Support the Arctic Sea Ice Forum and Blog

Author Topic: Conservative Scientists & its Consequences  (Read 589296 times)

Michael Hauber

  • ASIF Middle Class
  • Posts: 757
    • View Profile
  • Liked: 23
  • Likes Given: 4
Re: Conservative Scientists & its Consequences
« Reply #150 on: November 07, 2014, 08:36:27 AM »
Another consequence of the conservatism is the overton window.  This is the propaganda technique of attempting to frame the debate as being between a totally unreasonable position and your opponents position so that the middle position is close to your desired position.

We have a debate between scientists trying to be as close to the truth as they can be, and anti-climate action propagandists who are lieing through their teeth to claim that Co2 has no effect and even if it did it would be beneficial etc.  So the public can easily fall into the comfortable compromise solution of deciding the truth is somewhere in between and believe that climate change is some sort of problem, but not nearly as much as the alarmists make out.

Of course by this logic I should be happy that there are people who are trying to push positions on climate change far more alarmist than I think correct.  This will tend to push the overton window in this direction so that the middle ground compromise falls closer to the truth.  I find this deeply unsettling....
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #151 on: November 07, 2014, 08:55:03 AM »
Michael,

You say:
Quote
there are people who are trying to push positions on climate change far more alarmist than I think correct

And:
Quote
In my opinion there is no scientific backing for a target of 1.5 or 2.  The only target I think the science justifies is 0. The carbon budget should be as low as possible.

Can you give some examples of people who're pushing positions far more alarmist than you think justified?

You think the carbon budget should be as low as possible, as do I, and the warming target should be 0 degrees, which implies taking a lot of carbon out of the air. Many people, not me, would call that very alarmist, so do you know people who're pushing even more radical positions?

viddaloo

  • ASIF Upper Class
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Conservative Scientists & its Consequences
« Reply #152 on: November 07, 2014, 08:59:46 AM »
1) I seem to have gotten sucked into a sensitive topic. I didn't notice (mea maxima culpa) that i was posting on a thread about conservative scientists and consequences ("its" is the wrong possessive here, and the word might better be dropped, but i digress.)

«Conservative Scientists & its Consequences» may sound a bit strange, but I read it as (The Problem of) Conservative Scientists & its (the Problem's) Consequences. A (too) simple fix would be to write «Conservative Scientists & their Consequences», but the consequences do not belong to the individual scientists, they are consequences of a problem. Best solution would probably be to rewrite to «Conservative Science & its Consequences».

I think the (future) flooding of Netherlands and the 2011 flooding of Fukushima serve as best concrete cases for thinking about 'alarmism' and conservatism. Society needs to plan for the worst, especially when nuclear facilities are involved. Can we learn how to shut down the plants quicker, so it doesn't take decades?
[]

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #153 on: November 07, 2014, 09:33:50 AM »
On flooding: how about Bangladesh, Vietnam, Indonesian coasts, parts of China, many small island states? Or New York, Boston?

wili

  • ASIF Upper Class
  • Posts: 2374
    • View Profile
  • Liked: 44
  • Likes Given: 224
Re: Conservative Scientists & its Consequences
« Reply #154 on: November 07, 2014, 10:50:19 AM »
Flooding is happening now in Rome, right after similar events in Northern Italy and SE France:

Red alert Rome braced for ‘water bombs’
Quote
With the civil protection department expecting torrential rain to lead to “water bombs”, the authorities decided to close schools and monuments in Rome Thursday. Thursday. Rome Prefect Giuseppe Pecoraro earlier said that the weather forecasts were “unprecedented” and suggested Romans avoid leaving their homes. …

http://www.gazzettadelsud.it/news/english/115572/Red-alert-Rome-braced-for--water-bombs-.html


Violent storms lash the French Riviera


http://www.thelocal.fr/galleries/news/in-images-violent-storms-lash-french-riviera

    Tuscany residents saved as floods hit Italy

    http://www.thelocal.it/20141105/tuscany-residents-saved-as-floods-hit-italy
       

        France deluged with massive rainfall


        Nice got 160mm in 24 hours.

        http://www.bbc.com/weather/features/29921484

(Thanks, as often, to COBob for pointing these out over at robertscribbler's blog.)
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Laurent

  • ASIF Governor
  • Posts: 2527
    • View Profile
  • Liked: 0
  • Likes Given: 3
Re: Conservative Scientists & its Consequences
« Reply #155 on: November 07, 2014, 12:57:29 PM »
I try to calculate how many nuclear bombs per second is that 7.1 10y22 Joule.
Wikipedia says little boy was : 67 TJ   http://en.wikipedia.org/wiki/Little_Boy
Per year : 7.1 10y22 / 35 = 2,028571429×10²¹ Joule
Per day : /360 = 5,634920635×10¹⁸ Joule
Per hour : /24 = 2,347883598×10¹⁷ Joule
Per secondes : /3600 = 6,521898883×10¹³ Joule
Per nuclear bombe : /67.10y12 = 0,973417744 Nuclear Bombs/seconde

That's not 4 nuclear bombs per seconds used on the Neven blog, skeptical and other... is there underestimation somewhere ?

Quote
the durack et.al estimates are from 1970 to 2004 (34 years)  and estimate an increase in OHC for the southern hemisphere of 2.2 to 7.1 * 10^22 joules

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #156 on: November 07, 2014, 01:52:36 PM »
Would that be the average over 35 years for the Southern Hemisphere?

The four bombs per second would be over the last decade or so for the whole planet, I guess.

mark

  • ASIF Lurker
  • Posts: 59
    • View Profile
  • Liked: 0
  • Likes Given: 0
Re: Conservative Scientists & its Consequences
« Reply #157 on: November 07, 2014, 01:56:37 PM »
Vid you beat me to it, the conversation here is much better debated under 'conservative science' as that is the end result. It is unfair to categorise or stigmatise scientists as conservative as I am sure that in all these circumstances there are conservatives and non conservatives  better still to give them a good or bad label as that is simpler and more apt as mostly they are constrained by their guidelines.

Certainly the target should be for 0 even when this is totally unachievable given all the variables. However the equilibrium point to aim this 0 at is more difficult to define. To set the 0 point in pre industrial times is not ideal as it was too cold then and crop production in that climate would be compromised, to go colder would mean drastic compromises with the population that would be arduous to achieve. So the 0 would need to be set probably at around the temperature we are at now, which would mean a loss of some land mass but at a food production rate that can support the world ecology. This would lead on to then say should the worlds population be set at its current level and then take this point as '0' as we cannot go back to preindustrial population levels without a very difficult adjustment period.

In other words to set a zero to suit humankind would mean setting a zero point for many other aspects of human behaviour. Shift the population upwards and a corresponding shift of the climate 0 target would need to be made too. Where this 0 point is in both climate and human society is very open to discussion and worthy of yet another thread. Should we set the climate/carbon 0 at preindustrial levels and make adjustments of population levels downwards (not necessarily to match pre industrial levels as we are far more efficient now) or should we set the population levels at todays and work out an equilibrium point for temperature and CO2 that matches our needs.

So is the 0 target realistic as there is cyclical variability, over what period would one set a 0 target - a decade, century, millennia. It could only be set if we are sure we are basing it on a period where all amplitudes are known. So now one comes back to what would be a conservative/non-conservative target?

These points are rhetorical - I am not setting a position. Its just that the conversation has moved to a point where there is a gap in whats being said

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #158 on: November 07, 2014, 02:13:41 PM »
Mark, good points.

Current temperature would mean more ice melting, since arctic and other ice is not in equilibrium with current temps. So to stop the ice from melting further we would even need some cooling for a while, I suppose?

