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Messages - AbruptSLR

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1
The forum / Re: Forum Decorum
« on: November 06, 2018, 07:19:09 AM »
The ultimate scenario is 1478 members ignoring each other. ;) I managed to ignore the comment I posted and the thread ASLR mentioned above, without killfiles.

But I do think that threads that start with a clear condescending intent of shutting down discussions, should be moderated. AGW is no joke.

Edit; howto ignore myself; read my follow up comment below.

2
Science / Re: ECS is 2.5
« on: November 03, 2018, 10:53:43 PM »
https://www.nature.com/articles/s41586-018-0651-8

Quote
Abstract

The ocean is the main source of thermal inertia in the climate system1. During recent decades, ocean heat uptake has been quantified by using hydrographic temperature measurements and data from the Argo float program, which expanded its coverage after 20072,3. However, these estimates all use the same imperfect ocean dataset and share additional uncertainties resulting from sparse coverage, especially before 20074,5. Here we provide an independent estimate by using measurements of atmospheric oxygen (O2) and carbon dioxide (CO2)—levels of which increase as the ocean warms and releases gases—as a whole-ocean thermometer. We show that the ocean gained 1.33 ± 0.20  × 1022 joules of heat per year between 1991 and 2016, equivalent to a planetary energy imbalance of 0.83 ± 0.11 watts per square metre of Earth’s surface. We also find that the ocean-warming effect that led to the outgassing of O2 and CO2 can be isolated from the direct effects of anthropogenic emissions and CO2 sinks. Our result—which relies on high-precision O2 measurements dating back to 19916—suggests that ocean warming is at the high end of previous estimates, with implications for policy-relevant measurements of the Earth response to climate change, such as climate sensitivity to greenhouse gases7 and the thermal component of sea-level rise8

your forcing parameters are AFU.

3
Consequences / Re: Global Surface Air Temperatures
« on: November 01, 2018, 03:49:25 AM »
Maybe not on topic on this thread. But here, anyway:
Oceans 'soaking up more heat than estimated'

https://www.bbc.com/news/science-environment-46046067

Quote
Researchers say that the world has seriously underestimated the amount of heat soaked up by our oceans over the past 25 years.

Their study suggests that the seas have absorbed 60% more than previously thought.

They say it means the Earth is more sensitive to fossil fuel emissions than estimated.

4
As continued global warming should increase the frequency with which atmospheric rivers reach Greenland, we may be in for some rude surprises in the coming decades (w.r.t. increasing rates of ice mass loss from the Greenland Ice Sheet):

William Neff (2018), "Atmospheric rivers melt Greenland", Nature Climate Change 8, 857-858, DOI: https://doi.org/10.1038/s41558-018-0297-4

http://www.nature.com/articles/s41558-018-0297-4

Abstract: "Recent years have seen increased melting of the Greenland Ice Sheet, contributing to accelerated rates of sea-level rise.  New research suggests that this melting due to an increased frequency of atmospheric rivers, narrow filaments of moist air moving polewards."

It worries me that we have this huge gravitationally unstable mass of ice on top of Greenland that is gradually warming, getting wet and having more snow piled on top of it, causing more pressure melting at it's base. The only thing keeping it up is the friction along it's base and its mechanical integrity. Once it loses mechanical integrity all bets are off. Whats to stop the whole damn thing sliding into the ocean in chunks?

An underlying principle in geology is that "The present is the key to the past". Unfortunately that doesn't really help us understand events that might happen once every 100,000 years.

5
Permafrost / Re: Arctic Methane Release
« on: September 25, 2018, 01:47:21 AM »
This Hissing, Bubbling Alaska Lake is Frightening Scientists
https://www.adn.com/arctic/2018/09/24/across-the-arctic-lakes-are-leaking-dangerous-greenhouse-gases/



ABOVE THE ARCTIC CIRCLE, ALASKA - Katey Walter Anthony has studied some 300 lakes across the tundras of the Arctic. But sitting on the mucky shore of her latest discovery, the Arctic expert said she’d never seen a lake like this one.

The first time Walter Anthony saw Esieh Lake, she was afraid it might explode - and she is no stranger to the danger, or the theatrics, of methane.

At first, the sheer volume of gases at Esieh Lake was slightly terrifying, but as Walter Anthony grew accustomed to the lake's constant spluttering, her fear gave way to wonder.

Her sounding devices picked up huge holes in the bottom of the lake. Pockmarks, she called them, “unlike anything I’ve ever seen in any Arctic lake.”

Most of Esieh is quite shallow, averaging only a little over three feet deep. But where the gas bubbles cluster, the floor drops suddenly, a plunge marked by the vanishing of all visible plant life.

