level variations on time scales of decades to centuries to global mean temperature. This relationship is tested on synthetic data from a global climate model for the past millennium and the next century. When applied to observed data of sea level and temperature for 1880–2000, and taking into account known anthropogenic hydrologic contributions to sea level, the correlation is >0.99, explaining 98% of the variance. For future global temperature scenarios of the Intergovernmental Panel on Climate Change's Fourth Assessment Report, the relationship projects a sea-level rise ranging from 75 to 190 cm for the period 1990–2100.
Quote

Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 03, 2013, 01:13:57 AM
Here is a very interesting paper that was referenced in the 2009 Ramstorf paper.

Pheffer et al Sep 2008 Science
Kinematic Constraints on Glacier Contributions to 21st-Century Sea-Level Rise

http://www.sciencemag.org/content/321/5894/1340.full?sid=4f90482f-93da-43bf-b786-7200292dc236 (http://www.sciencemag.org/content/321/5894/1340.full?sid=4f90482f-93da-43bf-b786-7200292dc236)

This paper is a very interesting read (and a relatively easy one as there is basically no math in it).  The basic conclusion of the paper is that sea level rises above 2 M by 2100 are not physically tenable.  Greenland due to its geology is amenable to calculating with some certainty its possible slr contributions but Antarctica is not for the same reason.  The paper assumes East Antarctica just will not have significant changes by 2100 so it will not contribute much to slr while in the west the authors make their calculation (if I understand it correctly) assuming high end observed processes (glacier speeds and such).  For Antarctica to change the 2 M number (it is impossible for Greenland to do this) there would have to be a significant and large change in the dynamics of the melt down there.  Maybe AbruptSLR could jump in and respond to this paper as I am sure he has read it and he is very technically astute.

Quote
Abstract

On the basis of climate modeling and analogies with past conditions, the potential for multimeter increases in sea level by the end of the 21st century has been proposed. We consider glaciological conditions required for large sea-level rise to occur by 2100 and conclude that increases in excess of 2 meters are physically untenable. We find that a total sea-level rise of about 2 meters by 2100 could occur under physically possible glaciological conditions but only if all variables are quickly accelerated to extremely high limits. More plausible but still accelerated conditions lead to total sea-level rise by 2100 of about 0.8 meter. These roughly constrained scenarios provide a “most likely” starting point for refinements in sea-level forecasts that include ice flow dynamics.
Title: Re: Sea Level Rise Projections and Maps
Post by: Laurent on September 03, 2013, 10:27:27 AM
Watching Antartic melting last winter (Northen), I can tell you, it started to melt, not a lot but yes it did. I am not speaking of Ronne ice shelve and Filchner Ice shelve wich did melt a lot but of amery ice shelve. Abruptslr  will tell us more... !
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 03, 2013, 10:44:49 AM
Hansen & Sato 2011 (draft version that was published unchanged in 2012) on pp.22-23 give the following comment on Pfeffer et al 2008:
http://arxiv.org/ftp/arxiv/papers/1105/1105.0968.pdf (http://arxiv.org/ftp/arxiv/papers/1105/1105.0968.pdf)

“The kinematic constraint may have relevance to the Greenland ice sheet, although the assumptions of Pfeffer at al. (2008) are questionable even for Greenland. They assume that ice streams this century will disgorge ice no faster than the fastest rate observed in recent decades. That assumption is dubious, given the huge climate change that will occur under BAU scenarios, which have a positive (warming) climate forcing that is increasing at a rate dwarfing any known natural forcing. BAU scenarios lead to CO2 levels higher than any since 32 My ago, when Antarctica glaciated. By mid-century most of Greenland would be experiencing summer melting in a longer melt season. Also some Greenland ice stream outlets are in valleys with bedrock below sea level. As the terminus of an ice stream retreats inland, glacier sidewalls can collapse, creating a wider pathway for disgorging ice.

The main flaw with the kinematic constraint concept is the geology of Antarctica, where large portions of the ice sheet are buttressed by ice shelves that are unlikely to survive BAU climate scenarios. West Antarctica's Pine Island Glacier (PIG) illustrates nonlinear processes already coming into play. The floating ice shelf at PIG's terminus has been thinning in the past two decades as the ocean around Antarctica warms (Shepherd et al., 2004; Jenkins et al., 2010). Thus the grounding line of the glacier has moved inland by 30 km into deeper water, allowing potentially unstable ice sheet retreat. PIG's rate of mass loss has accelerated almost continuously for the past decade (Wingham et al., 2009) and may account for about half of the mass loss of the West Antarctic ice sheet, which is of the order of 100 km3 per year (Sasgen et al., 2010).

PIG and neighboring glaciers in the Amundsen Sea sector of West Antarctica, which are also accelerating, contain enough ice to contribute 1-2 m to sea level. Most of the West Antarctic ice sheet, with at least 5 m of sea level, and about a third of the East Antarctic ice sheet, with another 15-20 m of sea level, are grounded below sea level. This more vulnerable ice may have been the source of the 25 ± 10 m sea level rise of the Pliocene (Dowsett et al., 1990, 1994). If human-made global warming reaches Pliocene levels this century, as expected under BAU scenarios, these greater volumes of ice will surely begin to contribute to sea level change. Indeed, satellite gravity and radar interferometry data reveal that the Totten Glacier of East Antarctica, which fronts a large ice mass grounded below sea level, is already beginning to lose mass (Rignot et al., 2008).”

My conclusion from Hansen and Sato is that it may be too early to say with high confidence that more than 2m of SLR by 2100 is not possible.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 03, 2013, 05:25:17 PM
Another interesting paper is Foster & Rohling 2013 in PNAS:
http://www.pnas.org/content/early/2013/01/03/1216073110.full.pdf+html (http://www.pnas.org/content/early/2013/01/03/1216073110.full.pdf+html)

They conclude:
"Given the present-day (AD 2011) atmospheric CO2 concentration of 392 ppm, we estimate that the long-term sea level will reach +24 +7/−15 m (at 68% confidence) relative to the present. This estimate is an order of magnitude larger than current projections for the end of this century [up to 2 m; best estimate, 0.8 m (Pfeffer et al. 2008)] and seems closer to the worst-case long-term sea level projection portrayed by Meehl et al. (2012). Using terminology of the Intergovernmental Panel on Climate Change Fourth Assessment Report IPCC AR4, we find it very likely (i.e., at 90% confidence) that long-term sea-level rise for sustained present-day CO2 forcing will be >6 m, and likely (68% confidence) that it will be >9 m. Through analogy with the geological record, this rise likely will be achieved through melting of the GrIS and WAIS and possibly some portion of the EAIS (if sea level were to rise >14 m). However, it will take many centuries to get to these high levels. Given the typical mean rates of natural sea-level rises on multicentury timescales [1.0–1.5 cm·yr−1, with extremes during deglaciation of 5 cm·yr−1], our projection suggests an expected equilibration time of the Earth system to modern CO2 forcing of 5–25 centuries."

So they think the current CO2-concentration of almost 400 ppm will eventually, in about 5-25 centuries, lead with 68% likelihood to a SLR of 9-31m, with a best estimate of about 24m, and with 84% likelihood of at least 9m of eventual SLR (their 68% in this case is not 'carefully worded', as Rohling has confirmed by email).

Even for 350 ppm they find a 84% chance of at least 7m of SLR in the longer term, with a best estimate of about 16m, and 16% chance of more than 21m (according to supporting information file Dataset S2, linked at the end of the supplementary information).
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 03, 2013, 05:34:04 PM
Meehl et al 2012 (Nature Climate Change), to which Foster & Rohling 2013 refer, contains this interesting figure:
http://www.nature.com/nclimate/journal/v2/n8/fig_tab/nclimate1529_F3.html (http://www.nature.com/nclimate/journal/v2/n8/fig_tab/nclimate1529_F3.html)

This seems to imply a worst-case scenario of almost 6m of SLR by 2200 and about 10-12m by 2300.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 03, 2013, 05:36:18 PM
Quote
My conclusion from Hansen and Sato is that it may be too early to say with high confidence that more than 2m of SLR by 2100 is not possible.

I don't think anyone is saying that other than that is the conclusion of the Pheffer paper.  While Hansen does not seem to like the paper, Ramstorf seems to have the opposite opinion.  But a good find and interesting comments.

One thing I find disappointing about the Hansen paper is that, in some ways, it seems to misrepresent the Pheffer paper or ignore the contents of the paper.  Pheffer went to some trouble to show why the topography of Greenland significantly restricts the flow of ice into the sea and calculates how much higher the rate of ice movement and melt would have to be to result in large contributions to sea level rise and concludes that it is not possible.  This seems to take into account Hansen's argument.  I would have preferred him to state why Pheffers calculations and conclusions are wrong rather than just to say the melt is going to rapidly accelerate and this  will overcome the geology.

Quote
...The present-day average velocity of all Greenland outlet glaciers is 0.56 km/year when weighted by drainage basin area or 1.23 km/year when weighted by gate cross-sectional area. The two weighted averages are different because gate cross-sectional area does not scale with drainage basin area. Average (present day to 2100) outlet glacier speeds required to meet 2- and 5-m SLR targets range from 26.8 km/year to 125 km/year, depending on the scenario considered [table 2 and supporting online material (SOM)]. These velocities must be achieved immediately on all outlets considered and held at that level until 2100. Delays in the onset of rapid motion increase the required velocity further (fig. S1)...
....A comparison of calculated (Table 2) and observed (1.23 km/year) average velocities shows that calculated values for a 2-m SLR exceed observations by a factor of 22 when considering all gates and inflated SMB and by a factor of 40 for the marine gates without inflated SMB, which we consider to be the more likely scenario. With the exception of discharge through all gates at inflated SMB (26.8 km/year), none of the velocity magnitudes shown in Table 2 has ever been observed anywhere, even over short time periods....

The Pheffer paper seems to assume (or maybe it said it) that the Eastern Antarctic will not make any significant contributions to sea level rise this century (which I seem to have read in other places as well).  The Paper indicates that over 90% of the Antarctic contribution to slr will come from PIGS/Thwaites and Lambert/Amery.  Once again the Pheffer paper seems to anticipate the Hansen papers arguments for Antarctic melt and after reading the Hansen comments several times Hansen does not exactly refute the Pheffer papers timeline.  He just seems to state that there will eventually be a very large melt from the West side.  The Pheffer paper says this about this area:
 
Quote
Most of the marine-based ice in West Antarctica is held behind the Ross and Filchner-Ronne ice shelves, which we consider unlikely to be removed by climate or oceanographic processes within the next century [e.g., (19)]. The Amundson Coast basin [including Pine Island Glacier (PIG) and Thwaites Glacier], however, is not confined by large ice shelves and contains about 1.5 m sea level equivalent (5.43 × 105 Gt) (20). The aggregate cross-sectional gate area of PIG and Thwaites Glacier is ca. 120 km2 (20). The average velocity in this region is 2 km/year (table S2), higher than the average velocity of all Antarctic ice streams [0.65 km/year (19)]. An average (present day to 2100) velocity of 53.6 km/year is required to discharge 1.5 m sea-level equivalent through the PIG and Thwaites glacier gates by 2100, again far greater than any observed glacier velocity. ...


Anyway, this is interesting and I am learning a lot.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 03, 2013, 05:42:46 PM
What I forgot to note in my last post: even the strongest mitigation scenario of Meehl et al 2012 seems to contain a risk of more than 1m of SLR by 2100 and more than 3m by 2300.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 03, 2013, 05:52:01 PM
Meehl et al 2012 (Nature Climate Change), to which Foster & Rohling 2013 refer, contains this interesting figure:
http://www.nature.com/nclimate/journal/v2/n8/fig_tab/nclimate1529_F3.html (http://www.nature.com/nclimate/journal/v2/n8/fig_tab/nclimate1529_F3.html)

This seems to imply a worst-case scenario of almost 6m of SLR by 2200 and about 10-12m by 2300.

I tried to find a non-paywalled copy of this paper and could not unfortunately.  If anyone finds one please post it. 

I notice on the graphs from the paper you linked to that it is in pretty close agreement with the Pheffer paper.  It seems that Ramsdorf, Pheffer, Levermann and Meehl and their co-authors are in, at least, broad agreement given their different approaches.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 03, 2013, 05:54:04 PM
Jim, good points about Pfeffer et al and Hansen & Sato. I've looked at those before, but am not yet entirely convinced. I have to run now, but will come back and see if I can explain why Hansen & Sato may still have a point about Pfeffer et al, although I agree it needs more careful and elaborate work to be able to be really convincing.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 03, 2013, 08:07:38 PM
Jim,

You can find a lot of relevant discussion and papers on the risks of SLR in this thread (and also others) in the Antarctic folder, where AbruptSLR has done, and still is doing, a great job in pointing out reasons why Pfeffer et al 2008 may still be underestimating those risks:
http://forum.arctic-sea-ice.net/index.php?topic=31.0 (http://forum.arctic-sea-ice.net/index.php?topic=31.0)

See for example this comment I made there:

"Pfeffer et al (2008) estimate a max possible rise of about 2 meters by 2100:
http://www.sciencemag.org/content/321/5894/1340.full.pdf (http://www.sciencemag.org/content/321/5894/1340.full.pdf)

That would imply a rate of SLR by about 2100 of probably circa 4 cm/yr, so if sustained about 4 m/century. The question is if this would be their estimated max potential rate of SLR, or if it could go even faster later in the next century.

Hansen and Sato (2012) seem to expect an 'iceberg cooling' negative feedback which would keep the max rate of SLR under about 5-6 meters/century (under BAU emissions). They criticize Pfeffer et al for (mainly) not sufficiently taking the instablity of WAIS into account.

Pfeffer et al assume an average outlet glacier velocity for PIG/Thwaites of about 14-15 km/yr from 2020-2100. How fast could we reach that speed and how much faster could those glaciers go?

And how about the assumption of Pfeffer et al for Greenland of an average outlet glacier velocity of about 27 km/yr from 2020-2100? How likely is that and how much faster could it go, if at all?"

Also Pfeffer et al did not consider a possible contribution from Totten Glacier in the EAIS, if I'm not mistaken.

And they assume a sudden speed-up of all outlet glaciers until 2020 with constant speed from then on. But could this acceleration not continue for several more decades?

About the possible 'iceberg cooling effect' that Hansen & Sato point out: they speak of a model run of 60 cm of SLR by 2065 and 1.4m by 2080, so assuming constant speed from then on this would imply almost 2.5m by 2100, about 8m by 2200 and about 13.5m by 2300 as a worst-case scenario.

This would be only a little more extreme than Pfeffer et al and Meehl et al. whose worst-case scenarios would reach these same levels only a few decades later. This would seem to make little difference for potential mitigation and adaptation policy implications in the current decade and the rest of this century.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 03, 2013, 09:18:32 PM
I found an interesting letter in PNAS by Strauss Jul  2013 that comments on the Levermann paper.

One item especially caught my attention.  Great numbers for use in promoting awareness of our problems.  The total melting potential of burning a ton of coal or a liter of petroleum.