Hansen c.s. propose 350 ppm CO2 as an initial target (by 2150?), or even lower if shown necessary later. That would probably still mean some warming for a while and then some cooling, if slow feedbacks, such as melting ice and carbon feedbacks, are slow enough.

This all depends on how much carbon we can take out of the atmosphere and at what speed.

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #159 on: November 07, 2014, 02:18:00 PM »
See Hansen et al 2013 for further exploration of these questions:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0081648

This article still seems on the conservative (=risky) side, since it does not take carbon feedbacks into account, if I'm not mistaken.

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #160 on: November 07, 2014, 02:31:57 PM »
See specifically this quote from Hansen et al 2013:
"most climate simulations, including ours above and those of IPCC, do not include slow feedbacks such as reduction of ice sheet size with global warming or release of greenhouse gases from thawing tundra. These exclusions are reasonable for a ~1°C scenario, because global temperature barely rises out of the Holocene range and then begins to subside. In contrast, global warming of 2°C or more is likely to bring slow feedbacks into play. Indeed, it is slow feedbacks that cause long-term climate sensitivity to be high in the empirical paleoclimate record."

So it seems they think the risk of slow feedbacks kicking in is limited for their radical mitigation scenario. Current warming/forcing would still be faster/stronger than in the past however, so there could still be a risk of slow feedbacks amplifying the warming more than calculated by Hansen et al. That's why 350 ppm is their initial target, to be adjusted if needed/possible.
« Last Edit: November 07, 2014, 02:43:48 PM by Lennart van der Linde »

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #161 on: November 07, 2014, 02:51:07 PM »
BTW, I suppose nobody here thinks Hansen et al are being either alarmist or overly conservative? Just checking.

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #162 on: November 07, 2014, 03:06:08 PM »
P.S. I consider Hansen et al 2013 the single best scientific article connecting the dots of the climate crisis that I know of, much clearer and less conservative (=risky) than the IPCC-reports. But if anyone knows any even better or equally good articles, let us know. Of course Hansen et al also prescribe targets and policy options, which IPCC cannot do, but still, they make the risks of less ambitious targets much clearer than IPCC has been allowed to do.

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #163 on: November 07, 2014, 04:12:15 PM »
Here a nice news article by Fred Pearce on the various carbon budgets floating around, including the 130 GtC of Hansen et al:
http://www.resilience.org/stories/2014-11-07/what-is-the-carbon-limit-that-depends-who-you-ask

So it actually depends more on your temperature target and how much you want to risk missing it, than on who you ask. And on some assumptions about emissions of non-CO2 gases, carbon uptake and (not included in Pearce's article) potential positive carbon feedbacks.

wili

  • ASIF Upper Class
  • Posts: 2374
    • View Profile
  • Liked: 44
  • Likes Given: 224
Re: Conservative Scientists & its Consequences
« Reply #164 on: November 07, 2014, 04:19:09 PM »
"nobody here thinks Hansen et al are being either alarmist or overly conservative?"

I haven't read all of Hansen's work. He seems to be one of the best on many levels. But all scientists have their areas of expertise. I think on abrupt SLR risks Box, Alley and some others have spoken more forcefully than Hansen has (at least that I know of)--ASLR could of course speak much more knowledgeably on that subject than I could.

But I don't expect any one scientist to lay out all the possibilities for catastrophic events of every kind.

I have problems with the whole 'carbon budget' thing, too. We don't really have any 'budget' left--we're way overdrawn.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #165 on: November 07, 2014, 06:06:10 PM »
Quote
I think on abrupt SLR risks Box, Alley and some others have spoken more forcefully than Hansen has (at least that I know of)

I'm not sure. Maybe Box, Alley and others speak with some more authority on the risks of abrupt SLR, as glaciologists, but my impression is Hansen has stressed those risks maybe more forcefully than any other scientist, even to the point where Alley sort of unjustly ridiculed him, as Hansen & Sato 2012 shows:
http://www.springer.com/cda/content/document/cda_downloaddocument/9783709109724-c1.pdf?SGWID=0-0-45-1328875-p174243184

They say:
"Alley (2010) reviewed projections of sea level rise by 2100, showing several clustered around 1 m and one outlier at 5 m, all of these approximated as linear in his graph. The 5-m estimate is what Hansen (2007) suggested was possible under IPCC’s BAU climate forcing. Such a graph is comforting—not only does the 5-m sea level rise disagree with all other projections, but its half-meter sea level rise this decade is clearly preposterous. However, the fundamental issue is linearity vs. non- linearity. Hansen (2005, 2007) argues that amplifying feedbacks make ice sheet disintegration necessarily highly nonlinear and that IPCC’s BAU forcing is so huge that it is difficult to see how ice shelves would survive. As warming increases, the number of ice streams contributing to mass loss will increase, contributing to a nonlinear response that should be approximated better by an exponential than by a linear fit. Hansen (2007) suggested that a 10-year doubling time was plausible and pointed out that such a doubling time, from a 1-mm/year ice sheet contribution to sea level in the decade 2005–2015, would lead to a cumulative 5-m sea level rise by 2095."

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #166 on: November 07, 2014, 06:15:39 PM »
Just to add: because of negative feedbacks, such as iceberg cooling of the ocean, and also possibly because of kinematic constraints, Hansen & Sato seem to regard about 2,5 meters by 2100 as the upper limit.

wili

  • ASIF Upper Class
  • Posts: 2374
    • View Profile
  • Liked: 44
  • Likes Given: 224
Re: Conservative Scientists & its Consequences
« Reply #167 on: November 07, 2014, 07:19:34 PM »
I'm confused. Is the long quote by Alley? If so, the only thing he seems to ridicule is the notion that a .5 meter gain this decade is likely, which seems pretty reasonable.

What I've seen Alley talk about is the fact that we don't know whether water getting under WAIS will cause a rather sudden large SLR. He says it may be unlikely, but we need to plan for unlikely but possible catastrophic developments.
"A force de chercher de bonnes raisons, on en trouve; on les dit; et après on y tient, non pas tant parce qu'elles sont bonnes que pour ne pas se démentir." Choderlos de Laclos "You struggle to come up with some valid reasons, then cling to them, not because they're good, but just to not back down."

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #168 on: November 07, 2014, 08:14:39 PM »
No, the quote is from Hansen & Sato 2012. I read it as saying that Alley did not take enough care to accurately present Hansen's conjecture of potentially exponentially growing SLR. That made Hansen's conjecture seem 'clearly preposterous', maybe unintentionally, but still.

And yes, Alley has done a good job of explaining the potential risk of abrupt SLR, up to the point where he seems to not completely exclude a risk of about 3m of SLR by 2100 by a collapse of WAIS.

Laurent

  • ASIF Governor
  • Posts: 2527
    • View Profile
  • Liked: 0
  • Likes Given: 3
Re: Conservative Scientists & its Consequences
« Reply #169 on: November 07, 2014, 08:20:25 PM »
That should fuel (lot of carbon) your brains...?
New study questions the accuracy of satellite atmospheric temperature estimates
http://www.theguardian.com/environment/climate-consensus-97-per-cent/2014/nov/07/new-study-disputes-satellite-temperature-estimates

Michael Hauber

  • ASIF Middle Class
  • Posts: 757
    • View Profile
  • Liked: 23
  • Likes Given: 4
Re: Conservative Scientists & its Consequences
« Reply #170 on: November 07, 2014, 08:24:15 PM »
BTW, I suppose nobody here thinks Hansen et al are being either alarmist or overly conservative? Just checking.

Personally I think his science is good, but I'm not so sure about some of the language, which is of course a much more subjective issue.