Measurements showed that the lake dips to about 50 feet deep in one area and nearly 15 feet in another. When they first studied them, Walter Anthony and her graduate student Janelle Sharp named these two seep clusters W1 and W2, short for "Wow 1" and "Wow 2."

The next discovery came from the lab. ...

6
Permafrost / Re: Arctic Methane Release
« on: September 18, 2018, 07:56:33 PM »
Storegga submarine landslides may be more common than originally thought.

Scientists Closing In On Source of Shetland Tsunamis
Quote


Shetland Island (north of Scotland) has been hit by at least two more tsunamis in the past 10,000 years than previously thought, and scientists are working to identify where the giant waves originated.

Around 8,200 years ago, the Storegga  off the coast of Norway caused a 20m-high tsunami to sweep across Shetland. Sands found at various points across the isles, and in mainland Scotland, Norway, the Faroe Islands and Greenland, proved the tsunami's towering height, and the event has been well-reported.

Scientists funded by NERC have identified sands on Shetland that they say prove additional tsunamis hit Shetland 5,000 and 1,500 years ago. This could mean that tsunamis are a more common occurrence than previously thought in the UK.
Quote
... We found sands aged 5,000 and 1,500 years old at multiple locations in Shetland, up to 13 meters (42 feet) above sea level. These deposits have a similar sediment character as the Storegga event and can therefore be linked to tsunami inundation.
... Submarine landslides can occur on slopes of just one or two degrees, and we still don't know exactly how they are set in motion, except that earthquakes are considered to be the most common trigger. It is critical that we learn more.

The research is part of the Landslide-Tsunami project, ongoing research that forms a key element of NERC's Arctic Research Programme. The project aims to discover what causes enormous submarine landslides, what the impact of slides in different locations and of different magnitude would be on the UK, and what the likelihood of such an event might be, given the significant scale of Arctic climate change.


https://nerc.ukri.org/planetearth/stories/1906/

7
Consequences / Re: Conservative Scientists & its Consequences
« on: July 05, 2018, 09:51:19 PM »
https://newsroom.unsw.edu.au/news/science-tech/global-warming-may-be-twice-what-climate-models-predict

Global warming may be twice what climate models predict

A new study based on evidence from past warm periods suggests global warming may be double what is forecast.

Quote
The findings published last week in Nature Geoscience are based on observational evidence from three warm periods over the past 3.5 million years when the world was 0.5°C-2°C warmer than the pre-industrial temperatures of the 19th Century.

The research also revealed how large areas of the polar ice caps could collapse and significant changes to ecosystems could see the Sahara Desert become green and the edges of tropical forests turn into fire dominated savanna.

“Observations of past warming periods suggest that a number of amplifying mechanisms, which are poorly represented in climate models, increase long-term warming beyond climate model projections,” said lead author, Prof Hubertus Fischer of the University of Bern.

Paper here:  https://www.nature.com/articles/s41561-018-0146-0

Palaeoclimate constraints on the impact of 2 °C anthropogenic warming and beyond

Abstract: 

Over the past 3.5 million years, there have been several intervals when climate conditions were warmer than during the pre-industrial Holocene. Although past intervals of warming were forced differently than future anthropogenic change, such periods can provide insights into potential future climate impacts and ecosystem feedbacks, especially over centennial-to-millennial timescales that are often not covered by climate model simulations. Our observation-based synthesis of the understanding of past intervals with temperatures within the range of projected future warming suggests that there is a low risk of runaway greenhouse gas feedbacks for global warming of no more than 2 °C. However, substantial regional environmental impacts can occur. A global average warming of 1–2 °C with strong polar amplification has, in the past, been accompanied by significant shifts in climate zones and the spatial distribution of land and ocean ecosystems. Sustained warming at this level has also led to substantial reductions of the Greenland and Antarctic ice sheets, with sea-level increases of at least several metres on millennial timescales. Comparison of palaeo observations with climate model results suggests that, due to the lack of certain feedback processes, model-based climate projections may underestimate long-term warming in response to future radiative forcing by as much as a factor of two, and thus may also underestimate centennial-to-millennial-scale sea-level rise.

8
Consequences / Re: Conservative Scientists & its Consequences
« on: June 29, 2018, 05:58:23 PM »
https://t.co/1w3U1O2ivK

Palaeoclimate constraints on the impact of 2 °C anthropogenic warming and beyond

This paper uses new constraints on long-term impacts to the earth's system under much warmer paleoclimate regimes.  It indicates that current models used are vastly underestimating historic Arctic Amplification and that some land-ice feedbacks not included in the models due to their perceived timeline of impact should be included as these feedbacks are much more rapid than modeled. 

Using their model and adjusting for current conditions (reduced land ice as we are in an interglacial) they find that the ECS for 2XCO2 is closer to 7C than 3C.