Quote
One more set of implications from Levermann et al. is worth visiting here. Simple calculations integrating TCRE indicate that emitting 1 metric ton of carbon may increase ocean volume by 1,092 m3 (588– 1680 m3) in the long run. Similarly, combusting 1 ton of coal ultimately adds 621 m3 (334–955 m3) to the ocean, and a single liter of petroleum adds 647 times its volume (348– 996 L), assuming mean fuel carbon densities from current US consumption (16).





http://www.climatecentral.org/wgts/filetracker.php?file2dl=Strauss-PNAS-2013.pdf (http://www.climatecentral.org/wgts/filetracker.php?file2dl=Strauss-PNAS-2013.pdf)
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 03, 2013, 10:10:13 PM
Lennart

BTW I am just having fun here looking through the papers and trying to figure out what they say.  I have no position on what the right answer is.  I am playing devil's advocate is all and not picking any fights.

Quote
And how about the assumption of Pfeffer et al for Greenland of an average outlet glacier velocity of about 27 km/yr from 2020-2100? How likely is that and how much faster could it go, if at all?"

I think you misunderstood this paragraph from the paper.
Quote
The present-day average velocity of all Greenland outlet glaciers is 0.56 km/year when weighted by drainage basin area or 1.23 km/year when weighted by gate cross-sectional area. The two weighted averages are different because gate cross-sectional area does not scale with drainage basin area. Average (present day to 2100) outlet glacier speeds required to meet 2- and 5-m SLR targets range from 26.8 km/year to 125 km/year, depending on the scenario considered [table 2 and supporting online material (SOM)]. These velocities must be achieved immediately on all outlets considered and held at that level until 2100. Delays in the onset of rapid motion increase the required velocity further (fig. S1).

Current weighted speed is only 1.23 km/yr and the speed needed to hit a 2m slr is 26.8 km/yr.  And that 26.8 km/yr would have to be achieved immediately and held at that speed until 2100.  Any delays in getting to this speed immediately require even higher velocities.  I surely do not know how likely it is that we will hit the 26.8 nor if higher speeds are possible (we would have to find it in some other paper), but I absolutely know that we will not be hitting the 26.8 km/yr speed for many years yet.  The melt just does not have enough heat driving it yet and will not for some time.  So, if we accept their numbers it means that the velocity needed will be well in excess of the 26.8 km/yr.  Greenland seems to be constrained.

Quote
Also Pfeffer et al did not consider a possible contribution from Totten Glacier in the EAIS, if I'm not mistaken.
I think this is correct as Totten is not specifically mentioned.  In the chart on Antarctic contributions to slr it does not look like the East Antarctic is listed, but I may just be misinterpreting it also.

Quote
Pfeffer et al assume an average outlet glacier velocity for PIG/Thwaites of about 14-15 km/yr from 2020-2100. How fast could we reach that speed and how much faster could those glaciers go?

Well that is the question all right and the answer seems to hang on it.  The paper says this

Quote
The average velocity in this region is 2 km/year (table S2), higher than the average velocity of all Antarctic ice streams [0.65 km/year (19)]. An average (present day to 2100) velocity of 53.6 km/year is required to discharge 1.5 m sea-level equivalent through the PIG and Thwaites glacier gates by 2100, again far greater than any observed glacier velocity

which indicates that the current PIGS/Thwaites velocity is 2 km/yr and then the paper calculates its 2m by 2100 limit based upon an increase in PIGS/Thwaites velocity of 7 times.  A big increase so they are assuming it speeds up a lot.  And it has to hit that velocity within 10 years and then hold.  Is this assumption still too conservative?  I have no idea but they do seem to be fully accepting that all melt rates are going to increase significantly.  To fully dump PIGS/Thwaite would require an immediate speed up of 26 times the current velocity that held till 2100.  Close to a collapse?  One of our Black Swans perhaps?

Quote
And they assume a sudden speed-up of all outlet glaciers until 2020 with constant speed from then on. But could this acceleration not continue for several more decades?

I may be exceeding my pay grade here, but I think the answer to that question is no for Greenland and for the Antarctic maybe.  The outlet glaciers do not have an unlimited amount of ice to dump into the ocean.  As time goes on they will have dumped a large percentage of the total volume of ice available to them and the rate of new ice creation will eventually come to a halt due to the warming.  Greenland is constrained due to it being shaped like a bowl.  As the depth of the ice cap shrinks it has less force to exert, less volume to dump and, importantly, less height advantage.  Antarctica obviously is shaped more traditionally and also has a lot more volume to dump.  How fast it could go, how soon it could get up to speed and how long it could last?  Good question.  I expect that if there are any significant flaws in the paper or omissions it will be in relation to Antarctica.  But, excepting the unexpected collapse (to everyone but AbruptSLR) it would seem unlikely that we will get an acceleration there for many years yet, so this paper might be pretty on the mark?  Maybe??
   
There is a supplemental table to the paper (separate pdf download) which details all the main discharging glaciers in Greenland that might help understand how detailed this paper was in those calculations.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 03, 2013, 10:51:26 PM
I'm still wondering how Levermann et al compares to Foster & Rohling. F&R think that 400 ppm is enough to raise sea level by about 10-30m in the long run. Let's assume 400 ppm implies about 2-4 degrees C of warming in the long run. So F&R's estimate then suggests about 2.5-15m of SLR per degree of warming in the long run, a much wider range than the circa 3-4m per degree of Levermann et al (for 4 degrees of warming).

So do Levermann et al under-estimate potential SLR for the long run? Or do Foster & Rohling over-estimate this potential long-run SLR?
Title: Re: Sea Level Rise Projections and Maps
Post by: TerryM on September 03, 2013, 11:58:07 PM
Probably a very stupid question but is it possible that the ice/ocean interface will move sufficiently far inland that the only thing passing through the narrow cracks in the bowl's edge will be meltwater?
If glacial retreat exceeds glacial advance this would at some point seem an inevitability but I don't know if there are examples of this kind of activity re. ice sheets. Mountain glaciers are in retreat everywhere you look & if the same process took place with ice sheets in Greenland wouldn't this throw out all the papers that are based on glaciers entanglements in the narrow fjords that snake their way through coastal mountains?
Terry
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 04, 2013, 12:02:20 AM
Jim,

I greatly appreciate your detailed comments on Pfeffer et al. Here's another link to their paper, since the other links may not work:
http://www3.geosc.psu.edu/~jfk4/Geosci_500/Discussion%20papers/Last%20week%202/Science%202008%20Pfeffer.pdf (http://www3.geosc.psu.edu/~jfk4/Geosci_500/Discussion%20papers/Last%20week%202/Science%202008%20Pfeffer.pdf)

They may very well be right, but I'm also playing a kind of devil's advocate, since we want to have very high confidence in their conclusions in order to not be (even more) unpleasantly surprised later on.

So let's consider these quotes from their paper:

"[T]he near-doubling of ice discharge from Jakobshavn Glacier in 2004–2005 was associated with an acceleration to 12.6 km/year (7). Similarly, a temporary 80% increase in the speed near the terminus of Kangerdlugssuaq produced a velocity of 14.6 km/year (6). A comparison of calculated (Table 2) and observed (1.23 km/year) average velocities shows that calculated values for a 2-m SLR exceed observations by a factor of 22 when considering all gates and inflated SMB and by a factor of 40 for the marine gates without inflated SMB, which we consider to be the more likely scenario. With the exception of discharge through all gates at inflated SMB (26.8 km/year), none of the velocity magnitudes shown in Table 2 has ever been observed anywhere, even over short time periods.
The highest observed velocities have occurred at surging glaciers, including circa (ca.) 70 m/day (25.5 km/year) at Variegated Glacier (17) and 105 m/day (38.3 km/year) at Medvezhiy Glacier (18), but were held only for brief periods (hours to days). Although no physical proof is offered that the velocities given in Table 2 cannot be reached or maintained over century time scales, such behavior lies far beyond the range of observations and at the least should not be adopted as a central working hypothesis."

"Greenland SMB was accelerated at present-day rates of change, but dynamic discharge was calculated by accelerating outlet glacier velocities by an order of magnitude in the first decade. In Antarctica, PIG/Thwaites was accelerated from present-day net discharge (19) in the first decade and held thereafter to the highest outlet glacier velocity observed anywhere [14.6 km/year (6)], and Lambert/Amery was accelerated from present-day net discharge (19) in the first decade by an order of magnitude and held thereafter."

"Most of the marine-based ice in West Antarctica is held behind the Ross and Filchner-Ronne ice shelves, which we consider unlikely to be removed by climate or oceanographic processes within the next century [e.g., (19)]."

Fair enough, that it seems I confused their 27 km/yr average speed from 2008-2100 for 2m SLR by GIS alone with their circa 12 km/yr average speed over 2020-2100 for the GIS-contribution to a total 2m SLR by 2100. So the first seems indeed very unlikely, but the second maybe not completely, since such velocities have already been observed in a few locations/short periods and it seems the melting has just begun and has speeded up quite a bit over the past decade?

Moreover, GIS may be more vulnerable than thought at Jakobshavn and Petermann Glaciers, since at these glaciers the glacier beds extend inland hundreds of kilometers below sea level into the interior, as Hansen & Sato also seem to indicate?

Pfeffer et al do consider a contribution from Amery/Lambert in the EAIS, but a much larger part of EAIS may be vulnerable to relatively mild warming, according to recent research on the Pliocene (I don't have the reference at hand now, but it will be in the Antarctic thread for sure).

The great ice shelves RIS and FRIS may also be more vulnerable than thought, but I will have to check what papers AbruptSLR has found on those.

To what extent negative and positive melting feedbacks will balance each other out or not seems to still be an open question as well.

Pfeffer himself has given a nice overview in 2011 of the state of the science on land ice and sea level rise:
http://www.tos.org/oceanography/archive/24-2_pfeffer.pdf (http://www.tos.org/oceanography/archive/24-2_pfeffer.pdf)

He says:

'[M]uch of the focus of the glaciological research community has been on the dynamics of marine-based ice—that is, on the possibility of “rapid dynamic changes” that would transfer ice quickly from land to ocean and raise sea level far faster than by melt alone. Such events appear in the PDF as a “Fat Tail”: events of high consequence, and low but not a vanishing probability, hence, the “fat” tail of the distribution. Such events are both spectacular and important, but they are not the entire story, nor are
they the entire PDF.'

So my conclusion so far is: 2m of SLR by 2100 seems quite unlikely, but we cannot at this moment exclude such a risk, and there might even be a reasonable argument in the making for a risk of still faster SLR.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 04, 2013, 12:07:22 AM
Terry,

I've been wondering the same, but have found no answer yet. I suspect/fear however that Arctic amplification will have some big unpleasant suprises in store for us when GIS, WAIS and EAIS start to melt/disintegrate seriously later this century.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 04, 2013, 12:14:10 AM
Expert elicitation seems to be an important way of getting more insight into the potential risk of WAIS-collapse. Bamber & Aspinall (2013) gave some useful data from their survey amongst 13 experts (out of 26 invited) in 2010 and 2012:
http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1778.html (http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate1778.html)

In their supplementary Table S1 (p.8 last column) they apparently show that the rate of SLR in 2100 from the ice sheets is estimated on average to be 5-7 mm/yr, with a 5% risk of more than circa 17 mm/yr, and a very small chance of almost 4 cm/yr in the most extreme scenario. That last scenario would seem to be about the same as the most extreme scenario by Pfeffer et al. On p.10 (bottom) of the supplementary info they also seem to give an even more extreme estimate for the max rate of (total) SLR in 2100 of almost 5 cm/yr, but I don't understand the technical details of these different estimates.

The 13 experts surveyed were (p.11 supplementary info):
Richard Alley, Richard Hindmarsh, Philippe Huybrechts, Ian Joughin, Shawn Marshall, Frank Pattyn, Jeff Ridley, Eric Rignot, Catherine Ritz, Robert Thomas, Michiel van den Broeke, Roderik van de Wal, David Vaughan.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 04, 2013, 01:09:57 AM
Lennart

In an attempt to shed some light on this question.

So do Levermann et al under-estimate potential SLR for the long run? Or do Foster & Rohling over-estimate this potential long-run SLR?

I found two articles on RealClimate on this very question of process based, empirical based and paleo based sea level projections by Ramsdorf.  Pretty convenient.  I am still trying to process the articles and all the comments.  Let me know what you think.

Part 1
http://www.realclimate.org/index.php/archives/2013/01/sea-level-rise-where-we-stand-at-the-start-of-2013/ (http://www.realclimate.org/index.php/archives/2013/01/sea-level-rise-where-we-stand-at-the-start-of-2013/)

Part 2
http://www.realclimate.org/index.php/archives/2013/01/sea-level-rise-where-we-stand-at-the-start-of-2013-part-2/ (http://www.realclimate.org/index.php/archives/2013/01/sea-level-rise-where-we-stand-at-the-start-of-2013-part-2/)
Title: Re: Sea Level Rise Projections and Maps
Post by: AbruptSLR on September 04, 2013, 03:14:33 AM
All,

I have found the discussion in this thread enjoyable.  Unfortunately, I do not have time now to properly entering into the discussion about Pfeffer et al 2008/2011; so I will provide the following link to so of my prior comments on this topic (of Pfeffer et al), and I would like to draw particular attention to my reply #19 in that thread that indicates that all of the researchers cited after the link will be holding a seminar (September 9-12, 2013) to consider whether there is justification to increase SLR projections beyond that considered essentially by Pfeffer et al (ie over 7-ft or 2.1 m by 2100).  Thus I am not the only person concerned with this possibility:

http://forum.arctic-sea-ice.net/index.php/topic,70.0.html (http://forum.arctic-sea-ice.net/index.php/topic,70.0.html)


Louise C. Biddle - University of East Anglia; Carmen Boening – JPL; Knut Christianson - New York University; Ian Fenty – JPL; Ichiro Fukumori – JPL; Karen J. Heywood - University of East Anglia; David M. Holland - New York University; Chia-Wei Hsu - University of California, Irvine; Erik R. Ivins – JPL; Ian R. Joughin - University of Washington; Ala Khazendar – JPL; Ron Kwok – JPL; Felix W. Landerer – JPL; Eric Yves Larour – JPL; Brent M. Minchew – Caltech; Sophie MJ Nowicki - NASA GSFC; Antony J. Payne - University of Bristol; Eric Rignot - University of California, Irvine; Mirko Scheinert - Dresden University of Technology; Michael Schodlok – UCLA; Mark Simons – Caltech; Andrew L. Stewart – Caltech; Andrew F. Thompson – Caltech; Isabella Velicogna - University of California Irvine; Anna K. Wahlin - University of Gothenburg; Michael M. Watkins – JPL; Benjamin G. Webber - University of East Anglia; Josh Willis - JPL

Furthermore, I would like to make a very few quick comments about Pfeffer et al's case:
(1) Their values for current ice mass loss from the WAIS need to be increased by about 25% due to Glacial Isostatic Adjustment, GIA, corrections to match recent GPS field measurement (and if one were to follow their logic this would increase the 2100 SLR contribution from the WAIS also by 25%).
(2) They do not realize that substantial amount of ice mass loss from the AIS currently occurs due to the outflow of basal melt water, see the attached table from:

Citation: Death, R., Wadham, J. L., Monteiro, F., Le Brocq, A. M., Tranter, M., Ridgwell, A., Dutkiewicz, S., and Raiswell, R.: Antarctic Ice Sheet fertilises the Southern Ocean, Biogeosciences Discuss., 10, 12551-12570, doi:10.5194/bgd-10-12551-2013, 2013.

http://www.biogeosciences-discuss.net/10/12551/2013/bgd-10-12551-2013.pdf (http://www.biogeosciences-discuss.net/10/12551/2013/bgd-10-12551-2013.pdf)

http://www.biogeosciences-discuss.net/10/12551/2013/bgd-10-12551-2013-supplement.pdf (http://www.biogeosciences-discuss.net/10/12551/2013/bgd-10-12551-2013-supplement.pdf)

(3) They seem to ignore the fact that as the WAIS is the last remaining marine ice sheet, most of the ice mass loss after 2040 will likely occur by the float-out of icebergs and bergy bits that have calved-off of the unstable faces of several ice streams that have retreated behind the gateways cited by Pfeffer et al.