In one spot he says that the impacts of climate change at 2 degrees are 'highly deletorious' and 'dangerous'.  Which I agree with.  Significant negative impacts.  And dangerous in the same sense that driving down the highway at well over the speed limit is dangerous - something really really bad might happen.  Then he says 2 degrees would be disastrous.  Disastrous to me is like driving down the highway at well over the speed limit and then crashing into the tree.  Disastrous to me is something really really bad will happen, and I'm firmly in the may happen camp for climate change.
Climate change:  Prepare for the worst, hope for the best, expect the middle.

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #171 on: November 07, 2014, 10:24:07 PM »
In their abstract Hansen et al say:
"2°C global warming, would spur “slow” feedbacks and eventual warming of 3–4°C with disastrous consequences"

In the discussion section of the article itself they say:
"Fossil fuel emissions of 1000 GtC, sometimes associated with a 2°C global warming target, would be expected to cause large climate change [of 3-4 degrees; my addition] with disastrous consequences. The eventual warming from 1000 GtC fossil fuel emissions likely would reach well over 2°C, for several reasons. With such emissions and temperature tendency, other trace greenhouse gases including methane and nitrous oxide would be expected to increase, adding to the effect of CO2. The global warming and shifting climate zones would make it less likely that a substantial increase in forest and soil carbon could be achieved. Paleoclimate data indicate that slow feedbacks would substantially amplify the 2°C global warming. It is clear that pushing global climate far outside the Holocene range is inherently dangerous and foolhardy."

In the main text in between they say:
"distinctions between pathways aimed at ~1°C and 2°C warming are much greater and more fundamental than the numbers 1°C and 2°C themselves might suggest. These fundamental distinctions make scenarios with 2°C or more global warming far more dangerous; so dangerous, we suggest, that aiming for the 2°C pathway would be foolhardy...
let us compare the 1°C (500 GtC fossil fuel emissions) and the 2°C (1000 GtC fossil fuel emissions) scenarios. Global temperature in 2100 would be close to 1°C in the 500 GtC scenario, and it is less than 1°C if 100 GtC uptake of carbon by the biosphere and soil is achieved via improved agricultural and forestry practices (Fig. 9). In contrast, the 1000 GtC scenario, although nominally designed to yield a fast-feedback climate response of ~ 2°C, would yield a larger eventual warming because of slow feedbacks, probably at least 3°C."

So 2 degrees would be disastrous because it would probably imply at least 3 degrees.

jai mitchell

  • ASIF Upper Class
  • Posts: 1950
    • View Profile
  • Liked: 31
  • Likes Given: 7
Re: Conservative Scientists & its Consequences
« Reply #172 on: November 07, 2014, 11:16:54 PM »

So 2 degrees would be disastrous because it would probably imply at least 3 degrees.

3 or 4 as Hansen said.

However, the feedbacks associated with carbon cycle and slow response as well as albedo feedbacks in the arctic and Antarctica (later on) will also contribute in the higher end scenarios.  This is why six degrees of warming will lead to 12 degrees. 

Here is a writeup I did on the subject earlier.  I see this as the worst case scenario, however, In it I overestimated sea level rise due to expansion by about 20-40 meters (by 2300)

in my opinion, this is the kind of dialogue that we need to be engaged in.

http://forum.arctic-sea-ice.net/index.php/topic,77.msg35993.html#msg35993

If you consider current collapse rates of the arctic sea ice and the Amazon basin, as well as mid to high level estimations of current radiative forcing of greenhouse gases (without aerosols included, knowing that they are temporarily cooling).  We are already well past 2C of warming by 2100.
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

viddaloo

  • ASIF Upper Class
  • Posts: 1302
  • Hardanger Sometimes
    • View Profile
  • Liked: 1
  • Likes Given: 0
Re: Conservative Scientists & its Consequences
« Reply #173 on: November 07, 2014, 11:59:36 PM »
Just to add: because of negative feedbacks, such as iceberg cooling of the ocean, and also possibly because of kinematic constraints, Hansen & Sato seem to regard about 2,5 meters by 2100 as the upper limit.

How sure are we that the melting of an iceberg will be a net negative feedback? True, the melt of a 1 km³ iceberg would cool surrounding waters at first, but then it would allow for more solar warming of that ocean area, less albedo etc. Within a year it might be a net positive feedback, no?
[]

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #174 on: November 08, 2014, 09:10:46 AM »
On iceberg cooling Hansen & Sato say it is indeed temporary (p.41):

"Iceberg Cooling Effect
Exponential change cannot continue indefinitely. The negative feedback terminating exponential growth of ice loss is probably regional cooling due to the thermal and freshwater effects of melting icebergs. Temporary cooling [emphasis added] occurs as icebergs and cold fresh glacial meltwater are added to the Southern Ocean and the North Atlantic Ocean.

As a concrete example, Fig. 9 shows the global temperature change in simulations with GISS modelE (Schmidt et al. 2006; Hansen et al. 2007c) with and without the melting iceberg effect. GHGs follow the A1B scenario, an intermediate business-as-usual scenario (IPCC 2001, 2007; see also Figs. 2 and 3 of Hansen et al. 2007b). Ice melt rate is such that it contributes 1 mm/year to sea level in 2010, increasing with a 10-year doubling time; this melt rate constitutes 0.034 Sv (1 Sverdrup ¼ 1 million m3/s) in 2065 and 0.1 Sv in 2080. Half of this meltwater is added in the North Atlantic and half in the Southern Ocean. By 2065, when the sea level rise (from ice melt) is 60 cm relative to 2010, the cold freshwater reduces global mean warming (relative to 1880) from 1.86C to 1.47C. By 2080, when sea level rise is 1.4 m, global warming is reduced from 2.19C to 0.89C.

These experiments are described in a paper in preparation, which includes other GHG scenarios, cases with ice melt in one hemisphere but not the other, and investigation of the individual effects of freshening and cooling by icebergs (the freshening is more responsible for the reduction of global warming).

Note that the magnitude of the regional cooling is comparable to that in “Heinrich” events in the paleoclimate record (Bond et al. 1992), these events involving massive iceberg discharge at a rate comparable to that in our simulations. Given that the possibility of sea level rise of the order of a meter is now widely accepted, it is important that simulations of climate for the twenty-first century and beyond include the iceberg cooling effect.

Detailed consideration of the climate effects of freshwater from ice sheet disintegration, which has a rich history (Broecker et al. 1990; Rahmstorf 1996; Manabe and Stouffer 1997), is beyond the scope of our present chapter. However, we note that the temporary reduction of global warming provided by icebergs is not likely to be a blessing. Stronger storms driven by increased latitudinal temperature gradients, combined with sea level rise, likely will produce global havoc.

It was the prospect of increased ferocity of continental-scale frontal storms, with hurricane-strength winds powered by the contrast between air masses cooled by ice melt and tropical air that is warmer and moister than today, which gave rise to the book title “Storms of My Grandchildren” (Hansen 2009)."


Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #175 on: November 08, 2014, 10:05:11 AM »
Jai,
Do I understand correctly that you think 110m of SLR possible in the North Atlantic by 2300?

I'm wondering what that's based on.

The maximum possible global mean SLR would be 70-80m, with 5-10m thermal expansion included, as far as I know. Add maybe 20-25% in the North Atlantic for gravitational effects and circa 85-100m would be the maximum regionally.

But by 2300? I think even Jim Hansen would think more than 10m of SLR per century impossible to imagine. So about one millennium would be the minimum time required for the maximum possible SRL. Most experts would probably say it would take at least a few millennia. That may still be conservative, so an underestimate, but less than one millennium would seem hard to imagine, if only because it would take the ocean at least this long to reach thermal equilibrium.