When, I have more time I will post more arguments for why Pfeffer et al 2008/2011 may be non-conservative, from a public safety point of view (or if you have the energy you could look though the many threads in the Antarctic folder).

Best,
ASLR
Title: Re: Sea Level Rise Projections and Maps
Post by: AbruptSLR on September 04, 2013, 05:07:01 AM
I only have time to make short replies for a while about why an upper SLR limit by 2100 beyond Pfeffer et al's 2m value should be considered:

Regarding my prior comment that possibly after 2040 bergy bits (particularly from Thwaites, Smith and Pine Island, Glaciers) may calve-off and float away faster than Pfeffer et al considered, see particularly my replies #13 and 46 at the following thread link:

http://forum.arctic-sea-ice.net/index.php/topic,72.0.html (http://forum.arctic-sea-ice.net/index.php/topic,72.0.html)

Also from the following reference, I present the following quote citing the "ephemeral" nature of the stability of the Thwaites Glacier if circulating waters substantially reduce the basal resistance in the gateway area:

Dynamic (in)stability of Thwaites Glacier, West Antarctica,
by B. R. Parizek, K. Christianson, S. Anandakrishnan, R. B. Alley, R. T. Walker, R. A. Edwards, D. S. Wolfe, G. T. Bertini, S. K. Rinehart, R. A. Bindschadler, S. M. J. Nowicki, Article first published online: 16 MAY 2013, DOI: 10.1002/jgrf.20044;  Journal of Geophysical Research

"In addition to the SeaRISE data sets, we use detailed aerogeophysical and satellite data from Thwaites Glacier as input to a coupled ice stream/ice-shelf/ocean-plume model that includes oceanic influences across a several kilometers wide grounding zone suggested by new, high-resolution data. Our results indicate that the ice tongue provides limited stability, and that while future atmospheric warming will likely add mass to the surface of the glacier, strong ice stream stabilization on bedrock highs narrower than the length of the grounding zone may be ephemeral if circulating waters substantially reduce basal resistance and enhance melting beneath grounded ice within this zone."
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 04, 2013, 12:27:33 PM
Jim and ASLR,

Thanks for the great contributions. I think the overview on RealClimate by Rahmstorf is very useful and to the point. In the comments there someone posted this video of a lecture by Richard Alley:
Slip Slidin' Away - Ice sheets and sea level in a warming world (http://www.youtube.com/watch?v=o4oMsfa_30Q#ws)

The last four minutes of this lecture I find particulary interesting, where Alley says we can't rule out an abrupt SLR by a collapse of the WAIS of maybe up to 3m in about a century. This may not happen at all, or not for centuries, but we unfortunately cannot be sure that such a collapse will not start within this century.

Also Rahmstorf adds in the comment section (inline response to comment #19):
"Semi-empirical models have been criticised for potentially underestimating non-linear ice-sheet responses, like what Richard Alley talks about in his lecture. I think there are some arguments why these models might underestimate and some why they might overestimate future sea-level rise, but ultimately we do not know."

So, in addition to earlier comments here and to ASLR's pointer to the very interesting workshop next week, I think Alley and Rahmstorf give reasonable arguments for taking Pfeffer's risk of about 2m of SLR by 2100, or maybe even some more, seriously into account at this point in the scientific discussion.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 04, 2013, 12:57:53 PM
This paper by Rahmstorf and colleagues, Schaeffer et al (2012), I find also very interesting:
http://www.climateanalytics.org/sites/default/files/attachments/publications/Schaeffer%20et%20al%20%282012%29%20Long-term%20SLR.pdf (http://www.climateanalytics.org/sites/default/files/attachments/publications/Schaeffer%20et%20al%20%282012%29%20Long-term%20SLR.pdf)

From their table 1 it seems possible to conclude that even in their CPH reference scenario, which is not a worst-case yet, a risk of about 1.4m of SLR in 2100 and about 4m by 2200 seems possible. So it seems likely that their worst-case scenario will look about the same as that of Meehl et al, mentioned above. And just as in Meehl et al, Schaeffer et al show a risk of about 1m of SLR even in scenarios that have a more than 50% chance of staying below 2 degrees C of warming.
Title: Re: Sea Level Rise Projections and Maps
Post by: AbruptSLR on September 04, 2013, 01:17:02 PM
Lempert et al. 2012 provide the Beta PDF for Pfeffer et al 2008's SLR projections, shown in the attached image; which also provides a rough comparison with both the low and high SLR ranges for Pfefer et al 2008 and for Rohling et al 2007 and also the average low (0.6m) and the average high (1.25m) SLR for projections selected by NOAA for SLR by 2100.  Examining this figure one sees that not only is the Rohling et al high range higher than that for Pfeffer et al; but the Beta PDF from Pfeffer et al's work shows a good probability of exceeding Pfeffer et al's "limit" of 2m SLR by 2100.

Furthermore since 2008, SLR has only followed the high range and radiative forcing has exceeded the RCP 8.5 98%CL scenario; thus if one were to redraw today a PDF from Pfeffer et al 2008's work one would need to trim off some of the lower (left-hand) tail area associated with the low SLR range projections, and add to the upper (right-hand) trail area associated with the upper SLR range projections.  Indeed, the longer society follows the BAU path the more the SLR PDF for 2100 will shift to high values.

Also, in this post, I would like to note that since before 2000 the Earth has been in an El Nino hiatus period; and when this oscillation (the PDO) swings out of this hiatus period, SLR can be expected to accelerate beyond the values that we (and Pfeffer) have been observing recently.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 04, 2013, 01:39:44 PM
Ah, so Pfeffer's position does not even differ so much from Hansen's after all :)

Another point made by Hansen, the possibility of 'scientific reticence' and/or a 'Millikan Effect', or maybe also a scientific inclination to 'err on the side of least drama' (Rysse et al 2012) rather than being accused of/for 'crying wolf':
http://www.columbia.edu/~jeh1/mailings/2012/20121226_GreenlandIceSheetUpdate.pdf (http://www.columbia.edu/~jeh1/mailings/2012/20121226_GreenlandIceSheetUpdate.pdf)

Hansen even resorts to literary tactics in trying to make his point:
http://www.giss.nasa.gov/research/briefs/hansen_12/ (http://www.giss.nasa.gov/research/briefs/hansen_12/)

And Rysse et al 2012:
http://www.wageningenur.nl/upload/24618685-3919-475e-a59c-823e90376072_erring.pdf (http://www.wageningenur.nl/upload/24618685-3919-475e-a59c-823e90376072_erring.pdf)

Maybe there could also be an effect that scientists, being human, can sometimes be frightened by possible conclusions from their work?
Title: Re: Sea Level Rise Projections and Maps
Post by: AbruptSLR on September 04, 2013, 04:13:41 PM
Lennart,

All that I can say is that when a multinational oil/gas company wants to drill in deep offshore water (such as BP in the Gulf of Mexico), they are required to conduct, and submit for review, a detailed hazard analysis of worst case scenarios.  However, when modern society wants to conduct a one of a kind experiment on the Earth's climatic system, that could result in billions of deaths in the next hundred years or so, there is no requirement to perform a hazard analysis, or to take precautions; all that most people think that they need to do is to look around and to see if they are doing as well as their neighbors; and if so, most people think that things are as they should be.

Best,
ASLR
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 04, 2013, 05:44:10 PM
Lennart

I am finished working through the RealClimatre posts by Ramsdorf and the comments and I either did not find an answer to your question or I did not understand it when it went by.  The following comment to the post is the closest I found to anything providing a clue.

Quote
...Some good news: Not much additional response in SLR until 650 ppm. “sea level stays more or less constant for CO2 changes between 400 and 650 parts per million and it is only for CO2 levels above 650 parts per million that the researchers again saw a strong sea level response for a given CO2 change.”

This indicates the relative stability of the East Antarctic Ice Sheet. However, I don’t think we should take this as an excuse for burning fossil fuels up to 650 ppm, as the additional forcing will probably cause a faster rate of sea level rise.

where the poster was talking about paleo records which indicate that slr is not linear with rising CO2 but, for some reason, stalls out for a time between 400-650 and then takes off again.  This is very strange to me and I wonder if you or ASLR know what could cause such a result.  It seems to defy physics.  I am wondering if they made a mistake. 

But the post brought up the question in my mind that if the paleo records (which are not perfect and have their own issues, but are still real data) show a non-continuous rise in slr (speeds up , slows down, speeds back up) due to rising CO2 levels and the various forms of modeling assume a more linear steady state rise then perhaps this difference would also result in different answers.  Do you think that could be part of the answer?

Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 04, 2013, 06:10:39 PM
ASLR, agreed on the need for hazard analysis.

Jim, that's based on Foster & Rohling, I think. It is indeed intriguing.

There could be some 'hysteresis' in the response of EAIS, as Jim Hansen agrees, but he questions if it is as strong as Foster & Rohling seem to find. However, the hysteresis that F&R find, still seems to be significantly smaller than the hysteresis observed in traditional ice sheet models.

One difference between Hansen and F&R seems to be that Hansen thinks CO2-levels between 60 and 10 million years ago were lower than F&R assume. This seems to be a real open question in paleo studies.

As mentioned before, there are reasons to think that at least part of EAIS will respond earlier and stronger to global warming than previously thought. So, this potential or probable hysteresis may delay SLR from say 20-35m, but our problems with SLR (not to mention other effects of warming which may be even more urgent) will start long before we've reached 20m, and that may already be (largely) locked in, although we may still be able to strongly slow the rate of the rise and limit it to maybe 10-15m in the long run, if we're lucky.

Other than that, I'm just a lay-man and not nearly enough of an expert to really understand the potential causes for this apparently plausible (to scientists) hysteresis-property of EAIS.
Title: Re: Sea Level Rise Projections and Maps
Post by: AbruptSLR on September 05, 2013, 12:12:24 AM
In reponse to Jim's question, I do not know the answer but I offer the following points:

(1) Paleo data is generally in climatic equalibrium which means that at a CO2 concentration of 400ppm, the corresponding sea level in the past could be 8 to 12m higher than today (as we are far from equalibrium now).  This implies that in the past at 400ppm all of the unstable parts of the WAIS, the EAIS and the GIS (and Mountain Glaciers) could have melted; leaving only the stable parts of the EAIS and of the GIS to contribute further SLR; which might take more forcing.

(2) We need to remember that the continents were in different configurations in the distant past, so the Earth System Sensitivity was different in the past than today, so we cannot directly compare the impact of past CO2 concentrations on todays conditions.

(3) It is possible that to melt stable parts of the EAIS and the GIS might require an equable climate condition; which might require a certain threshold level of CO2 to engage.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 05, 2013, 02:18:39 PM
Thanks to this good find by Artful Dodger we can now read the full paper by Meehl et al (2012), Relative outcomes of climate change mitigation related to global temperature versus sea-level rise:
http://robinlea.com/pub/nclimate/nclimate1529.html (http://robinlea.com/pub/nclimate/nclimate1529.html)

Supplementary info here:
http://www.nature.com/nclimate/journal/v2/n8/extref/nclimate1529-s1.pdf (http://www.nature.com/nclimate/journal/v2/n8/extref/nclimate1529-s1.pdf)
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 05, 2013, 02:43:50 PM
ASLR,

The differing past configurations of the continents indeed make it more difficult to determine and compare earth system sensitivities then and now. It still seems an open question however, how big the impact of continental drift etc on these sensitivities has been. I think arguments have been made (again by Jim Hansen, among others) that CO2 is by far the most dominant influence on climate on the time scales of millions of years.

So we can't be sure, but maybe the influence of continental drift in the sense you mention has been limited. It's influence on CO2 in the atmosphere may be more important by speeding up or slowing down vulcanism and weathering processes (thru uplift or subsidence of mountain ranges for example).

If you know scientists/papers which strongly argue differently, I would be interested to learn more.

Foster & Rohling conclude that 400 ppm seems correlated to past sea levels about 24m (-15/+7m) higher than today, with an 84% chance that at this CO2-level it will rise at least 9m in the long run. So a SLR somewhere between 10-30m seems quite possible, although the higher values may be less likely than the lower ones, if I understand correctly.

Their findings have probably not (yet?) been checked for glacial isostatic adjustment, so maybe that could also change them somewhat? I will see if I can find out more on that.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 05, 2013, 03:26:51 PM
Some more relevant quotes from Foster & Rohling:

"The compiled CO2 and sea-level records cover about two thirds of the last 40 My, but not in a continuous fashion (Fig. 2), and we restrict our selection to the time periods with the highest density of data for both sea-level and CO2. Although other variables and boundary conditions that influence ice growth/retreat also may have changed between the time intervals (e.g., ocean gateway configurations, continental positions, and orography), we focus here on establishing the first-order relationships and accept that these may be refined further by future studies."

"There is a clearly sigmoidal relationship between sea level and climate forcing by CO2. Moreover, there is a striking similarity between data from different time periods and those generated by different techniques (e.g., Fig. 3A). This overall agreement implies that this relationship is robust and reflects the fundamental behavior of the Cenozoic climate system, despite some significant changes in boundary conditions (e.g., closing of the Panama Gateway since the Pliocene, closure of Tethys since the Miocene)."

"In the Pleistocene (CO2 < 280 ppm), there is no evidence of hysteresis beyond a few thousand years; intervals with increasing and decreasing CO2 give a similar sea-level response (Fig. 1), as also was elaborated for the relationship between sea level and temperature in that period (9). Similarly, for the Miocene (CO2 < 450 ppm), there is no evidence of hysteresis within a temporal resolution of ~300,000 y (Fig. 2). Conversely, the Eocene–Oligocene data show some suggestion of hysteresis (SI CO2 and Sea-Level Estimates and Fig. S3). As yet, this remains insufficiently defined, but it concerns only times with CO2 > 800 ppm (Fig. S3)."

"This assessment (Fig. 3B) clearly reveals a sea-level “plateau” at around 22 m between CO2 levels of about 400 and 650 ppm, with average 68% confidence limits for this interval of +13/−12 m, which covers sea-level values that might be expected in the absence of GrIS and WAIS [+14 m (31)], although within the bounds of uncertainty, we cannot rule out that there was an additional component of mass reduction in the EAIS at these midlevel CO2 values (18, 32). Based on the probability maximum and full contributions from GrIS and WAIS, this may have been equivalent to about 10 m of sea-level rise."

"Our observed long-term relationship between sea level and CO2 forcing reaffirms the importance of CO2 as a main driver of changes in the Earth’s climate over the past 40 My."

"We observe a lack of long-term sea-level response for CO2 levels between about 650 and 400 ppm. This suggests that during these times, very little continental ice grew (or retreated); presumably CO2 was too high, hence the climate too warm to grow more continental ice after the “carrying capacity” of the EAIS had been reached (Fig. 3A). It also suggests that 300–400 ppm is the approximate threshold CO2 value for retreat and growth, respectively, of WAIS and GrIS (and possibly a more mobile portion of EAIS). Sea levels of 20–30 m above the present during the Pliocene and Miocene, when CO2 was largely between 400 and 280 ppm, are thought to predominantly reflect mass changes in the GrIS and WAIS (26, 31). However, recent records proximal to the Antarctic ice sheet indicate that some portion [maybe as much as 10 m sea-level equivalent (26, 34)] of the EAIS also retreated during these warm periods (26, 35)."

"Although the overall shape of our ln(CO2/C0):SL relationship is similar to that inferred using inverse modeling of the benthic foraminiferal δ18O record (39), our compilation places the transition from a nonglaciated to fully glaciated EAIS at considerably higher CO2 (650–1,000 ppm CO2 vs. their 380–480 ppm CO2; Fig. 3C)."

"Because it is constrained by real-world observations of the Earth system, our relationship inherently includes all feedbacks and processes that contribute to sea-level change. It also appears to be largely independent of other boundary condition changes and therefore may be used with confidence to determine a likely estimate for sea level if theEarth system were to reach equilibrium with modern or future CO2 forcing. Given the present-day (AD 2011) atmospheric CO2 concentration of 392 ppm, we estimate that the long-term sea level will reach +24 +7/−15 m (at 68% confidence) relative to the present. This estimate is an order of magnitude larger than current projections for the end of this century [up to 2 m; best estimate, 0.8 m (41)] and seems closer to the worst-case long-term sea-level projection portrayed by Meehl et al. (1)."
Title: Re: Sea Level Rise Projections and Maps
Post by: AbruptSLR on September 05, 2013, 03:42:52 PM
Lennart,
In response to your questions please briefly scan through replies #55 to 68 and #71 to 73, and then focus on the reference discussed in reply #74, which cites a consistent 5oC temperature difference for the same atmospheric CO₂ concentrations between modern and early Eocene conditions, per the following link:

http://forum.arctic-sea-ice.net/index.php/topic,130.50.html (http://forum.arctic-sea-ice.net/index.php/topic,130.50.html)

Also, note that per reply # 31 in the following link, during the early Eocene, the bed of the West Antarctic was above modern sea level; which implies that equable climate conditions may have been required to keep glaciers from forming in this area as well prior to 32 MYA.


http://forum.arctic-sea-ice.net/index.php/topic,314.0.html#lastPost (http://forum.arctic-sea-ice.net/index.php/topic,314.0.html#lastPost)

Best,
ASLR
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 05, 2013, 04:43:30 PM
ASLR,

Thanks for the references, that I've only scanned quickly so far. So maybe the past continental configuration is a much more important factor after all, in contrast to what Hansen and Rohling seem to think. I will need some time to study your references and see what I can understand :)

Cheers!
Lennart
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 05, 2013, 05:42:12 PM
Reading the full Meehl et al (2012) paper shows that their worst-case SLR-scenario for 2100 is about 145cm and for 2300 it's around 960 cm. See their figure 3 again, attached below.

As they say in the paper:
"These values inform the upper range of the shading in Fig. 3 that encompasses the larger estimates. But the limit of the higher end of the shading is depicted as being indistinct to reflect that these are only estimates. There is no real way of knowing if these higher total sea-level rise values are credible, or if higher or lower values are more likely."

From eye-balling the figure itself it looks as if these estimates have uncertainty ranges up to almost 2m for 2100, almost 6m for 2200 and almost 12m for 2300, of course bearing the above quote in mind.
Title: Re: Sea Level Rise Projections and Maps
Post by: AbruptSLR on September 05, 2013, 05:50:31 PM
Lennart,

While you study the references that I cited; remember that Hansen et al expect that the "slow response" feedback mechanisms (e.g.: "albedo flip", collapse of the WAIS, etc.) will occur more quickly than assumed by the references that I gave.  Therefore, I am not saying that Hansen et al are wrong, but rather that there is some climate state threshold that must be crossed before the world slips into an equable climate, where relatively low Global Mean Temperatures can result in high sea levels.

Personnally, I am concerned that when the modern climate condition is forced by between 800 to 1,000 ppm CO2 equivalent (note that I include the carbon dioxide equivalent of a significant increase of methane say from the permafrost or marine methane hydrates in these concentration values), that we might then collapse into an equable climate with one single atmospheric Hadley Cell, and a very high risk of abrupt SLR, for several centuries to come as occurred in MeltPulse 1A (no matter what the current GCM projections imply).

Best,
ASLR
Title: Re: Sea Level Rise Projections and Maps
Post by: AbruptSLR on September 06, 2013, 06:59:51 PM
In my initial response to JimD on this matter, I incorrectly stated that Pfeffer et al's 2008 initial ice mass loss values from the Amundsen Sea sector may need to be increased by 25% due to GIA corrections.  While the actual amount of the GIA correction is in dispute, if the following reference is correct, then the Pfeffer et al 2008 values may need to be increased by 40% (not 25%):


An investigation of Glacial Isostatic Adjustment over the Amundsen Sea sector, West Antarcticaby: A. Groh; H. Ewert, M. Scheinert, M. Fritsche, A. Rülke, A. Richter, R. Rosenau, R. Dietrich
http://dx.doi.org/10.1016/j.gloplacha.2012.08.001 (http://dx.doi.org/10.1016/j.gloplacha.2012.08.001)

Abstract
"The present study focuses on the Amundsen Sea sector which is the most dynamical region of the Antarctic Ice Sheet (AIS). Based on basin estimates of mass changes observed by the Gravity Recovery and Climate Experiment (GRACE) and volume changes observed by the Ice, Cloud and Land Elevation Satellite (ICESat), the mean mass change induced by Glacial Isostatic Adjustment (GIA) is derived. This mean GIA-induced mass change is found to be 34.1 ± 11.9 Gt/yr, which is significantly larger than the predictions of current GIA models. We show that the corresponding mean elevation change of 23.3 ± 7.7 mm/yr in the Amundsen Sea sector is in good agreement with the uplift rates obtained from observations at three GPS sites. Utilising ICESat observations, the observed uplift rates were corrected for elastic deformations due to present-day ice-mass changes. Based on the GRACE-derived mass change estimate and the inferred GIA correction, we inferred a present-day ice-mass loss of − 98.9 ± 13.7 Gt/yr for the Amundsen Sea sector. This is equivalent to a global eustatic sea-level rise of 0.27 ± 0.04 mm/yr. Compared to the results relying on GIA model predictions, this corresponds to an increase of the ice-mass loss or sea-level rise, respectively, of about 40%."

Note that in the Antarctic folder, the "Surge" thread and the "Tectonic" threads both have additional discussion on this matter.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on September 06, 2013, 07:59:32 PM
ASLR  thanks.  You and Lennart have helped me learn about this far more than I anticipated.

When one looks at all the papers we have been discussing above it seems as if the general consensus is that a collapse of the PIGS/Thwaites complex will not happen soon enough to impact the 2100 numbers significantly (depending on what significant means to each author).  Your last post indicates that we could add 40% to the Pheffer numbers for Antarctica but that would still leave us under 3m total slr in 2100 correct?

So I guess this leaves me with a question about how soon/fast the west Antarctic could destabilize and how fast of a rise in sea level that could result from that.  I have spent some time reading about this question and I have not come up with a suitable set of scientific papers which contain projections.   In your first post in Hazard Analysis for Pig/Thwaites you indicate that you expect them to be in collapse sometime in the 2050/60 timeframe. When you finish this analysis are you intending to make slr projections for 2100 and other times along the lines of what the authors above have done?
Title: Re: Sea Level Rise Projections and Maps
Post by: AbruptSLR on September 06, 2013, 11:06:05 PM
Jim,

The general opinion at the moment (per NOAA) is that the WAIS will not collapse this century, and that by 2100 SLR will be between 1 to 7-ft, with a most probable value of about 4-ft (1.22m); and NOAA's position is that the user of their SLR guidance needs to decide for themselves how much risk they do, or do not want to take, as it is currently not possible to predict SLR by 2100, and some researchers such as James Hansen have not back away from their earlier estimates of about 5m of SLR by 2100 (assuming the WAIS does collapse by then).

Regarding whether I am going to pull my numerous posts together into my own SLR projection, I have already done so in the "Philosphical" thread in the Antarctic folder, but I attach one version of this projection here (for the record), and all of my posts in the Antarctic folder since creating my SLR projection, are intended to provide additional support that this worst case projection is credible.  In the attached figure:

(a) SBEHA is my "Scenario Based Engineering Hazard Assessment" for use as a "Maximum Credible SLR Event" by 2100, which is intended as a worst case resiliency case for infrastructure (engineering) planning;

(b) RSLR in this figure is the relative SLR for California, while eustatic is the mean global SLR by 2100;

(c) RP&V is: Rahmstorf, S., Perrett, M., and Vermeer, M. (2011), "Testing the robustness of semi-empirical sea level projections", Clim Dyn, Springer-Verlag, doi: 10.1007/s00382-011- 1226-7

(d) the percentages give are for radiative forcing Confidence Levels of the RCP 8.5, which is taken as the worst case forcing scenario.


Editorial Note: The attached figure assumes that the atmospheric circulation will not transition to that for an equable climate before 2200.  However, I have provided some discussion in the Antarctic folder indicating that if we stay on the RCP 8.5 95% CL path that we currently are on, then Earth might transition to a stable equable climate pattern circa 2100; which would in my opinion continue the abrupt SLR trend beyond 2100 until eustatic sea level has risen by about 216-ft (66 m) sometime around 3200.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 19, 2013, 03:20:49 PM
Two quotes from the new paper by Hansen et al 2013 that are particularly noteworthy, at least to me, living in Holland:
http://m.rsta.royalsocietypublishing.org/content/371/2001/20120294.full.pdf (http://m.rsta.royalsocietypublishing.org/content/371/2001/20120294.full.pdf)

“The empirical data support a high sensitivity of the sea level to global temperature change, and they provide strong evidence against the seeming lethargy and large hysteresis effects that occur in at least some ice sheet models [p.22].”

“The amount of CO2 required to melt most of Antarctica in the MMCO [Middle Miocene Climatic Optimum, about 16 million years ago] was only approximately 450–500 ppm, conceivably only about 400 ppm. These CO2 amounts are smaller than suggested by ice sheet/climate models, providing further indication that the ice sheet models are excessively lethargic, i.e. resistant to climate change [p.23].”

So we could be very close to melting all of the ice on Earth, resulting in about 70m of SLR. Maybe that would take as little as a few millennia and could be very hard to stop, if we don't succeed in decarbonizing our economy very fast and/or in geoengineering our way out of this prospect. About 10m of SLR, including contributions from EAIS, could be possible in the coming three centuries, which may be inevitable in the longer term anyhow, but could still be slowed down substantially by fast decarbonization.

How Holland and the world could or would adapt to 10m of SLR over the coming centuries is an interesting question, but it looks like it would be a lot more expensive than rapidly decarbonizing. Which of course would also mitigate the need for adaptation to earlier and maybe even more urgent pressures, like food and water shortages, heat waves, droughts, fires, storms, floods, diseases, migration and conflicts over all kinds of resources.
Title: Re: Sea Level Rise Projections and Maps
Post by: Shared Humanity on September 19, 2013, 06:25:38 PM
"How Holland and the world could or would adapt to 10m of SLR over the coming centuries is an interesting question....."

In the most recent National Geographic, there is a nice article on the impact of sea level rise.

http://ngm.nationalgeographic.com/2013/09/rising-seas/folger-text (http://ngm.nationalgeographic.com/2013/09/rising-seas/folger-text)

The author spent quite a bit of time in Holland to get a sense of how the most skilled nation in the world is currently battling this rise. If you read the article, "a recent Dutch study predicted that the Netherlands could engineer solutions at a manageable cost to a rise of as much as five meters, or 16 feet."

Keep in mind this is a wealthy country with a great deal of expertise in dealing with the sea. Most other nations will not be able to deal with such a rise and, for some areas such as Florida, there are simply no solutions that will prevent the complete evacuation of the southern 1/3 of the state, including Miami. In fact most of South Florida will lose its source of drinking water with a sea level rise of 2 feet as sea water poisons all current sources of fresh water.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 19, 2013, 10:11:17 PM
Very nice article indeed. I'll have to find out which recent report said about 5m of SLR would still be manageable for the Netherlands. Sounds like the number I've heard before, but have never really seen the underlying reasoning for.

We had a new Delta Committee a few years ago, who assumed the worst-case would be a little over 1m of SLR by 2100 and about 3.5m by 2200. That seem like underestimates for worst-cases by now.

I live and work in The Hague myself. For planning the municipality uses 60cm by 2100 and 120cm by 2200 as SLR-scenarios. Way too low in my opinion, but so far I see little willingness to consider higher scenarios, like the NOAA worst-case scenario of 2m by 2100.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on September 20, 2013, 03:43:31 PM
The following two papers give further support to the apparent vulnerability of the EAIS at current CO2-levels and the high probability of at least 17m of SLR in the long term if we don't manage to reduce these levels.

Dwyer & Chandler 2009, Phil. Trans. R. Soc.;
Mid-Pliocene sea level and continental ice volume based on coupled benthic Mg/Ca palaeotemperatures and oxygen isotopes:
http://rsta.royalsocietypublishing.org/content/367/1886/157.full.pdf+html (http://rsta.royalsocietypublishing.org/content/367/1886/157.full.pdf+html)

ABSTRACT:
"Ostracode magnesium/calcium (Mg/Ca)-based bottom-water temperatures were combined with benthic foraminiferal oxygen isotopes in order to quantify the oxygen isotopic composition of seawater, and estimate continental ice volume and sea-level variability during the Mid-Pliocene warm period, ca 3.3–3.0 Ma. Results indicate that, following a low stand of approximately 65 m below present at marine isotope stage (MIS) M2 (ca 3.3 Ma), sea level generally fluctuated by 20–30 m above and below a mean value similar to presentday sea level. In addition to the low-stand event atMIS M2, significant low stands occurred at MIS KM2 (K40 m), G22 (K40 m) and G16 (K60 m). Six high stands ofC10 m or more above present day were also observed; four events (C10, C25,C15 and C30 m) from MIS M1 to KM3, a high stand of C15 m at MIS K1, and a high stand of C25 m at MIS G17. These results indicate that continental ice volume varied significantly during the Mid-Pliocene warm period and that at times there were considerable reductions of Antarctic ice."

Kenneth G. Miller, James D. Wright, James V. Browning, Andrew Kulpecz, Michelle Kominz, Tim R. Naish, Benjamin S. Cramer, Yair Rosenthal, W. Richard Peltier and Sindia Sosdian 2012, Geology;
High tide of the warm Pliocene: Implications of global sea level for Antarctic deglaciation:
http://geology.rutgers.edu/images/Publications_PDFS/Miller_2012.pdf (http://geology.rutgers.edu/images/Publications_PDFS/Miller_2012.pdf)

ABSTRACT:
"We obtained global sea-level (eustatic) estimates with a peak of ∼22 m higher than present for the Pliocene interval 2.7–3.2 Ma from backstripping in Virginia (United States), New Zealand, and Enewetak Atoll (north Pacific Ocean), benthic foraminiferal δ18O values, and Mg/Ca-δ18O estimates. Statistical analysis indicates that it is likely (68% confidence interval) that peak sea level was 22 ± 5 m higher than modern, and extremely likely (95%) that it was 22 ± 10 m higher than modern. Benthic foraminiferal δ18O values appear to require that the peak was <20–21 m. Our estimates imply loss of the equivalent of the Greenland and West Antarctic ice sheets, and some volume loss from the East Antarctic Ice Sheet, and address the long-standing controversy concerning the Pliocene stability of the East Antarctic Ice Sheet."