Or am I missing something?
« Last Edit: November 08, 2014, 10:23:13 AM by Lennart van der Linde »

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #176 on: November 08, 2014, 01:07:09 PM »
I think Kopp et al 2014 are doing a good job showing a full spectrum of estimated probabilities for future SLR up to 2200:
http://onlinelibrary.wiley.com/doi/10.1002/2014EF000239/full

See their table 1 in particular, which shows 9.5m in 2200 as an upper limit with a chance of less than 0.1%. Extrapolating from 2200 it seems maybe 20m would be the upper limit for 2300. This could be about Jim Hansen's worst-case estimate as well.

Other papers don't estimate such small chances, but speak of 5% or 2.5% estimated worst-case probabilities,. For example, Jevrejeva et al 2014 and Rohling et al 2013 estimate 1.8m by 2100 as a worst-case risk with 5% and 2.5% chance respectively. Rohling et al estimate a 2.5% chance of about 9m by 2300. So maybe for Jevrejeva et al 9m by 2300 would have about a 5% chance?

Meehl et al 2012 estimated 9-10m by 2300 as a worst-case, without specifying any probability. In fact they said this is impossible:
"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.”

Horton et al 2014 asked a group of about 70-90 SLR-experts for their worst-case estimates for 2300:
http://www.sciencedirect.com/science/article/pii/S0277379113004381

About 5% of those responding (4 out 72) estimated a 5% chance of 9m or more by 2300, with 15m as the highest estimate. So for a 2.5% or 1% chance the highest individual expert-estimate may indeed be about 20m by 2300.

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #177 on: November 08, 2014, 01:56:53 PM »
See this post and following ones for attached figures from the papers referred to above:
http://forum.arctic-sea-ice.net/index.php/topic,1053.msg39377.html#msg39377

My conclusion so far: there's maybe a chance of roughly 0.01% of 20m of SLR by 2300 under BAU.

jai mitchell

  • ASIF Upper Class
  • Posts: 1950
    • View Profile
  • Liked: 31
  • Likes Given: 7
Re: Conservative Scientists & its Consequences
« Reply #178 on: November 08, 2014, 06:38:50 PM »
I try to calculate how many nuclear bombs per second is that 7.1 10y22 Joule.
Wikipedia says little boy was : 67 TJ   http://en.wikipedia.org/wiki/Little_Boy
Per year : 7.1 10y22 / 35 = 2,028571429×10²¹ Joule
Per day : /360 = 5,634920635×10¹⁸ Joule
Per hour : /24 = 2,347883598×10¹⁷ Joule
Per secondes : /3600 = 6,521898883×10¹³ Joule
Per nuclear bombe : /67.10y12 = 0,973417744 Nuclear Bombs/seconde

That's not 4 nuclear bombs per seconds used on the Neven blog, skeptical and other... is there underestimation somewhere ?

Quote
the durack et.al estimates are from 1970 to 2004 (34 years)  and estimate an increase in OHC for the southern hemisphere of 2.2 to 7.1 * 10^22 joules

Laurent,

The additional heat accumulation found in Durack et. al. is on top of the 4 bombs per second estimation.  In addition, the extra heat accumulation was observed over a 34 year period, not a single year.

The amount of heat added to the earth's biosphere each second is measured on the TOA analysis.  My estimations of TOA show that before Durack et. al TOA was about .7 Watts per meter squared (according to Nuccitelli et. al. and Hansen & Soto (2010))  after Durack et. al, the total heat accumulation is between 10% and 30% higher so current TOA is increased accordingly.



full image here:  http://oi58.tinypic.com/2ex60ip.jpg


However, if my observations are correct and the cause of the increased heat accumulation in the southern oceans is due to underestimations of the current aerosol forcing, then this means that the amount of total forcing (less aerosol effects) is much higher.

At this point, it should be noted that the anthropogenic aerosols will eventually go away and when they do, even using the potentially underestimated values, the amount of total incoming radiation from climate forcing will DOUBLE in intensity. (from .7-.9 to 1.5-2.0) 

If there is a significant underestimation it could go even higher (1.8-2.6)

Please note Top of Atmosphere is different from total anthropogenic forcing (as shown in the graph) as TOA subtracts the value of energy being lost as longwave (heat) to space.

Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

jai mitchell

  • ASIF Upper Class
  • Posts: 1950
    • View Profile
  • Liked: 31
  • Likes Given: 7
Re: Conservative Scientists & its Consequences
« Reply #179 on: November 08, 2014, 07:04:46 PM »
Jai,
Do I understand correctly that you think 110m of SLR possible in the North Atlantic by 2300?

I'm wondering what that's based on.

The maximum possible global mean SLR would be 70-80m, with 5-10m thermal expansion included, as far as I know. Add maybe 20-25% in the North Atlantic for gravitational effects and circa 85-100m would be the maximum regionally.

But by 2300? I think even Jim Hansen would think more than 10m of SLR per century impossible to imagine. So about one millennium would be the minimum time required for the maximum possible SRL. Most experts would probably say it would take at least a few millennia. That may still be conservative, so an underestimate, but less than one millennium would seem hard to imagine, if only because it would take the ocean at least this long to reach thermal equilibrium.

Or am I missing something?

80 meters by ice melt  http://pubs.usgs.gov/fs/fs2-00/
30-40 meters by gravity effects (extrapolated from http://www.tos.org/oceanography/archive/24-2_tamisiea.html)
20 meters by thermal expansion (an analog to the early cretaceous http://www.earth.ox.ac.uk/~tony/watts/for_studentship.jpg) This will continue to add to sea level rise until thermal equilibrium around 2600

=130- 140 meters total potential sea level rise (North America and Europe)  by 2300 under a runaway (but not venus effect) hothouse earth of +16C by 2200.  (note: I upped the estimate of thermal expansion again, I have not found a good estimate of this scenario anywhere but believe that the Cretaceous analog is good since it is globally averaged values and the gravitational effect in north America and Europe will compensate for not being at thermal equilibrium).

of course this is basically the total maximum potential, but assumes that temperatures stay well above freezing throughout the year at both poles and spike over 40C in summer.  Under this scenario, intensive hydrofracture due to Moulin coring and continuous internal heat deposition (over the complete ice sheet) http://scrippsscholars.ucsd.edu/hafricker/content/ice-shelf-disintegration-plate-bending-and-hydro-fracture-satellite-observations-and-model-r as well as sea level rise effects (shear crevasse formation and complete loss of buttressing by 2200 leading to cliff face effects after that)

Other factors included in this scenario but not in the Hansen scenario are contributions to forcing from hydrogen sulfide, clathrate release (resulting in increased tropospheric ozone and significantly longer CH4 residency times), increased carbon cycle effects and the complete halt of the Thermohaline, leading to significantly increased rates of ocean heat accumulation.
« Last Edit: November 08, 2014, 07:32:18 PM by jai mitchell »
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #180 on: November 08, 2014, 08:47:41 PM »
Jai,
IPCC 2013 only gives 66m of SLR if all land ice melted. See table 4.1:
http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter04_FINAL.pdf

The maximum gravity effect factor for the North Atlantic would be 1.4, so indeed more than the average 20-25% I assumed. Even with your 80m global mean SLR this would add about 30m at the most, not 40m. So 110m in total.

With IPCC's 66m it would add some 26m maximally. So that would make 92m.

Thermal expansion in RCP8.5 would be at most 65cm per century, I assume based on table 1 in Kopp et al 2014. So let's say 6m in a millennium.

In total that would be 72m globally and at most 98m in the North Atlantic.