So this last study indicates there seems to be about 84% chance that sea level will rise at least 17m in the long term, if current CO2 levels are not reduced over the coming centuries.
Title: Coastal erosion
Post by: Anne on October 05, 2013, 04:19:55 PM
Coastal erosion is happening unexpectedly fast (http://barentsobserver.com/en/nature/2013/10/arctic-coastlines-threatened-melting-permafrost-05-10) as the buffer zone of sea ice and permafrost declines. This threatens not only habitations but also onshore gas and oil infrastructure.

Quote
ABSTRACT
Permafrost coasts make up to 34 per cent of the world's coastlines. Erosion of these coasts currently averages 0.5 m a-1, which is similar to or greater than rates observed in temperate regions. The erosion rate has risen on the Arctic coast of Alaska during the first decade of the 21st century as the minimum sea ice extent has declined. Increasing erosion leads to higher engineering and relocation costs for coastal villages (US$140 million for Kivalina alone to adapt and eventually relocate), and to greater quantities of organic carbon contained in permafrost being released to the near-shore zone (up to 46.5 Tg a-1). Modelling of coastal erosion has begun to include permafrost-specific components such as block failure. The absence of basic information on Arctic coasts that would be provided by a dedicated observing network, especially on lithified coasts, has hindered the development of a system model with predictive capability.

Recent Progress Regarding Permafrost Coasts (http://onlinelibrary.wiley.com/doi/10.1002/ppp.1777/full)
H. Lantuit*, P. P. Overduin, S. Wetterich
Title: Re: Sea Level Rise Projections and Maps
Post by: LRC1962 on October 07, 2013, 06:57:48 AM
Came across this page: http://ngm.nationalgeographic.com/2013/09/rising-seas/uneven-impacts-map (http://ngm.nationalgeographic.com/2013/09/rising-seas/uneven-impacts-map)
Granted NG is not a scientific pear review publication but they do generally do good reporting.
http://ngm.nationalgeographic.com/2013/09/rising-seas/uneven-impacts-map (http://ngm.nationalgeographic.com/2013/09/rising-seas/uneven-impacts-map) shows impacts based on 4ft rise by 2100. The scary part is that there are those on the ground reporting from both Greenland and Antarctica that are saying it could easily be by 2050. Not only that, every time a new study gets completed from these ice sheets they seem to come to the same conclusion: Its worse then we thought it would be.
Title: Re: Sea Level Rise Projections and Maps
Post by: wili on December 04, 2013, 07:18:46 PM
http://www.jamstec.go.jp/jamstec-e/iugg/htm/abstract/abst/jsm04/018042-2.html (http://www.jamstec.go.jp/jamstec-e/iugg/htm/abstract/abst/jsm04/018042-2.html)


Experts say the IPCC underestimated future sea level rise


Quote
It looks like past IPCC predictions of sea level rise were too conservative; things are worse than we thought.

(Somehow I feel like I've heard that last phrase before, someplace...)

Quote
That is the takeaway message from a new study out in Quaternary Science Reviews and from updates to the IPCC report itself. The new study, which is also discussed in depth on RealClimate, tries to determine what our sea levels will be in the future. What they found isn't pretty...

the authors took a different approach. They decided to ask the scientists themselves. What do they think sea level rise will be by 2100 and 2300 under different greenhouse gas scenarios? The authors found 360 sea-level experts through a literature survey. They then worked to find contact information for these scientists and finally, they sent a questionnaire. After receiving 90 expert judgments from 18 countries, the results were tallied. So, what do experts think?


...According to the more likely higher emission scenario, the results are 0.7–1.2 meters (2.3–3.9 feet) by 2100 and 2.0–3.0 meters (6.5–9.8 feet) by 2300. These are significantly larger than the predictions set forth in the recently published IPCC AR5 report. They reflect what my colleagues, particularly scientists at NOAA, have been telling me for about three years.

Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on December 04, 2013, 08:45:49 PM
Wili

These numbers from that survey are right in line with our discussions in this thread.  While the IPCC numbers are conservative as would be expected given the process they work under, the numbers put forth in the studies we identified and from statements by recognized experts fell pretty much exactly where this survey landed.  So there is no surprise here is there?
Title: Re: Sea Level Rise Projections and Maps
Post by: ritter on December 04, 2013, 11:13:59 PM
The State of California is estimating a 1.0 to 1.4 meter sea level rise by 2100.

edited to add: Wrong link, Wili.
Title: Re: Sea Level Rise Projections and Maps
Post by: wili on December 05, 2013, 12:13:41 AM
Ooops, sorry. http://www.theguardian.com/environment/climate-consensus-97-per-cent/2013/dec/04/experts-ipcc-underestimated-sea-level-rise (http://www.theguardian.com/environment/climate-consensus-97-per-cent/2013/dec/04/experts-ipcc-underestimated-sea-level-rise)

Yeah, I think this is just new reporting on a report that we've already discussed.

Sorry. Not feeling great today. Posting while sick apparently can lead to as many gaffs as posting drunk (don't both, I must confess).

Best to all,
Dohboi
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on December 05, 2013, 10:58:03 AM
John Abraham writes in the Guardian and on Skeptical Science:

"According to the best case scenario (humans take very aggressive action to reduce greenhouse gases), the experts think sea level rise will likely be about 0.4–0.6 meters (1.3–2.0 feet) by 2100 and 0.6–1.0 meters (2.0–3.3 feet) by 2300. According to the more likely higher emission scenario, the results are 0.7–1.2 meters (2.3–3.9 feet) by 2100 and 2.0–3.0 meters (6.5–9.8 feet) by 2300."

This is what these experts as a group think likely. But what do they think is possible? What could be the worst case?

According to one of the authors, Stefan Rahmstorf, about half of these experts think there's a 5% chance that SLR by 2300 could be more than 4 meters in a worst-case scenario (whereas 3.8 meters seems to be about the worst-case according to IPCC AR5, chapter 13, figure 13.13).

Four of this half think there's a 5% chance it could be more than 9 meters. Three of these four think it could be more than 10 meters. Two of these three think it could be more than 12 meters. And one of these two thinks it could be even more than 15 meters by 2300 (see Rahmstorf's inline response to my comment 9 at the RealClimate post).

So should citizens and policy makers make decisions based on the likely range, or on the worst-case in the possible range?
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on December 05, 2013, 05:03:43 PM
Quote
...
So should citizens and policy makers make decisions based on the likely range, or on the worst-case in the possible range?

This is a difficult question and one we all wrestle with all the time here on the forum.  It certainly generates some of the more pointed discussions.

In a perfect world we could perform a rigorous risk analysis and agree to take action based upon what the numbers (so to speak) say.  We all know that is not going to happen for a variety of reasons.  Politics, money to be made, and the frailty of human nature among them.  But one absolutely critical key in making such a risk analysis is that an agreed set of experts would have to evaluate the outliers to make a determination that their estimates were sound enough to be considered in the analysis.  I don't mean to impugn the scientists who made the high estimates here, but any time you have big outliers there is the possibility of some kind of error or that a bias has crept into the analysis.  Keep the AMEG in mind when thinking about this type of issue.   

But we at the working level are already past the above issue from a practical standpoint.  Sea rise level rise is going to be catastrophic even if it is 'only' 1.5m in 2100 and 3 m by 2300.  To me at least, it gets down to arguing, in a policy sense, about how many devils one can fit on the head of a pin.  The devils have already arrived so prevention is not the issue nor is how many actually fit.

Perhaps a better strategy at this point would be to accept the median estimate and 'fully accept' its implications and propose actions based upon those numbers and what they mean.  For example at 1.5 m sea level rise Bangladesh will functionally cease to exist.  So it is time for activists to initiate the process of proposing the migration and relocation of the bulk of the population to India and Burma.  Convene a formal conference between the three countries under the sponsorship of the UN to determine where these people will live and how much they will pay the Indians and Burmese for the right to resettle in their territory.  Do not wait for the Indians to agree to show up.  Just start and they will react you can be sure.  At the same time the Dutch and other locals in northern Europe initiate the process for determining how to resettle the residents of those areas which will no longer be viable post 2100.  Organize it and start paying for it now.  The same for the  various low island countries of the Indian and Pacific Oceans.  None of the receiving locals are going to want to have anything to do with this process now or in the future.  Do not give them a choice.  Start without them.  Invite them to provide input at all stages but make it clear this is going to happen and the sooner everyone gets involved the better it will work out.

Preempt the certain to happen delaying political process by saying this is going to happen and we are starting planning now.  India has to absorb Bangladesh.  Sorry guys but that is just the way it is so deal with it starting now.  Other Europeans are going to have to accept their lowland neighbors, etc.  Drop any pretense of discussion on possibilities and just say they are coming so let us manage the process starting now.  This would, of course, cause a huge hew and cry and result in all sorts of threats and demands. But it would start the process of getting results.  As long as we put the argument among the scientists on what the eventual sea level rise is going to be on the front burner we will make no progress on actual actions.  Not that the argument has no meaning, but that the argument is well enough settled at this point that we leave the devils on the pin discussion to the experts and the rest of us get to work with planning for the inevitable.

There should be a organization in the US which guides the discussion of when we stop public infrastructure investment in low lying areas of Florida (especially Miami), Louisiana, New York/New Jersey and so on.  NO more public money goes to upgrading utilities, roads, bridges, ports, you name it.  Plan for when maintenance will cease and for when utilities will be turned off in specific areas.  When do we abandon.   No federal insurance or insurance guarantees, no disaster money for storm or sea level rise damage. You want to stay there you pay for it all out of your own pocket.  The insurance companies are eventually going to be all over this type of issue in the wealthy countries and when that happens the business interests are going to try and use their political influence to arrange for the taxpayers to provide backup for their private investments (just like the banking/investment fiasco we are stuck with).  We the citizens have to preempt such actions and the way to do it is to force the issue.

How's that for my first cup of coffee  ;D

 

Title: Re: Sea Level Rise Projections and Maps
Post by: ccgwebmaster on December 05, 2013, 05:24:30 PM
How's that for my first cup of coffee  ;D

You seem to get much better caffeine mileage than I do. What's the secret?
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on December 05, 2013, 05:40:10 PM
I was taught to make coffee by an old cowboy.  He drank 12 cups a day.  I am a wimp in comparison.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on December 05, 2013, 06:07:09 PM
Jim,
In Holland planners now assume a worst-case of 60 cm in 2100 and 120 cm in 2200, based on IPCC 2007. They know it could be worse, but at this point we don't insure ourselves against that risk. The Dutch Delta Committee considers 130 cm by 2100 and 4 m by 2200 as the worst-case (including subsidence). They think we could adapt to such rises.

Our Environmental Assessment Agency and Delft University think we can adapt to 1.5 meter/century for at least four centuries. They consider this as a worst-case, even though the main adviser to the Delta Committee say there's a significant risk of more than 1.5 meter/century. The risks for Bangladesh and other countries are not being seriously considered. It seems this is the case in other rich countries as well.

So to me it seems relevant, for both the Dutch situation and the world, if several experts think the risks are higher than IPCC thinks. Of course it would be nice to know who those experts are and how sound their judgement is. And we should definitely start doing all the things you suggest. But I think the scientific debate on the risks is more than discussing how many angels fit on the pin of a needle.
Title: Re: Sea Level Rise Projections and Maps
Post by: ritter on December 05, 2013, 06:34:47 PM
How's that for my first cup of coffee  ;D

Nice post, Jim. One of my issues with planning for sea level rise is which event horizon do we plan for? It's not as if we hit 1.5 meters at 2100 and then it stops. Do we really want to rebuild coastal infrastructure every 85-100 years? I don't think so. So then there is the issue, as you raise for Bangladesh, or orderly retreat. Just using the US as an example, how do we get the citizen fired up about absorbing the ocean-side population of Florida? These are just colossally huge problems.

edited to untangle my quotation....
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on December 05, 2013, 06:53:10 PM
Lennart

If the Dutch planners think that they can adapt to 1.5m per century rise they are a bold lot.  A rational consideration of the state that humanity is likely to be in circa 2100 and even more by 220 hundred indicates to me that they have their heads stuck into the dikes a bit too far.  Since a dramatically shrinking population and a collapsing global economy are highly probable by 2100 exactly how do they expect to pay for that adaptation and perform the work needed?

I do not mean to say that the scientific goal of ascertaining the likely sea level rise numbers and eventual equilibrium temperatures are not important.  But, from a practical perspective of get something done in time to make some kind of measurable difference for the survivors of this coming disaster, we have plenty enough data in hand already and the consensus projections are more than adequate to justify taking actions independent of what the governments are doing.   

As seen in Holland, politics will always minimize the danger and delay action as long as possible while the politicians wait for public consensus to reach the point that a political calculation says it is time to jump in front of the crowd and lead it where it is going.  The time for that kind of patience is long past. 
Title: Re: Sea Level Rise Projections and Maps
Post by: Laurent on December 05, 2013, 07:02:07 PM
I think nobody can project accurately the sea level at more than...let's say 20 years !
Why ? because we are on an exponential curve, because the past has never encountered such CO2 levels changes !
I have been to see a speech from michel Galliot (ONERC) he was speaking in the name of the IPCC saying that :
1) in 120 years the CO2 level would be back again to present level (if we stop emissions).
(I don't know the answer but it is obviously completely wrong, I am not certain but it would be a minima 500 years and more, certainly 5000 years (do you have data or accurate info ? IPCC?)
2 ) If Antarctica would melt completely it would be at max 30 meters
(Well a basic calculation base on 30 million km3 storage show it would be around 84 meters (Let's say around 63 as I have heard) but that does not include the thermal expansion that is 50 % of the sea level rise so 63 + 7 + 70 = 140 meters ouaouh That does not include the isostatic rebound of the Antarctica continental floor and the informations that I have show that around 70 millions years ago the sea level was 300 meters above ! What do you think ? )
3) well he was also saying that the scientist gather themselves on their free time and therefore their conclusions cannot be challenged !
4) That the end of the arctic would be for 2050 ! (Changing from 2100 6 years ago without apologize)
5) That if we reduce by 4 our emissions everything would be fine !
6) A woman told him about a study published in "National Geographic" saying the CO2 would be back in a few thousand years, but he dismissed the study straight away saying only IPCC was right ( I did just shut up but complained by mail to the organisation after that...they don't want to hear... I am not from IPCC you know)

If you have some links on the 5th IPCC report that match or not is speech, I would have something to argue with !
The max change rate was around 4 cm/year 14.000 years ago, I really think we can expect more !
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on December 05, 2013, 07:02:49 PM
Nice post, Jim. One of my issues with planning for sea level rise is which event horizon do we plan for? It's not as if we hit 1.5 meters at 2100 and then it stops. Do we really want to rebuild coastal infrastructure every 85-100 years? I don't think so. So then there is the issue, as you raise for Bangladesh, or orderly retreat. Just using the US as an example, how do we get the citizen fired up about absorbing the ocean-side population of Florida? These are just colossally huge problems.

That is exactly the idea.  Trying to precipitate an orderly retreat.  The attempt might well fail but the alternative certainly will fail.

If we wait until the Bangladeshi's start moving over the Indian border in mass the almost certain result will be genocide.  If we hit the Indians along the head with "They are coming to live with you and let's figure out how to manage that." then it will trigger all sorts of anguish and perhaps get some better result than just mass murder.  I am certain that one of their first responses will be that you Americans (and Europeans) made this problem so you take care of them.  A fair point that most Americans are unwitting of I would guess.  Best start arguing now is the way I look at it.
Title: Re: Sea Level Rise Projections and Maps
Post by: ritter on December 05, 2013, 07:40:22 PM
I am certain that one of their first responses will be that you Americans (and Europeans) made this problem so you take care of them.  A fair point that most Americans are unwitting of I would guess.  Best start arguing now is the way I look at it.

I believe there was just recently a breakdown in climate negotiations precisely because wealthy nations didn't want to compensate developing nations for past emissions. I will admit that looking at the adaptation concept from a world-wide perspective is just too mind boggling for me. I get all cross eyed just thinking about how to get meaningful action at our federal level!
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on December 05, 2013, 08:05:43 PM
Jim,
I agree there's enough reason for action even under IPCC consensus likely ranges. The powers that be, however, still are not willing to take this action. Maybe they need even more reason for concern...

As to the fate of the Bangladeshi: India has already built a fence on the border to keep them out. I don't know how effective that fence will be once they really start moving.
Title: Re: Sea Level Rise Projections and Maps
Post by: Shared Humanity on December 05, 2013, 09:47:04 PM
How's that for my first cup of coffee  ;D

Just using the US as an example, how do we get the citizen fired up about absorbing the ocean-side population of Florida? These are just colossally huge problems.

edited to untangle my quotation....

I vote we accept only the residents from Florida who have expressed concern about AGW. For the global warming deniers in Florida, we give them rowboats.
Title: Re: Sea Level Rise Projections and Maps
Post by: Shared Humanity on December 05, 2013, 09:55:08 PM
Quote
...
So should citizens and policy makers make decisions based on the likely range, or on the worst-case in the possible range?

Perhaps a better strategy at this point would be to accept the median estimate and 'fully accept' its implications and propose actions based upon those numbers and what they mean.  For example at 1.5 m sea level rise Bangladesh will functionally cease to exist.  So it is time for activists to initiate the process of proposing the migration and relocation of the bulk of the population to India and Burma.  Convene a formal conference between the three countries under the sponsorship of the UN to determine where these people will live and how much they will pay the Indians and Burmese for the right to resettle in their territory.

How's that for my first cup of coffee  ;D

And why exactly should this orderly relocation be to India and Burma? Given that the western world  is primarily responsible for global warming, shouldn't this relocation be to Europe and North America?
Title: Re: Sea Level Rise Projections and Maps
Post by: johnm33 on December 05, 2013, 11:33:45 PM
Laurent. Am I reading that graph correctly, Santa Catarina 40m - Sunda/Vietnam shelf 140m slr?
Title: Re: Sea Level Rise Projections and Maps
Post by: Laurent on December 06, 2013, 08:58:22 AM
I do not see -40m for Santa Catarina !
Yes -140m for Sunda/Vietnam shelf 21.000 thousands years ago, it is generally said that see level was -120 meters below 20.000 years ago.
You have to keep in mind that graph as many others do soften the datas ! It is certainly more bumpy than that on a short scale.
I join a graph taken from the thesis of a student named Alix lombard.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on December 06, 2013, 05:03:30 PM
And why exactly should this orderly relocation be to India and Burma? Given that the western world  is primarily responsible for global warming, shouldn't this relocation be to Europe and North America?

Oh exactly, exactly!  Thus my statement above

Quote
If we wait until the Bangladeshi's start moving over the Indian border in mass the almost certain result will be genocide.  If we hit the Indians along the head with "They are coming to live with you and let's figure out how to manage that." then it will trigger all sorts of anguish and perhaps get some better result than just mass murder.  I am certain that one of their first responses will be that you Americans (and Europeans) made this problem so you take care of them.  A fair point that most Americans are unwitting of I would guess.  Best start arguing now is the way I look at it.

I am thinking here in the global activist non-government role, not from the American preference.  Governments are so complacent and unlikely to act in a timely fashion they need to be preempted.  One of the best ways to get large numbers of people involved in the process is to start promoting a solution which will outrage a big group of people and several governments.  Just flat out promoting that India needs to plan to absorb Bangladesh should fit that bill in spades.  Start a big fight and then compromise towards an equitable solution.  But force people to get involved.  Maybe 350.org could get some traction out of starting to promote that the US needs to start making plans to absorb 30-50 million immigrants since we are insisting on destroying the climate (course some of my neighbors might shoot them too  :o ).

If we just cruise along until the problem is no longer theoretical and action has to be taken in the near-term we have the disaster I was trying to avoid.  Some form of genocide.  It will probably happen anyway but it seems worthwhile to try and trigger the orderly retreat as Ritter phrased it.

I must admit that I am not optimistic that any solution to very large mass migrations will ever be found.  But not trying to work that problem and just waiting for the consequences of when the train sails off into the chasm where the bridge used to be seems sort of ...immoral?...unethical?
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on February 06, 2014, 06:09:00 PM
Interesting article about what the UK is doing (or not doing as the case may be) about dealing with sea level rise.

http://www.newstatesman.com/politics/2014/02/protecting-farms-or-front-rooms-impossible-dilemma-climate-change-forces-upon-us (http://www.newstatesman.com/politics/2014/02/protecting-farms-or-front-rooms-impossible-dilemma-climate-change-forces-upon-us)
Title: Re: Sea Level Rise Projections and Maps
Post by: ccgwebmaster on February 06, 2014, 07:27:36 PM
Just flat out promoting that India needs to plan to absorb Bangladesh should fit that bill in spades.

Considering they're building a bloody great fence and beefing up their military - I think it fair to speculate India not only already realises this but has decided how it's going to approach it. Pretty much in the same way as the US approaches the border with Mexico.

I must admit that I am not optimistic that any solution to very large mass migrations will ever be found.  But not trying to work that problem and just waiting for the consequences of when the train sails off into the chasm where the bridge used to be seems sort of ...immoral?...unethical?

If population is too high, is it ethical to officiously strive to preserve life though? Is it ethical to try to absorb large numbers of people at the risk of those in the region they are moving into? If by trying to preserve too many people you threaten or damage the prospects for people indefinitely into the future, is that any more moral?

Now, if you were suggesting we take the more culpable people out of the nations most responsible for causing these problems, dump them in Bangladesh - and move the least culpable people from Bangladesh into those nations (often better placed) - sure - that would seem pretty morally sound to me. Good luck getting votes for that one though...
Title: Re: Sea Level Rise Projections and Maps
Post by: ccgwebmaster on February 06, 2014, 07:40:22 PM
This is in relation to flooding - not specifically that related to sea level rise, but suggesting that it isn't as big a driver of migration as heat stress (and hinting that the reason heat stress is bigger as a factor is because of related economic factors).

http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2103.html (http://www.nature.com/nclimate/journal/vaop/ncurrent/full/nclimate2103.html)
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on February 06, 2014, 08:16:57 PM
ccg

Quote
If population is too high, is it ethical to officiously strive to preserve life though? Is it ethical to try to absorb large numbers of people at the risk of those in the region they are moving into? If by trying to preserve too many people you threaten or damage the prospects for people indefinitely into the future, is that any more moral?

My intention for the activist community to force the contemplation of mass migrations is more to bring home to those who are unaware of it how untenable the current population is.  Maybe it would trigger serious discussion of population reductions.  Probably not of course.

In a strictly selfish long term survival sense no country should be allowing immigration.  All have too many people already.  A surprising fact to many, and also a source of some of the angst about immigration in the US, is that we allow more legal immigration by far than any other country in the world.  In 2006 our legal immigration was more than the entire rest of the world put together.  We just have our political favorites and various rules about how it is to be done.  A downside in terms of AGW is that all of those new people want a lifestyle just like everyone else here.  It would be smart of the rest of the world not to let anyone come here to live.     
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on February 24, 2014, 05:31:39 PM
A new interactive sea level rise map is available.  I like maps!

http://scalgo.com/live/global/?&center=5987771.0469141,58703.637714837&zoom=3&baselayer=Basic&flooding=1.0510942524528625&lrs=SRTM_4_1:dem,SRTM_4_1:SRTM_4_1_flooded_sealevels (http://scalgo.com/live/global/?&center=5987771.0469141,58703.637714837&zoom=3&baselayer=Basic&flooding=1.0510942524528625&lrs=SRTM_4_1:dem,SRTM_4_1:SRTM_4_1_flooded_sealevels)
Title: Re: Sea Level Rise Projections and Maps
Post by: tombond on March 01, 2014, 10:12:16 AM
With regard to SLR projections the most important period is the next 50 years or so and how we as communities plan adaptation measures.

Currently here in Western Australia the Government is planning to adapt to a SLR of about 1 metre by 2100.  However in reality coastal development is business as usual and risk analysis for SLR planning is confined to a few small sentences like those below.

"Response to changing climatic patterns will require vulnerability and risk assessment for infrastructure and communities.  For example, assessment of sea-level change may lead to responses that are precautionary and with a long-term view.  Over time this may lead to changes in policies and standards for buildings and urban structures at risk of inundation."

In other words it is too hard and too far away to worry about.

The reality is the IPCC AR5 SLR estimation of 1 metre by 2100 for the RCP 8.5 scenario is likely to be too conservative given the IPCC’s consensual process and a “snowballs chance in hell” of global governments/communities agreeing to any meaningful emission reductions before mid-century. 

By contrast Hansen’s 1 metre SLR by mid-century could be nearer a credible maximum estimation given the acceleration in land ice melt during this past decade.

http://www.columbia.edu/~jeh1/mailings/2012/20121226_GreenlandIceSheetUpdate.pdf (http://www.columbia.edu/~jeh1/mailings/2012/20121226_GreenlandIceSheetUpdate.pdf)

See also the IPCC AR5 report Summary for Policymakers - Cryosphere page 9

https://www.ipcc.ch/report/ar5/wg1/ (https://www.ipcc.ch/report/ar5/wg1/)

For the Cryosphere, it notes that the combined land ice melt rates for Greenland and Antarctica had increased from 60Gt/year for the 1990s decade to 360Gt/year for the 2000s decade, say a five year doubling period. 

Coastal planners would be wise to continually monitor land ice melt mass losses as a SLR prediction tool.  If this five year doubling period is maintained then Hansen’s estimation of SLR of one metre by mid century might be realised.  If the doubling period slows then coastal planners will have more time to plan adaptation measures.

Either way, all coastal planning decision making will be informed and based on real scientific observations and data with less chance of ‘surprises’.   
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on March 01, 2014, 03:36:41 PM
tombond

Something I always think is going on with the developers is what their calculations are on their Return On Investment and what the local rules are for depreciating their capital investments.  If they think that the entire lifecycle completes before they run into problems then they will go ahead and build even knowing that eventually the water destroys everything.  They will have their money and be long gone.  It will be someone else's problem.

I expect that for most building projects that means even by 2050 they have pocketed their money and are long gone.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on March 06, 2014, 11:57:12 AM
A new paper by Marzeion & Levermann estimates at most 8 meters of lowering around Greenland and Antarctica for 3 degrees C of warming and about 7 meters of mean global sea level rise, if I read figure 1 in their supplementary information correctly:
http://iopscience.iop.org/1748-9326/9/3/034001/media/erl491558suppdata.pdf (http://iopscience.iop.org/1748-9326/9/3/034001/media/erl491558suppdata.pdf)

The full article is about the threat of SLR to world cultural heritage:
http://iopscience.iop.org/1748-9326/9/3/034001/article (http://iopscience.iop.org/1748-9326/9/3/034001/article)

It seems still a quite conservative estimate, compared to the risks that Rohling et al 2013 see:
http://www.nature.com/srep/2013/131212/srep03461/pdf/srep03461.pdf (http://www.nature.com/srep/2013/131212/srep03461/pdf/srep03461.pdf)

They think at least 9 meters of global mean SLR in the long run is probably almost inevitable by now.
Title: Re: Sea Level Rise Projections and Maps
Post by: skanky on March 06, 2014, 12:37:45 PM
For those considering the impact on Western countries, here is an example of an attempt to move a small town - http://www.bbc.co.uk/news/magazine-26447507 (http://www.bbc.co.uk/news/magazine-26447507)

Now imagine doing the same in say, Miami.
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on March 06, 2014, 04:58:13 PM
Lennart

Thanks, good info.  Once again I note from the graphs showing expected slr with the various scenarios (and from other papers the equivalent regarding temperatures) that the longer we follow the various BAU approaches the harder it is going to be for those who pass through the bottleneck.  A limited number of people after the collapse can adapt to the world we are making in terms of slr and temperature rise, but the actual number is going to be very constrained if we run the table via BAU.  We desperately need an early collapse.
Title: Re: Sea Level Rise Projections and Maps
Post by: sidd on March 06, 2014, 08:30:13 PM
I was wrong in my statement that the fingerprint effect is only a few centimeters. There is a relatively simple treatment in Clark(1977, Nature, v267, pp 206 et seq.) which shows that in the immediate vicinity of WAIS, the SLR would fall by 500% of the global average. I enclose Fig 2. from Clark here, Please note that more sohisticated treatments are avilable today, see eg (Mitrovica, 2014, http://dx.doi.org/10.1016/j.quascirev.2013.12.022 (http://dx.doi.org/10.1016/j.quascirev.2013.12.022))

Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on March 18, 2014, 02:09:51 PM
Just another government policy gone awry.  Flood insurance.

Quote
Congress Just Undid The 1 Good Thing It's Done On Climate Change

Congress approved changes to the federal flood insurance program in June 2012 that lawmakers said then would fix the program's problems and make it more financially stable. The bipartisan reforms phased out subsidies for high-risk coastal properties, which onlookers concerned about climate change said was key to discouraging unsustainable coastal development. It was perhaps the only good thing on climate that Congress had done in a really long time.

Last week, Congress decided to undo it.

Quote
"Congress had a real opportunity here with Biggert-Waters to start to address some of the necessary reforms to the National Flood Insurance Program, both to deal with growing risk from sea level rise as well as development along our coasts," said Rachel Cleetus, a senior climate economist with the Union of Concerned Scientists. "But instead they've done what they seem to have perfected -- burying their heads in the sand. They're not dealing with the tough issues here."

I guess we could say they are burying their heads in the sand?

http://www.huffingtonpost.com/2014/03/17/congress-flood-insurance_n_4981226.html (http://www.huffingtonpost.com/2014/03/17/congress-flood-insurance_n_4981226.html)
Title: Re: Sea Level Rise Projections and Maps
Post by: JimD on March 18, 2014, 03:07:32 PM
More stupid people.

While the seas rise in the Outer Banks and elsewhere in NC, science treads water

Quote
There’s not much dispute these days, up and down the coast, about whether the ocean is rising. The question is: How high will it go here, and how fast?

North Carolinians must wait until 2016 for an official answer. That’s the law.