I assumed RCP8.5 as representing BAU, with maybe 12 degrees C of global warming by 2300 and 10m of total global mean SLR.

But you assume 16 degrees C global warming by 2200. What radiative forcing would that be? And what rate of thermal expansion per century would that imply?

Let's assume about 1m per century, so about 3m by 2300. And maybe 6m by 2600. Your 20m thermal expansion by 2300 or 2600 seems hard to imagine.

But the main question still is: even with 16 degrees of warming by 2200, how would that melt all the ice by 2300? Or would that be the needed warming for the 20m of SLR by 2300 that has a roughly estimated likelihood of 0.01% (based on the references above, and assuming iceberg cooling and kinematic constraints would allow this)?

And how likely is 16 degrees by 2200? Would that also be a 0.01% chance, or more, or less?

jai mitchell

  • ASIF Upper Class
  • Posts: 1950
    • View Profile
  • Liked: 31
  • Likes Given: 7
Re: Conservative Scientists & its Consequences
« Reply #181 on: November 08, 2014, 09:46:58 PM »
Lennart

The answers to your questions are within my post(s)
here: https://forum.arctic-sea-ice.net/index.php/topic,1053.msg39676.html#msg39676
and here: http://forum.arctic-sea-ice.net/index.php/topic,77.msg35993.html#msg35993

here is the summary

Quote
But you assume 16 degrees C global warming by 2200. What radiative forcing would that be? And what rate of thermal expansion per century would that imply?

Hydrogen sulfide, increased carbon cycle feedbacks, increased tropospheric ozone, clathrate disassociation.   Primary thermal expansion would be significantly higher than IPCC report due to halting of the Thermohaline and hothouse conditions at the poles, leading to (significantly) increased rates of ocean heat accumulation (doubling or even tripling).

Quote
even with 16 degrees of warming by 2200, how would that melt all the ice by 2300?

non-linear polar region temperature rise to hothouse effects, massive hydraulic fracturing of ice shelf and cliff effects created after SLR increases sheer fracture and subsequent collapse of low-lying valley formations.  Ice shelf basal lubrication from continuous Moulin, high altitude rains over ice sheets, beginning to melt from the top down.  rapid ice sheet collapse due to lubrication, sheer/fracture, complete loss of buttress and rapid year-round sublimation.

-there is, obviously, no analog to this scenario within the paleoclimate record.



« Last Edit: November 08, 2014, 09:54:45 PM by jai mitchell »
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #182 on: November 08, 2014, 10:29:24 PM »
Let's have a little closer look at Rohling et al 2013:
http://www.nature.com/srep/2013/131212/srep03461/full/srep03461.html

How conservative is this analysis?

They assume a maximum rate of SLR of 4-5m per century, based on Meltwater Pulse 1A in the geological past. This was during the last deglaciation when there was about/almost 3 times as much ice on the planet as now and during earlier interglacials.

During those earlier interglacials maximum rates of SLR were maybe 1-2m per century as far as scientists can tell.

However, today's antropogenic climate forcing is maybe 10-100 times stronger than the natural forcings during the geological past. So could the rate of SLR become 10-100 times faster than the maximum rates estimated for past interglacials? Or would negative feedbacks and kinematic constraints impose a sort of maximum speed limit for melting ice and SLR?

As Hansen & Sato 2012 and Pfeffer et al 2008 suggest it seems reasonable to assume some such speed limit. So the question then is how likely is it to be more than the 4-5m per century that Rohling et al estimate to have about a 2.5% chance of occuring based on the geological past?

Personally, I don't see an immediate reason why say 7-10m per century would be impossible under a forcing 10-100 times stronger than ever before. For more than 10m per century the negative feedbacks and kinematic constraints may indeed be limiting factors. So maybe 10m per century would be a plausible speed limit?

Kopp et al 2014 also don't seem to exclude this possibility, but the likelihood they estimate as less than 0.1% (extrapolated from 2200 to 2300). Maybe this is comparable to Rohling et al?

Or maybe Rohling et al would give a somewhat higher chance for 10m per century, say 0.5%, since they estimate a 2.5% chance of 1.8m by 2100, whereas Kopp et al estimate about a 0.5% chance for such a SLR by 2100.

Jevrejeva et al 2014 even estimate a 5% chance of 1.8m by 2100 under BAU. So maybe the chance of 10m per century is more like 1%? Or would this still be too conservative?

If about 5 degrees of warming during the last deglaciation caused about 100m of SLR in about 10.000 years, then 5 degrees of warming now could probably cause at least 50m of SLR in the long run. But how long would this take?

Less than 10.000 years seems reasonable. But how much less? Would 5000 years be possible? That would imply an average SLR of 1m per century. So 5000 years seems quite conservative, since 1m per century was possible in the past under much smaller forcings than now.

So would 50m in a millennium be possible? That would imply about 6m per century from 2400 on. Maybe not impossible, although a question would be if that speed could be sustained for six centuries.

Or maybe a SLR of up to 10m per century would be possible for a few centuries and then the rate would slow down to say a few meters per century, comparable to the speed up and slow down during and after Meltwater Pulse 1A.

So if I stretch my layman's imagination to its current limits, I see 20m by 2300 and 40m by 2500 as the maximum possible SLR, and maybe 60-70m as the maximum by 3000.

Or if this would not be possible after all, then maybe 10m by 2300 and 20m by 2500, and maybe 30-35m by 3000?

In the past about 1m per century was a consequence of a temperature rise of about 0.05 degrees per century. If we now get several degrees of warming per century, could we eventually get a SLR of up to 10m per century, or even more? If not, why not?

And if so, why is the threat of this risk not being widely discussed? Is it because scientists are being conservative? Or is it because this is politically inconvenient to discuss?

Or is it because it is not physically possible after all? If so, can someone explain why not?

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #183 on: November 08, 2014, 10:48:58 PM »
Jai,
Ok, in your carbon cycle post your say:
Quote
We are going to force this earth to endure a 5-7C rise by 2100. This warming, on par with the warming that occurred from the depths of the last ice age to today, will create massive natural feedback mechanisms. This will be a fundamental transformation of the surface of the earth, on par with the transformation that occurred at the end of the last ice age, in the space of 100 years.

Yes, 5-7 degrees warming by 2100 seems quite possible. And yes, this would create massive natural feedbacks. But would these feedbacks be strong enough to cause another 10 degrees warming by 2200?

Or would we reach this 16 degrees total warming somewhat later, say around 2500? So 6 degrees by 2100, 10 degrees by 2200, 12 degrees by 2300, 14 degrees by 2400 and 16 degrees by 2500?

Or maybe later still, say at the end of this millennium.

I'm not saying your scenario is definitely impossible. I'm just wondering how physically plausible it is and how strong those natural feedbacks can be.

If you have references to scientific estimates (no doubt conservative ones), then that could be helpful.

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #184 on: November 08, 2014, 10:53:48 PM »
For example, I think IPCC estimates a maximum 250 GtC from permafrost melting by 2100, so how much extra warming would that cause? And how conservative do you consider this 250 GtC to be?

sidd

  • ASIF Governor
  • Posts: 4103
    • View Profile
  • Liked: 93
  • Likes Given: 0
Re: Conservative Scientists & its Consequences
« Reply #185 on: November 08, 2014, 11:09:38 PM »
"Or is it because it is not physically possible after all?"

I think if one does the coupled ice sheet/ice shelf/ocean/atmosphere models, the main difficulty is in getting enuf heat into the ice massifs to exceed 1-2m/century. I seem to recall some work estimating about a 1gigawatt/Km of coastline ocean heat influx flux into antarctica, and Box has excellent numbers on the number of extra joules going into GIS thru the albedo drop in recent years. His name is on some papers about GIS evolution in 21st century using MAR or RACMO2 for the atmosphere and I forget the ice model.