After promoters of coastal development attacked a science panel’s prediction that the sea would rise 39 inches higher in North Carolina by the end of this century, the General Assembly passed a law in 2012 to put a four-year moratorium on any state rules, plans or policies based on expected changes in the sea level. The law sets guidelines under which the Coastal Resources Commission, a development policy board for the 20 coastal counties, will formulate a new sea-level prediction to serve as the official basis for state planners and regulators.

http://www.newsobserver.com/2014/03/15/3702235/while-the-seas-rise-science-waits.html#storylink=cpy (http://www.newsobserver.com/2014/03/15/3702235/while-the-seas-rise-science-waits.html#storylink=cpy)
Title: Re: Sea Level Rise Projections and Maps
Post by: RaenorShine on April 29, 2014, 02:08:37 PM
http://www.bbc.co.uk/news/science-environment-27202192 (http://www.bbc.co.uk/news/science-environment-27202192)

Quote
Megacities contend with sinking land

Subsiding land is a bigger immediate problem for the world's coastal cities than sea level rise, say scientists.

In some parts of the globe, the ground is going down 10 times faster than the water is rising, with the causes very often being driven by human activity.
Title: Re: Sea Level Rise Projections and Maps
Post by: sidd on September 17, 2017, 05:59:17 AM
This is strange. AVISO shows sea level stall for one and a half years. I attach image.  colorado sealevel concurs within spread.

https://www.aviso.altimetry.fr/en/data/products/ocean-indicators-products/mean-sea-level.html (https://www.aviso.altimetry.fr/en/data/products/ocean-indicators-products/mean-sea-level.html)

http://sealevel.colorado.edu/ (http://sealevel.colorado.edu/)

Has it been raining on land more for the last yearish ? mebbe good for aquifers.

I can believe we have exported enuf heat into deep ocean to account for this. Or slowed land/above flotation ice melt by that much, about 5mm global SLR over the period.

sidd
Title: Re: Sea Level Rise Projections and Maps
Post by: oren on September 17, 2017, 07:49:39 AM
I think it's basically reversion to mean following the El NiNo. But There's also been heavy snows on Greenland this past year.
Title: Re: Sea Level Rise Projections and Maps
Post by: Aluminium on September 21, 2017, 12:50:48 AM
Hello, ASIF. :)

Few months ago I attempted to estimate acceleration of SLR. I took data from AVISO before February 2017. Simple polynomial approximation was used: at2+bt+c.

Results for 2017.0
Velocity = 0.393 cm/y. 1 sigma = 0.005 cm/y.
Acceleration = 0.0055 cm/y2. 1 sigma = 0.0004 cm/y2.
Title: Re: Sea Level Rise Projections and Maps
Post by: bligh8 on September 26, 2017, 05:03:00 PM
This is strange. AVISO shows sea level stall for one and a half years. I attach image.  colorado sealevel concurs within spread.



When Oceans Drop

Could La Niña or El Niño shrink the ocean?

“By looking at gravity measurements of oceans and land around the globe, the researchers could spot areas that weighed more in 2011. Boening said, “GRACE allowed us to actually track down the water to see where it went. And it turned out it was in northern South America, Southeast Asia, and Australia.” The strong La Niña had affected the oceans to an unusual extent, not by cooling the water so much as by moving the water on to land. Rainfall follows warm pools of water, and during El Niño, more rain tends to fall over the Pacific Ocean. But during La Niña, cooler oceans push that rainfall over continents.”

“The plot below shows ocean levels since 1993. The red line shows sea level rise and the blue line indicates the trend. The red circle shows the sudden dip in 2010 and 2011, and the arrow points to a map of where that missing water went: primarily to Australia and northern South America (indicated by blue arrows on the inset map). While the ocean lost water, the continents experienced a gain because of increased rainfall brought on by the 2010/2011 La Niña. By mid 2012, global mean sea level had recovered by more than the five millimeters it dropped.

 (Courtesy NASA JPL)”
https://earthdata.nasa.gov/user-resources/sensing-our-planet/when-oceans-drop


Title: Re: Sea Level Rise Projections and Maps
Post by: Rob Dekker on September 27, 2017, 08:36:09 AM
SLR was cruising a bit high over the past couple of years, so a bit of a stall was not unexpected.

(https://forum.arctic-sea-ice.net/proxy.php?request=http%3A%2F%2Fsealevel.colorado.edu%2Ffiles%2F2016_rel4%2Fsl_ns_global.png&hash=4e66600d8fa7751ec0de626a25244c17)

Overall, we are still seeing an acceleration of SLR since the 20th century :

(https://robertscribbler.files.wordpress.com/2016/03/global-mean-sea-level-change.png?w=479&h=322)
Title: Re: Sea Level Rise Projections and Maps
Post by: AbruptSLR on September 27, 2017, 11:05:33 AM
This is strange. AVISO shows sea level stall for one and a half years. I attach image.  colorado sealevel concurs within spread.

Following a very strong El Nino event it is normal for the sea level rise to either stall or fall back a little, but when one uses the Jason 2 time series from July 2008 to Feb 2017 (see attached image), one still gets a relatively high rate of sea level rise of 4.41 mm/year:
Title: Re: Sea Level Rise Projections and Maps
Post by: bligh8 on September 27, 2017, 04:18:21 PM
This is strange. AVISO shows sea level stall for one and a half years. I attach image.  colorado sealevel concurs within spread.

Following a very strong El Nino event it is normal for the sea level rise to either stall or fall back a little, but when one uses the Jason 2 time series from July 2008 to Feb 2017 (see attached image), one still gets a relatively high rate of sea level rise of 4.41 mm/year:

Although a relatively high rate the Jason 2 time series is down a bit. See attached image from July
2016

Title: Re: Sea Level Rise Projections and Maps
Post by: sidd on October 19, 2017, 07:59:32 PM
Sea level rise occurs in steps, new evidence from coral reefs in the last deglaciation:

https://www.nature.com/articles/s41467-017-00966-x

Open access (i checked ...) Read all about it.

sidd
Title: Re: Sea Level Rise Projections and Maps
Post by: AbruptSLR on October 26, 2017, 07:26:16 PM
The linked open access reference indicates that sea level rise projections using the new SSP forcing scenarios and emulating cliff failures and hydrofracturing leads to significantly higher estimates than were including in AR5:

Alexander Nauels , Joeri Rogelj, Carl-Friedrich Schleussner ,MalteMeinshausen and
MatthiasMengel (2017), "Linking sea level rise and socioeconomic indicators under the Shared Socioeconomic Pathways", Environ. Res. Lett. 12, 114002 https://doi.org/10.1088/1748-9326/aa92b6

http://iopscience.iop.org/article/10.1088/1748-9326/aa92b6

Abstract: "In order to assess future sea level rise and its societal impacts, we need to study climate change pathways combined with different scenarios of socioeconomic development. Here, we present sea level rise (SLR) projections for the Shared Socioeconomic Pathway (SSP) storylines and different year-2100 radiative forcing targets (FTs). Future SLR is estimated with a comprehensive SLR emulator that accounts for Antarctic rapid discharge from hydrofracturing and ice cliff instability. Across all baseline scenario realizations (no dedicated climate mitigation), we find 2100 median SLR relative to 1986–2005 of 89 cm (likely range: 57–130 cm) for SSP1, 105 cm (73–150 cm) for SSP2, 105 cm (75–147 cm) for SSP3, 93 cm (63–133 cm) for SSP4, and 132 cm (95–189 cm) for SSP5. The 2100 sea level responses for combined SSP-FT scenarios are dominated by the mitigation targets and yield median estimates of 52 cm (34–75 cm) for FT 2.6 Wm−2, 62 cm (40–96 cm) for FT 3.4 Wm−2, 75 cm (47–113 cm) for FT 4.5 Wm−2, and 91 cm (61–132 cm) for FT 6.0 Wm−2. Average 2081–2100 annual SLR rates are 5 mm yr−1 and 19 mm yr−1 for FT 2.6 Wm−2 and the baseline scenarios, respectively. Our model setup allows linking scenario-specific emission and socioeconomic indicators to projected SLR. We find that 2100 median SSP SLR projections could be limited to around 50 cm if 2050 cumulative CO2 emissions since pre-industrial stay below 850 GtC, with a global coal phase-out nearly completed by that time. For SSP mitigation scenarios, a 2050 carbon price of 100 US$2005 tCO2 −1 would correspond to a median 2100 SLR of around 65 cm. Our results confirm that rapid and early emission reductions are essential for limiting 2100 SLR."
Title: Re: Sea Level Rise Projections and Maps
Post by: Tor Bejnar on May 08, 2019, 04:26:56 PM
From the Arctic Methane Release (https://forum.arctic-sea-ice.net/index.php/topic,12.msg198372.html#msg198372) thread:

From some information I posted elsewhere (here (https://forum.arctic-sea-ice.net/index.php/topic,2543.msg198152.html#msg198152) and here (https://forum.arctic-sea-ice.net/index.php/topic,2543.msg198155.html#msg198155)), it appears that sea level around Greenland is lowering at roughly the same rate as sea level is rising 'globally', at least as long as the continental ice sheet melt is dominated by West Antarctica and Greenland (and not East Antarctica).  On a rough scale, when global average sea level rises 2 meters (about 2080-2100?), sea level 'near' Greenland (within 2,000 km, but diminishing with distance) will lower about 2 meters.

How much 'less pressure' would this represent?
Tor, I think this is not the case. It should be a factor of about 5 between Greenland sea level drop and global SLR. I think the explanation is that part of the global SLR is due to other glaciers worldwide, changes in hydrology, and thermal expansion.
Oren,
Can you explain further?  I think you saying 2 meters of global sea level rise will show as 10 meters of Greenland sea level drop - is this accurate?  reference?  Any comment on consequences of East Antarctica melt?  I've not read anything.

Title: Re: Sea Level Rise Projections and Maps
Post by: oren on May 08, 2019, 06:21:05 PM
It's certainly not accurate...
I've seen a couple of references that I will dig up later. IIRC, one of them said if West Antarctica melted, SLR would be 7 meters and sea level drop nearby could reach up to 90 meters. The other, posted on the forum recently, said if Greenland melted SLR would be 6 or 7 meters while sea level drop nearby would be 30-50 meters. Not sure why there is such a difference between the locations.
So a back of the envelope naive calculation says that for an SLR of 2m, 1m from GIS 1m from WAIS, should see a drop of 7m (40/6.5*1) near Greenland, and 13m (90/7*1) near West Antarctica. But because of the 1m coming fro the other location, it should be 6m and 12m respectively.
So my general factor should have been 3 for Greenland, and 6 for Antarctica. But it really depends on lots of variables.
Title: Re: Sea Level Rise Projections and Maps
Post by: oren on May 08, 2019, 06:29:16 PM
http://nautil.us/issue/33/attraction/why-our-intuition-about-sea_level-rise-is-wrong (http://nautil.us/issue/33/attraction/why-our-intuition-about-sea_level-rise-is-wrong)
Quote
So if the Greenland ice sheet were to catastrophically collapse tomorrow, the sea level in Iceland, Newfoundland, Sweden, Norway—all within this 2,000 kilometer radius of the Greenland ice sheet—would fall. It might have a 30 to 50 meter drop at the shore of Greenland. But the farther you get away from Greenland, the greater the price you pay. If the Greenland ice sheet melts, sea level in most of the Southern Hemisphere will increase about 30 percent more than the global average. So this is no small effect.
Title: Re: Sea Level Rise Projections and Maps
Post by: oren on May 08, 2019, 06:35:30 PM
https://news.harvard.edu/gazette/story/2010/12/ice-sheet-in-peril-gravity-to-rescue/ (https://news.harvard.edu/gazette/story/2010/12/ice-sheet-in-peril-gravity-to-rescue/)
Quote
But physics teaches that a gravitational pull is exerted by every bit of matter on every other bit of matter. Other than the grounding effect of Earth’s gravity, though, that is negligible for most aspects of our day-to-day lives. But graduate student Natalya Gomez and her adviser, Professor of Geophysics Jerry Mitrovica, have been working hard in recent years to understand the gravitational effects of the enormous areas that make up the ice sheets.

Gomez’s research makes use of the fact that the sheets are so vast that they are exerting a significant gravitational pull on the ocean. When the ice sheets melt, the expected sea level rise from all that meltwater entering the oceans would be counterbalanced by the relaxation of the sea level near the ice sheet due to a decreased pull from the gravity of the remaining ice.

The effect would be not just noticeable, but massive. In that earlier work, Gomez showed that if all of the West Antarctic sheet melted, it could actually lower sea level near the ice by as much as 300 feet.
Title: Re: Sea Level Rise Projections and Maps
Post by: Rich on May 08, 2019, 06:44:14 PM
It's certainly not accurate...
I've seen a couple of references that I will dig up later. IIRC, one of them said if West Antarctica melted, SLR would be 7 meters and sea level drop nearby could reach up to 90 meters. The other, posted on the forum recently, said if Greenland melted SLR would be 6 or 7 meters while sea level drop nearby would be 30-50 meters. Not sure why there is such a difference between the locations.
So a back of the envelope naive calculation says that for an SLR of 2m, 1m from GIS 1m from WAIS, should see a drop of 7m (40/6.5*1) near Greenland, and 13m (90/7*1) near West Antarctica. But because of the 1m coming fro the other location, it should be 6m and 12m respectively.
So my general factor should have been 3 for Greenland, and 6 for Antarctica. But it really depends on lots of variables.

It seems like the difference between WA and Greenland would be due to the distribution of gravitational forces in the region. The proportion of land mass in the South Pole tied up in ice is greater than the proportion in the region around Greenland which has a lot more land in the vicinity (Canada for example).

I would not assume that is either a linear process or that it depends on a lot of variables. The effect should be back-weighted and dependent on a single variable....gravitational force and remaining land mass.
Title: Re: Sea Level Rise Projections and Maps
Post by: gerontocrat on May 08, 2019, 07:16:52 PM
Two questions.

A general increase in sea level from the melting of the ice sheets of Greenland and Antarctica causes a localised sea level drop due to reduced gravitational pull from the reduced mass of Greenland and Antarctica. That must result in a sea level rise above the average elsewhere.
How does one calculate that? How significant is that rise above the average ?

Various examples re quoted on local sea level drop arising from various events, e.g. if Greenland melted SLR would be 6 or 7 meters while sea level drop nearby would be 30-50 meters. Can one then say if Greenland melt causes a sea level rise of 6-7 cms local sea level drop would be 30-50 cms, and would the increase elsewhere also be linear? i.e. is the relationship linear? (My guess is no - gravitational pull is proportional to the square of the distance ?)

In other words, I want to know how much extra SLR Mar-el-Largo will get if / when Greenland melts.

Title: Re: Sea Level Rise Projections and Maps
Post by: oren on May 08, 2019, 07:48:11 PM
The links I quoted said far-off places, like Miami, would see a 25% or 35% higher local SLR compared to global average SLR.

Are the processes linear? I would say yes at first approximation. Assume all mass is lost at the center of mass of the ice sheet, and the more is lost the more the local water level drops. The distances don't change, only the relative masses, hence linear. But it also depends on other SLR contributions, on the relative contribution of Greenland and the WAIS, on the local distribution of ice mass loss within the ice sheets, and on the speed of the process, as there are other processes such as isostatic uplift, and even slowdown of the planet's rotation due to more weight at the equator, thereby affecting SLR further. Without a full simulation it's impossible to account for everything. I am sure some of the papers by Mitrovica and Gomez have more detailed answers.

Re East Antarctica, I think the main assumption is that ice mass losses there will be negligible compared to the GIS and the WAIS. And I sure do hope this assumption holds.
Title: Re: Sea Level Rise Projections and Maps
Post by: Rich on May 08, 2019, 09:06:34 PM
If the gravitational mass is lost in a linear process, the gravitational force is lost is a exponentially accelerating manner.

If we assume an object weighs 100 lbs, the first 10 pounds of loss represent a 10% decrease. (10 / 100). The next 10 pounds represent an 11.1% decrease (10 / 90). The last 10 pounds represent a 100% decrease (10/10).

This is of course a simplification. Not all of the gravitational land mass in Antarctica and Greenland and Antarctica is ice. There is solid earth underneath which will continue to exert gravitational pull on the surrounding waters even after all the ice would be gone.

In the case of Greenland, there are clearly more concentrated and substantial land masses in the Arctic region such as North America and Russia which would still be pulling water toward the north pole in the absence of Greenland Ice.

Antarctica doesn't have the same concentration of land masses in the region, so Antarctic Ice represents a greater proportion of the gravitational mass in that region than Greenland does in it's own region. That's why Antarctic Ice loss would be accompanied by a larger local drop in sea level.
Title: Re: Sea Level Rise Projections and Maps
Post by: Tor Bejnar on May 08, 2019, 09:33:30 PM
The links in one of my posts (https://forum.arctic-sea-ice.net/index.php/topic,2543.msg198155.html#msg198155) had some information...
 
Quote
We lack robust forecasting models for future ice changes, which
diminishes our ability to use these fingerprints to accurately predict local sea-level (LSL)


Should coastal planners have concern over where land ice is melting?
Eric Larour,Erik R. Ivins and Surendra Adhikari
Science Advances  15 Nov 2017

Going to the abstract
 (https://advances.sciencemag.org/content/3/11/e1700537.abstract)
Quote
We apply GFM to 293 major port cities to allow coastal planners to readily calculate LSL change as more reliable predictions of cryospheric mass changes become available.
The paper is available, but I don't have time to look at it now... (get there from the abstract link)
Title: Re: Sea Level Rise Projections and Maps
Post by: Tom_Mazanec on June 04, 2019, 05:49:25 PM
Maine law is taking SLR projections seriously:
https://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=12237332
Title: Re: Sea Level Rise Projections and Maps
Post by: Shared Humanity on June 04, 2019, 06:39:00 PM
Maine law is taking SLR projections seriously:
https://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=12237332

You say "Maine law is taking SLR projections seriously:"

And then link to an article that has this title.

"Climate change doomsday report predicts end of human civilisation"

Was the link a mistake?
Title: Re: Sea Level Rise Projections and Maps
Post by: Tom_Mazanec on June 04, 2019, 06:47:03 PM
Maine law is taking SLR projections seriously:
https://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=12237332

You say "Maine law is taking SLR projections seriously:"

And then link to an article that has this title.

"Climate change doomsday report predicts end of human civilisation"

Was the link a mistake?


DA-...rhymes with ham.
Here is the correct link:
https://www.usnews.com/news/best-states/maine/articles/2019-06-04/maine-law-puts-new-focus-on-potential-toll-of-sea-level-rise

Thanks, SH. Sorry for the goof.
Title: Re: Sea Level Rise Projections and Maps
Post by: Shared Humanity on June 04, 2019, 06:50:17 PM
Thanks.
Title: Re: Sea Level Rise Projections and Maps
Post by: Tom_Mazanec on June 06, 2019, 08:14:36 PM
Here is something you don't often see reported about that Australian report we are discussing...the longer term sea level rise is 25 meters.
https://www.newshub.co.nz/home/world/2019/06/alarming-climate-report-says-25m-sea-level-rise-on-the-way.html
Title: Re: Sea Level Rise Projections and Maps
Post by: Aluminium on June 06, 2019, 10:05:11 PM
Pliocene: 400 ppm CO2, 2-3°C warmer, sea level 25 metres higher.
Title: Re: Sea Level Rise Projections and Maps
Post by: Sebastian Jones on June 06, 2019, 10:34:36 PM
Tom is correct- we rarely see these projections. Most projections speak of sea level rise by 2100. "Only" 80 years away. We acknowledge that anthropogenic climate change really got going with the advent of industrialization 160 odd years ago. So it is strange that standard projections do not go at least that far out, even if what we really need are projections about when we shall see the 25m of sea level rise.
Title: Re: Sea Level Rise Projections and Maps
Post by: Klondike Kat on June 07, 2019, 03:06:54 PM
Tom is correct- we rarely see these projections. Most projections speak of sea level rise by 2100. "Only" 80 years away. We acknowledge that anthropogenic climate change really got going with the advent of industrialization 160 odd years ago. So it is strange that standard projections do not go at least that far out, even if what we really need are projections about when we shall see the 25m of sea level rise.
They did not give a time expectancy for 25m, only that it could rise eventually.
Title: Re: Sea Level Rise Projections and Maps
Post by: Sebastian Jones on June 07, 2019, 06:38:04 PM
Tom is correct- we rarely see these projections. Most projections speak of sea level rise by 2100. "Only" 80 years away. We acknowledge that anthropogenic climate change really got going with the advent of industrialization 160 odd years ago. So it is strange that standard projections do not go at least that far out, even if what we really need are projections about when we shall see the 25m of sea level rise.
They did not give a time expectancy for 25m, only that it could rise eventually.

If humanity is serious about adaptation, it needs to start planning for 25m. Of course there is lots of uncertainty about the schedule, but there is little doubt that unless something happens to crash CO2 levels, we have locked a Pliocene like climate and are on our way to assuring another PETM. At the very least we should be able to come up with a range. There are real world implications here!
Title: Re: Sea Level Rise Projections and Maps
Post by: Tom_Mazanec on June 08, 2019, 11:23:30 PM
If we push AGW that extreme, what were sea levels in the PETM?
Title: Re: Sea Level Rise Projections and Maps
Post by: SteveMDFP on June 09, 2019, 12:01:38 AM
If we push AGW that extreme, what were sea levels in the PETM?

"Paleogene sea level should have been 70– 80 m higher than
present-day, assuming a similar volume for the overall ocean
basin, or upward of 120 m higher than present-day, if this
volume was significantly smaller"

Eustatic variations during the Paleocene-Eocene greenhouse world
https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2008PA001615 (https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2008PA001615)
Title: Re: Sea Level Rise Projections and Maps
Post by: pietkuip on June 09, 2019, 01:35:06 AM
A sketch of the Area Formerly Known As The Netherlands in the year 2300:
(https://www.vn.nl/wp-content/uploads/sites/3/2019/03/VN_NL2300_English.jpg)

From this article: https://www.vn.nl/rising-sea-levels-netherlands
Title: Re: Sea Level Rise Projections and Maps
Post by: Tor Bejnar on June 09, 2019, 03:37:35 AM
I could only see a sliver of the top of the sketch, so I went to the site, pretended to be able to agree to something in Dutch, and found the sketch, mostly reproduced below (I hope). Interesting article (in English).  Edit:  Now I can see the sketch above, so I'm deleting my version...
Title: Re: Sea Level Rise Projections and Maps
Post by: Klondike Kat on June 13, 2019, 03:13:21 PM
Although some scientists are predicting a sea level rise of 1m or more by 2100, other physicists state that the probably maximum for this century is 80cm, based on ice flow limitations.

https://phys.org/tags/sea+level+rise/
Title: Re: Sea Level Rise Projections and Maps
Post by: SteveMDFP on June 13, 2019, 03:26:14 PM
Although some scientists are predicting a sea level rise of 1m or more by 2100, other physicists state that the probably maximum for this century is 80cm, based on ice flow limitations.

https://phys.org/tags/sea+level+rise/

I don't see any such study at that link.  Quite a few articles there contradict your assertion.
Title: Re: Sea Level Rise Projections and Maps
Post by: Klondike Kat on June 13, 2019, 03:58:21 PM
Although some scientists are predicting a sea level rise of 1m or more by 2100, other physicists state that the probably maximum for this century is 80cm, based on ice flow limitations.

https://phys.org/tags/sea+level+rise/

I don't see any such study at that link.  Quite a few articles there contradict your assertion.
No, it does not link to a specific study.
Title: Re: Sea Level Rise Projections and Maps
Post by: SteveMDFP on June 13, 2019, 04:02:41 PM
Although some scientists are predicting a sea level rise of 1m or more by 2100, other physicists state that the probably maximum for this century is 80cm, based on ice flow limitations.

https://phys.org/tags/sea+level+rise/

I don't see any such study at that link.  Quite a few articles there contradict your assertion.
No, it does not link to a specific study.

So, what is the basis for your assertion "other physicists state that the probably maximum for this century is 80cm, based on ice flow limitations" ?
Title: Re: Sea Level Rise Projections and Maps
Post by: Klondike Kat on June 13, 2019, 06:29:54 PM
Although some scientists are predicting a sea level rise of 1m or more by 2100, other physicists state that the probably maximum for this century is 80cm, based on ice flow limitations.

https://phys.org/tags/sea+level+rise/

I don't see any such study at that link.  Quite a few articles there contradict your assertion.
No, it does not link to a specific study.

So, what is the basis for your assertion "other physicists state that the probably maximum for this century is 80cm, based on ice flow limitations" ?

Do you mean besides the statement at phys.org stated such?
Title: Re: Sea Level Rise Projections and Maps
Post by: SteveMDFP on June 13, 2019, 06:39:11 PM
Although some scientists are predicting a sea level rise of 1m or more by 2100, other physicists state that the probably maximum for this century is 80cm, based on ice flow limitations.

https://phys.org/tags/sea+level+rise/

I don't see any such study at that link.  Quite a few articles there contradict your assertion.
No, it does not link to a specific study.

So, what is the basis for your assertion "other physicists state that the probably maximum for this century is 80cm, based on ice flow limitations" ?

Do you mean besides the statement at phys.org stated such?

Oh!  You were referring to the sidebar:  "However, models of glacial flow in the smaller present-day ice sheets show that a probable maximum value for sea level rise in the next century is 80 centimeters, based on limitations on how quickly ice can flow below the equilibrium line altitude and to the sea.
This text uses material from Wikipedia, licensed under CC BY-SA"

Well, if you want to argue for a warmist perspective, I'd urge you to cite the *actual* source, not some rehashed version.  I can't find a clear statement on Wikipedia for this.  It's unclear whether the "smaller present-day ice sheets" includes Greenland and Antarctica or not.  This would make a rather sizable difference in meaning.
Title: Re: Sea Level Rise Projections and Maps
Post by: Lennart van der Linde on June 13, 2019, 06:55:21 PM
Sounds like they may be referring to Pfeffer et al 2008:
ftp://soest.hawaii.edu/coastal/Coastal%20Geology%20Class%20GG420/Pfeffer%20sea%20level%20calving%202008.pdf

But I don't think that paper says 0.8m is an upper limit, just that it seems more plausible than 2m.
Over the decade since 2008 estimates of the potential Antarctic contribution to SLR have made a SLR of 2m seem less implausible, with a recent expert elicitation estimating the chance under high emissions about 10%:
https://www.pnas.org/content/116/23/11195

We'll probably find out eventually.
Title: Re: Sea Level Rise Projections and Maps
Post by: Tom_Mazanec on June 13, 2019, 08:44:03 PM
We'll probably find out eventually.

We will definitely find out on January 1, 2101.
Title: Re: Sea Level Rise Projections and Maps
Post by: Tor Bejnar on June 13, 2019, 09:47:04 PM
I suspect "we" will find out a decade before 1/1/2100.
Title: Re: Sea Level Rise Projections and Maps
Post by: RikW on June 14, 2019, 09:10:27 AM
yeah, but not the exact rise ;)

If medical science will have some breakthrough and I'll never move again, I'll have a coastal home in 1-3 centuries seeing the map of the netherlands
Title: Re: Sea Level Rise Projections and Maps
Post by: Klondike Kat on June 14, 2019, 02:12:05 PM
yeah, but not the exact rise ;)

If medical science will have some breakthrough and I'll never move again, I'll have a coastal home in 1-3 centuries seeing the map of the netherlands

Possibly sooner.  If we get those type of medical breakthroughs, the global population will never peak.
Title: Re: Sea Level Rise Projections and Maps
Post by: dnem on June 14, 2019, 03:23:51 PM
yeah, but not the exact rise ;)

If medical science will have some breakthrough and I'll never move again, I'll have a coastal home in 1-3 centuries seeing the map of the netherlands

Possibly sooner.  If we get those type of medical breakthroughs, the global population will never peak.

Never?!
Title: Re: Sea Level Rise Projections and Maps
Post by: Aluminium on June 14, 2019, 04:22:37 PM
Theoretically, there is kind of progressions which have a limit but don't have a maximum.
Title: Re: Sea Level Rise Projections and Maps
Post by: dnem on June 14, 2019, 04:32:25 PM
Theoretically, there is kind of progressions which have a limit but don't have a maximum.

You really think he meant that the human population will approach an asymptote?!
Title: Re: Sea Level Rise Projections and Maps
Post by: Sebastian Jones on June 14, 2019, 04:49:21 PM
Theoretically, there is kind of progressions which have a limit but don't have a maximum.

You really think he meant that the human population will approach an asymptote?!
"Fortunately" we still have the catastrophic effects of the climate crisis to counter the potential for an asymptotic population trend....
Title: Re: Sea Level Rise Projections and Maps
Post by: oren on June 15, 2019, 12:05:12 AM
I think KK meant medical breakthroughs could modify the expected trajectory of human population, preventing the expected peaking, increasing pressure on the environment, and thus bringing about sharp sea level rise much sooner. Hope I understood correctly.
Population will off course peak due to the adverse results of climate change and the rest of the carrying capacity issues. The higher you fly, the faster you fall.
Title: Re: Sea Level Rise Projections and Maps
Post by: bligh8 on June 15, 2019, 02:10:03 PM
Re:  The higher you fly, the faster you fall.

Terminal velocity for humans is about 240kph, so if one is falling over salt water with SLR in mind one would go splat somewhat sooner.
Title: Re: Sea Level Rise Projections and Maps
Post by: Tom_Mazanec on September 01, 2019, 01:46:26 AM
I'll repost my link to the model of Earth 3000 AD ("Dubia") here because I realized this is where it really belonged:
http://www.worlddreambank.org/D/DUBIA.HTM
Title: Re: Sea Level Rise Projections and Maps
Post by: bbr2314 on September 01, 2019, 02:32:12 AM
I'll repost my link to the model of Earth 3000 AD ("Dubia") here because I realized this is where it really belonged:
http://www.worlddreambank.org/D/DUBIA.HTM
Melting 100% of Greenland by 3000AD would require approximately .1% losses each year (based on current mass balance). That would mean that the entirety of the SMB loss between 2002 and 2019, which I believe to be .1%, would be repeated EACH AND EVERY YEAR. That is a loss of 4,000 GT a year of ice, approximately 15X the mass loss we see each year today.

I feel like the impacts of such MASSIVE ice loss are always lost in these projections. If the changes since 2002 -- and 2012 in particular -- are enough to result in changes we have seen to date, a melt year where Greenland loses 2X the volume of its record loss year to date is going to potentially have exponentially worse impacts than what we have already witnessed. Even if the impacts aren't exponential, at what threshold does mass loss result in year without a summer for much of the NATL? 3X current worst to date? 4X? 5? 10X? 20X? Because if projections are correct we are going to hit each and every one of those numbers at some point in the relatively near future. And I do not believe that will be without dire consequence that temporarily halts or stalls the melting of the ice sheet (the only good result).