One may of course argue that the models are inadequate, but since they can reproduce (Gregoire, doi:10.1038/nature11257) MWP1A, one then has to come up with a better model. Which Hansen doesnt do, his (in the Russell model) ice sheet is not sophisticated,  he superposes supposed melt and then runs the global ocean/atmos model on top of that. But he should. If he don't someone else will, I await the results.

Right now the action is in regional atmos/ocean models coupled to a dynamic icesheet, but i dont think (corrections welcome) that anyone has done a global ocean/atmos model with reasonable complete dynamics (i include hydrology here) for  both GIS and AIS.

sidd

sidd

  • ASIF Governor
  • Posts: 4103
    • View Profile
  • Liked: 93
  • Likes Given: 0
Re: Conservative Scientists & its Consequences
« Reply #186 on: November 08, 2014, 11:37:00 PM »
To follow up, two brief comments:

1)  I believe Hansen's melt cooling effect is already seen in southern sea ice expansion
2) the point above reflects the subtleties in coupled heat and mass transport. one sees that the heat to melt grounded antarctic ice may, in some measure, be supplied from regions much further north than the original grounded ice regions themselves. Russell's model as used by Hansen, is i believe capable of doing this correctly if only (i keep saying, plaintively) it had realistic ice.  I suppose i should quit whining since i am not prepared to take a couple years off and do it myself.

sidd

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #187 on: November 09, 2014, 12:42:05 AM »
sidd,
Hansen used Russel's model to analyse sea level fluctuations over tens of millions of years and produced some better results for interglacials and the Pliocene than alternative models by De Boer et al. He suspects current ice sheet models to have too much hysteresis for climates warmer than now.

I'm not sure, but maybe an example of such a model is Goelzer et al 2012:
http://iopscience.iop.org/1748-9326/7/4/045401/article

Their main result is about 7m of SLR after one millennium under BAU. But they seem to use pretty conservative assumptions, such as a low model climate sensitivity. In an alternative analysis with somewhat less conservative assumptions, such as a climate sensitivy of 4 degrees C, they seem to find a potential SLR of about 26m by the year 3000. See in particular their figure 7:
http://iopscience.iop.org/1748-9326/7/4/045401/downloadFigure/figure/erl440214fig7

The models may indeed have problems getting the heat to the ice and/or the ice to the heat. They may already be good enough for the longer paleo-timescales, but it would be understandable if they're not up to date with the current unprecedented climate forcing yet. And if all or many other climate models are also too conservative still, then current process based model results for future SLR may very well be underestimates, right?

Maybe the semi-empirical models are more accurate in their projections, such as Meehl et al 2012, even if they lack the underlying physical processes. Or maybe they could also still be under-estimates?

As Meehl et al said: we may simply don't know. So that implies more risk rather then less, it seems.

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #188 on: November 09, 2014, 12:54:38 AM »
As Jai pointed out above, IPCC may also be conservative on carbon cycle feedbacks:
http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter06_FINAL.pdf

For example, they give 250 GtC by 2100 as a maximum (95% likelihood?) for carbon feedback from permafrost, but do mention that McDougal et al found a potential feedback of up to 500 GtC by 2100. Maybe McDougal et al are wrong, but what if they're right?

And they also seem not entirely clear on the methane feedback either, as they mention a potential extra 100 GtC feedback from methane, so 350 GtC in total, but the 250 GtC gets more emphasis than the 350 number. Or do I misunderstand?

jai mitchell

  • ASIF Upper Class
  • Posts: 1950
    • View Profile
  • Liked: 31
  • Likes Given: 7
Re: Conservative Scientists & its Consequences
« Reply #189 on: November 09, 2014, 02:06:38 AM »
Lennart,

you can download the different RCP scenarios' abundance, emissions and forcing data here:  http://www.pik-potsdam.de/~mmalte/rcps/index.htm#Download

when you do you will see that they do not include  permafrost, clathrates or albedo changes after 2100, however, they do show c02 continuing to increase until 2160 so that is probably their carbon cycle estimate.   However, they do not include the loss of the amazon, boreal forest, boreal peat and Indonesian forest/peat.  Their carbon cycle feedback under this scenario is grossly underestimated.  There is currently 2,000 PG of carbon in permafrost and boreal peat alone.  Under this scenario, all of it is released to the atmosphere.

I should state here that this worst case scenario is predicated on an ECS of 4.5 or higher.  I believe that this is what we will find to be the reality of our very dire situation as we have already well exceeded the 2C threshold under PPMV of 400 co2.

under the scenario that I pose, a runaway effect leads to a hothouse climate and a total cessation of the thermohaline current.  This will cause significantly increased temperature/depth profile gradients (in the northern latitudes and a smaller gradient in the tropics).  This will lead to a significant shift of heat deposition away from the  oceans and into the land/atmosphere at the tropics but lead to much greater OHC accumulation in higher latitudes.

The mechanics of ice sheet loss have been explained previously.  The ice sheet loss dynamics are not a function of radiative forcing under the RCP 8.5 scenario but rather are induced by significantly higher forcing coupled with precipitation and convection regime changes.   I think that the best analog to this kind of environment is the Larson B shelf disintegration due to melt pond formation and vertical shear stress.

you know, the original concept of shelf collapse.  This will occur on a level that is not analogous to any paleoclimate scenario that we have access to, and it is not modeled that I have found.

basically, take this run, add methane clathrates, reduce thermohaline cooling mechanisms.  massively increase co2 from multiple peat and forest zones that will be lost, decrease albedo in Antarctica to .3 and the arctic to .1 as well as significant volumes of hydrogen sulfide which has very high far infrared absorption spectrum http://webbook.nist.gov/cgi/cbook.cgi?ID=C7783064&Mask=80#IR-Spec  and we get what I am talking about.

« Last Edit: November 09, 2014, 07:31:49 AM by jai mitchell »
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

jai mitchell

  • ASIF Upper Class
  • Posts: 1950
    • View Profile
  • Liked: 31
  • Likes Given: 7
Re: Conservative Scientists & its Consequences
« Reply #190 on: November 09, 2014, 06:52:06 AM »
As Jai pointed out above, IPCC may also be conservative on carbon cycle feedbacks:
http://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_Chapter06_FINAL.pdf

For example, they give 250 GtC by 2100 as a maximum (95% likelihood?) for carbon feedback from permafrost, but do mention that McDougal et al found a potential feedback of up to 500 GtC by 2100. Maybe McDougal et al are wrong, but what if they're right?

And they also seem not entirely clear on the methane feedback either, as they mention a potential extra 100 GtC feedback from methane, so 350 GtC in total, but the 250 GtC gets more emphasis than the 350 number. Or do I misunderstand?

you didn't read the following sentence. . .

Quote
The CMIP5 Earth System Models did not include
frozen carbon feedbacks.

in other words they are saying, "yes, we have 90% probability in our current consensus understanding that the carbon from frozen sources will be 50-250PG by 2100, but we are not including that in our models.
Haiku of Past Futures
My "burning embers"
are not tri-color bar graphs
+3C today

Lennart van der Linde

  • ASIF Middle Class
  • Posts: 722
    • View Profile
  • Liked: 8
  • Likes Given: 1
Re: Conservative Scientists & its Consequences
« Reply #191 on: November 09, 2014, 12:58:29 PM »
Quote
they are saying, "yes, we have 90% probability in our current consensus understanding that the carbon from frozen sources will be 50-250PG by 2100, but we are not including that in our models

Yes, I thought that much was clear. But how about the estimated potential 5 GtC methane feedback, that could add another 100 GtC CO2e by 2100, beyond the 50-250 GtC mentioned above?

Quote
this worst case scenario is predicated on an ECS of 4.5 or higher

Ok, so are there any studies/models that show what could happen with an ECS of 4.5 or higher?

You refer to the PIK-site and essentially Meinshauen et al 2011:
http://edoc.gfz-potsdam.de/pik/get/5095/0/0ce498a63b150282a29b729de9615698/5095.pdf

Their figure 6 shows 8 degrees C by 2300 as their best estimate for RCP.8.5 with ECS 3 degrees.

But the range with other models included is much wider. I'm wondering if that range includes models with ECS of 4.5 or higher. And it's not clear to me how high their range reaches for 2200 and 2300. Is that the same as the figure you showed above, with about 10 degrees max in 2200, and a little over 12 degrees max by 2300? Or is this range only with ECS of 3 degrees?

Also they don't seem to talk specifically about permafrost feedbacks, but following IPCC they seem to be excluded. So how do we know what inclusion of the missing feedbacks you mention would mean for potential warming by 2200 and 2300?

You seem to assume it would or could cause 16 degrees warming by 2200, but is that a guess or based on some other studies not referred to yet? Or have I missed it being mentioned in earlier references?

GeoffBeacon

  • ASIF Citizen
  • Posts: 371
    • View Profile
  • Liked: 3
  • Likes Given: 4
Re: Conservative Scientists & its Consequences
« Reply #192 on: November 09, 2014, 01:16:24 PM »
Just back from a week away and enlightened but depressed by this thread.

Challenging the BBC

I'm making slow progress on classifying climate scientists to check the view that the BBC are avoiding the serious debate between “activist” scientists and  “official” ones but I've attended a couple of meetings this week where the “remaining carbon budget” was addressed.

The remaining carbon budget was taken to be the greenhouse gasses (or just CO2?) that can be emitted before we hit the 2 deg C “dangerous level” of global warming. 

The first meeting was the UK All Party Parliamentary Climate Change Group which included speakers from UK Sustainable Investment and Finance Association (http://uksif.org) who were addressing the dangers to economic stability if the corporations holding carbon assets cannot realise them because of restrictions on carbon emissions. None of the panellists challenged my assertion that these budgets were calculated using underpowered climate models so were too generous.

The second meeting included a speech from an MEP that Rajendra Pachauri, chair of the IPCC, had appeared before the European Parliament and said that we had used 65% of the allowable carbon budget.

I think the carbon budget idea far too simplistic – there are feedback effects not accounted for in  the budget - and does a 2 deg C over pre-industrial keep below a dangerous climate change threshold?  But carbon budget is a popular concept because it is easy for policy makers to use in the context of energy use for things like heat, power and transportation.

It has occurred to me that this idea would be a useful parameter in classifying opinions among climate scientists and climate commentators.  i.e. Ask them “What is the size of the carbon budget that can be omitted before triggering dangerous climate change?”

Should I try to contact relevant scientists and commentators to help create a league table with the initial aim of challenging the BBC's coverage? My crudely guessed league table is below with the mentions of the candidates that have appeared on the BBC website in the past year. I do admit the counting needs much more sophistication. Advice/help very much appreciated - even "don't bother" advice.

The classifications below are my guesses. This is the state-of-play so far. I set the Google searches to be for the past year only.

Climate scientists and climate commentator searches.

Activist 3 results

"Michael Mann" climate site:bbc.co.uk 2
"Kevin Anderson" climate site:bbc.co.uk 0
"James Hansen" climate site:bbc.co.uk 1
"Robert Watson" climate site:bbc.co.uk 0
"Peter Wadhams" climate site:bbc.co.uk 0
“Jason Box” climate site:bbc.co.uk 0
“Bill McKibben” climate site:bbc.co.uk 0
“Stefan Rahmstorf” climate site:bbc.co.uk 0
“Andrew MacDougall ” climate site:bbc.co.uk 0

Concerned 15 results

"Peter Cox" climate site:bbc.co.uk 2
"Jim Skea" climate site:bbc.co.uk 7
"David Mackay" climate site:bbc.co.uk 1
"Corinne Le Quere" climate site:bbc.co.uk 2
"Mike Lockwood" climate site:bbc.co.uk 3

Official 71 results

"Lord Stern" climate site:bbc.co.uk 13
"Julia Slingo" climate site:bbc.co.uk 10
"Myles Allen" climate site:bbc.co.uk 9
"Brian Hoskins" climate site:bbc.co.uk 8
"Mark Walpert" climate site:bbc.co.uk 9
"Rajendra Pasharui" climate site:bbc.co.uk 22

Skeptic 5 results

"Richard Tol" climate site:bbc.co.uk 2
"Piers Forster" climate site:bbc.co.uk 4
"Richard Lindzen" climate site:bbc.co.uk 1

« Last Edit: November 09, 2014, 01:30:43 PM by GeoffBeacon »
Il faut cultiver notre cité-jardin
The Sustainable Plotlands Association

crandles

  • ASIF Upper Class
  • Posts: 2125
    • View Profile
  • Liked: 25
  • Likes Given: 26
Re: Conservative Scientists & its Consequences
« Reply #193 on: November 09, 2014, 03:15:32 PM »
It has occurred to me that this idea would be a useful parameter in classifying opinions among climate scientists and climate commentators.  i.e. Ask them “What is the size of the carbon budget that can be omitted before triggering dangerous climate change?”

Do you think you would get different answers to AR5 high confidence answers:

Quote
Mitigation scenarios in which it is likely that the temperature change caused by anthropogenic GHG emissions can be kept to less than 2 °C relative to pre-industrial levels are characterized by atmospheric concentrations in 2100 of about 450 ppm CO2eq (high confidence). Mitigation scenarios reaching concentration levels of about 500 ppm CO2eq by 2100 are more likely than not to limit temperature change to less than 2 °C relative to pre-industrial levels, unless they temporarily ‘overshoot’ concentration levels of roughly 530 ppm CO2eq before 2100, in which case they are about as likely as not to achieve that goal.15 Scenarios that reach 530 to 650 ppm CO2eq concentrations by 2100 are more unlikely than likely to keep temperature change below 2 °C relative to pre-industrial levels. Scenarios that exceed about 650 ppm CO2eq by 2100 are unlikely to limit temperature change to below 2 °C relative to pre-industrial levels. Mitigation scenarios in which temperature increase is more likely than not to be less than 1.5 °C relative to pre-industrial levels by 2100 are characterized by concentrations in 2100 of below 430 ppm CO2eq. Temperature
peaks during the century and then declines in these scenarios. Probability statements regarding other levels of temperature change can be made with reference to Table SPM.1. [6.3, Box TS.6]
14
from WG III SPM

GeoffBeacon

  • ASIF Citizen
  • Posts: 371
    • View Profile
  • Liked: 3
  • Likes Given: 4
Re: Conservative Scientists & its Consequences
« Reply #194 on: November 09, 2014, 03:33:32 PM »
Crandles

Quote
The IPCC estimates that with cumulative emissions of 1000 GtC, there is a two-thirds chance of staying below 2°C relative to pre-industrial.
http://www.metoffice.gov.uk/research/news/gcb-2013

Do acknowledge that the CMIP5 models used for AR5 were underpowered because of missing feedbacks?

Is 2 deg C the threshold for "dangerous climate change"?

I know there are limitations to "remaining carbon budget" but that's easier for policy makers than "ppm"s. Is it possible to translate?
Il faut cultiver notre cité-jardin
The Sustainable Plotlands Association

TeaPotty

  • ASIF Citizen
  • Posts: 167
    • View Profile
  • Liked: 4
  • Likes Given: 0
Re: Conservative Scientists & its Consequences
« Reply #195 on: November 09, 2014, 04:47:56 PM »
Crandles

Quote
The IPCC estimates that with cumulative emissions of 1000 GtC, there is a two-thirds chance of staying below 2°C relative to pre-industrial.
http://www.metoffice.gov.uk/research/news/gcb-2013

Do acknowledge that the CMIP5 models used for AR5 were underpowered because of missing feedbacks?

Is 2 deg C the threshold for "dangerous climate change"?

I know there are limitations to "remaining carbon budget" but that's easier for policy makers than "ppm"s. Is it possible to translate?

Very well put.

When you look at the data and Climate Science as we understand it now, then its clear that the IPCC is essentially selling away our future. The carbon budget is understood by our politicians as an opportunity, a commodity with value they intend to profit from. Who in their right mind approved a budget with only a 66% success chance (not to mention all the other underestimations, omissions, dismissals, and even political meddling)?

Yes, there are many scientists speaking out, some mentioned here, others we may never know their name. But I see that the institutional powers of mainstream Science seem to be dominated by Conservatives, whose ideology essentially prevents them from making a good macro assessment of out situation.

I also reject the notion that not being a Conservative means one is an alarmist, as even James Hansen was calls for many years. Scientists need to be realists, devoid of fantastical ideas like Objectivism and Individualism. Conservatism is the search a for moral justification for selfishness.
« Last Edit: November 09, 2014, 06:53:45 PM by TeaPotty »

crandles

  • ASIF Upper Class
  • Posts: 2125
    • View Profile
  • Liked: 25
  • Likes Given: 26
Re: Conservative Scientists & its Consequences
« Reply #196 on: November 09, 2014, 06:17:25 PM »
Crandles

Quote
The IPCC estimates that with cumulative emissions of 1000 GtC, there is a two-thirds chance of staying below 2°C relative to pre-industrial.
http://www.metoffice.gov.uk/research/news/gcb-2013

Do acknowledge that the CMIP5 models used for AR5 were underpowered because of missing feedbacks?

Is 2 deg C the threshold for "dangerous climate change"?

I know there are limitations to "remaining carbon budget" but that's easier for policy makers than "ppm"s. Is it possible to translate?

My understanding is that the CMIP5 models have prescribed GHG levels rather than emissions and a carbon cycle. Now you can take this to mean that carbon cycle feedbacks are not included or, possibly more appropriately, say that the carbon cycle feedbacks reduce the levels of emissions (and sequestrations) needed to reach the ghg levels set for

Do acknowledge that the CMIP5 models used for AR5 were underpowered because of missing feedbacks?

Is 2 deg C the threshold for "dangerous climate change"?

I know there are limitations to "remaining carbon budget" but that's easier for policy makers than "ppm"s. Is it possible to translate?

My understanding is that the models have prescribed GHG levels and not emissions levels and a carbon cycle. Now you can claim this means that carbon cycle feedbacks are not included. I prefer the alternative of saying the cc feedbacks reduce the level of emissions that will reach the ghg levels set for the models.

Much model development is going into adding a carbon cycle into the models. Maybe AR6 will change this approach?

2C seems to be the threshold for "dangerous climate change" that politicians seem to use. Perhaps climatologists answers might be different.

translate? translate what to what?

from politicians 'dangerous' to climatologists 'dangerous' might be difficult but might in some way be possible with a survey of climatologists views of what is dangerous.

from dangerous climate change to carbon budget remaining or 2C above pre-industrial to carbon budget remaining?

Well it would be an estimated remaining carbon budget that came out in either case.
 
I see the big unknown being the amount of sequestration we can do rather than problems in the translation causing too much difficulty.

.

Quote
When you look at the data and Climate Science as we understand it now, then its clear that the IPCC is essentially selling away our future. Do understand, the carbon budget is understood by our politicians as a commodity with value they intend to profit from. Who in their right mind approved a budget with only a 66% success chance (not to mention all the other underestimation issues)?

IPCC does not decide policy, so how can it 'sell away our future'? Surely it is the politicians that do decide on policy that are failing to act sufficiently given the clear warnings from the IPCC.


To me there does seem a stark difference between a remaining carbon budget of about 11 years of current activity to get to 500ppm CO2eq (maybe a little more if you allow temporary overshoot to 530 ppm CO2eq) and recent headlines saying fossil fuels must be phased out by 2100. So perhaps my simple translation into remaining carbon budget is not the norm?

crandles

  • ASIF Upper Class
  • Posts: 2125
    • View Profile
  • Liked: 25
  • Likes Given: 26
Re: Conservative Scientists & its Consequences
« Reply #197 on: November 09, 2014, 06:27:05 PM »
590 to 790 GtC would be about 20 years activity at current levels to get to 'likely' remain below 2C. Perhaps the current level of 478ppm CO2eq level I used to get ~11 years to 'more likely than not' level wasn't correct.

TeaPotty

  • ASIF Citizen
  • Posts: 167
    • View Profile
  • Liked: 4
  • Likes Given: 0
Re: Conservative Scientists & its Consequences
« Reply #198 on: November 09, 2014, 07:31:19 PM »
Quote
When you look at the data and Climate Science as we understand it now, then its clear that the IPCC is essentially selling away our future. Do understand, the carbon budget is understood by our politicians as a commodity with value they intend to profit from. Who in their right mind approved a budget with only a 66% success chance (not to mention all the other underestimation issues)?

IPCC does not decide policy, so how can it 'sell away our future'? Surely it is the politicians that do decide on policy that are failing to act sufficiently given the clear warnings from the IPCC.


You misunderstand. To us the budget is a countdown to catastrophe. But the whole notion of a "budget" to politicians means something meant to be spent, an opportunity to profit. So the IPCC since it's very inception has been used as a tool to twist the science, and delay action. Heck, many IPCC meetings even helped sell tons of fossil fuels. Along with all other mentioned issues in this thread, this essentially guarantees we will overshoot targets.

GeoffBeacon

  • ASIF Citizen
  • Posts: 371
    • View Profile
  • Liked: 3
  • Likes Given: 4
Re: Conservative Scientists & its Consequences
« Reply #199 on: November 09, 2014, 09:23:05 PM »
Crandles

Quote
Now you can claim this means that carbon cycle feedbacks are not included.
So did the UK Parliamentary Office of Science and Technology in January this year. (Risks from Climate Feedbacks - POST Note 454)
Quote
Compared to existing model estimates, it is likely that climate feedbacks will result in additional carbon in the atmosphere and additional warming. This is because the majority of poorly represented climate feedbacks are likely to be amplifying feedbacks. This additional atmospheric carbon from climate feedbacks could make it more difficult to avoid a greater than 2˚C rise in global temperatures without additional reductions in greenhouse gas emissions. The strength of many amplifying feedbacks is likely to increase with warming, which could increase the risk of the climate changing state (Box 3). Some commentators suggest the uncertainties in our knowledge of carbon cycle and physical feedbacks may mean the Earth will warm faster than models currently estimate.
http://www.parliament.uk/briefing-papers/POST-PN-454.pdf

Crandles
Quote
I prefer the alternative of saying the cc feedbacks reduce the level of emissions that will reach the ghg levels set for the models.
If you mean the level of allowable anthropogenic emissions is reduced, that's OK. I'd call "allowable anthropogenic emissions" the carbon budget. So including feedbacks will reduce "the carbon budget".

TeaPotty
I think I agree but more is necessary to address the BBC question.  But is my approach likely to help?
Il faut cultiver notre cité-jardin
The Sustainable Plotlands Association