Quote
The EECO simulations that include the effect of surface albedo (blue triangles) are closer to the palaeo reconstructions, but still underestimate the inferred EECO warming at high CO2

9
Consequences / Re: Conservative Scientists & its Consequences
« on: June 07, 2018, 07:06:47 PM »
Cross Posted from Aerosols thread.

------------
Earlier papers that project aerosol forcing have real problems since many (most!) of the ESM models did not include key (known) atmospheric and atmospheric chemistry interactions with aerosols.  These models underestimate the aerosol effect.  This has been well known even before the publication of AR5 as satellite observations indicated much greater effects than were being modeled.

This total indirect effect is comprised of First (FIE) and Second (SIE) indirect effects, both are negative (cooling). 

The lack of these mechanisms in some models and the poor representation (compared to direct observations in others) led to the great uncertainty bars in the AR4 and AR5 (image below) for this effect.  The total indirect effect here is labeled "Cloud Adjustments due to Aerosols" with a median value of about 0.56 Watts/m^2.

Recent observations from the Satellite record indicate that the FIE component itself is underestimated by approximately 23% which has a cascading local effect based on relative humidity of several watts per meter squared.  See: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL077679

Quote
One‐unit enhancement in aerosol scattering coefficient by swelling effect is found to lead to a systematic underestimation of the first indirect effect (FIE) by about 23% that can result in an underestimation in the FIE‐related radiative forcing by several W/m2 depending on aerosol properties and relative humidity.

Recent observations from the satellite record performed by a different team of scientists shows that the FIE effect is approximately double the total effect shown in the graphic below (and cited as the median value of aerosol cloud impacts in AR5) See : http://www-k12.atmos.washington.edu/~dennis/McCoy-2017-Theglobalaerosol-cloud.pdf

Quote
Using preindustrial emissions models, the change in Nd between preindustrial and present day is estimated. Nd is inferred to have more than tripled in some regions. Cloud properties from Moderate Resolution Imaging Spectroradiometer (MODIS) are used to estimate the radiative forcing due to this change in Nd. The Twomey (FIE) effect operating in isolation is estimated to create a radiative forcing of -0.97 ± 0.23 W m^2 relative to the preindustrial era.

The problem (and this will be cross posted in the "Conservative Scientists" thread) is that these more recent papers that rely on models specifically tuned to include the total effects of aerosols show much higher cooling impacts, especially in the  Arctic than your examples.  see: https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GL076079

Quote
We note that in two models, Arctic warming due to aerosol reductions reaches 4°C in some locations (Figures S2–S5). The four‐model mean increase for the 60°N–90°N region is 2.8°C.

note:  Even the four models used in this paper severely underestimate the FIE as shown in the first papers (23%) cited which was published only 1 month ago

Image of average model (4 model) response to aerosols removal found here: https://wol-prod-cdn.literatumonline.com/cms/attachment/46814f2f-f617-4dea-83ce-0ab4c61244bf/grl56865-fig-0002-m.jpg

You can download the Supplementary information with the individual model results of aerosol removal on temperatures (figures S2-S5) here:
https://agupubs.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1002%2F2017GL076079&attachmentId=2186427861

It is strongly urged that you limit your research for best accuracy to papers less than 2 years old since the modeling capabilities have increased significantly since 2015.  I understand that this has produced a lot of confusion in the discussion since the understanding of these aerosol impacts are changing very rapidly.

10
Consequences / Re: 2018 ENSO
« on: June 01, 2018, 03:13:31 PM »
SOI calculations differ Buddy. And the SOI can dive down and then jump up again over several months and years. This is the formula that Long Paddock uses:

They use 1887-1989 as base period (std dev diff) and 10 as a multiplier.
BoM (which ASLR regularly posts values from) also use 10, but 1933-1992 as base period which is probably better, I believe some of the olders values are a bit shaky. Others use a different base period and/or a different multiplier. Then you also have the equatorial SOI.

To be able to say anything about where ENSO is going, one must also look at SST, SLP, wind and OLR indices. One can't really say anything just looking at the SOI. You need the team to play ball.
Add subsurface temps and equatorial kelvin waves, etc.

11
Science / Re: AMOC slowdown
« on: May 30, 2018, 02:33:46 PM »
In the response he indicated that melt has impact on surface salinity but not on largescale temperature.

"[Response: You mean by cold meltwater from Greenland flowing in? You can work that out from a simple heat budget calculation. The amount is far too small to matter for the large-scale sea surface temperature, but enough to matter for sea surface salinity. -Stefan] "

I did a simple heat calculation, and i agree with him.

sidd

Stefan's being a little disingenuous here. It makes a big difference to the cooling whether the ice melts on shore and meltwater enters the sea, or whether icebergs fall off Greenland and the ice melts at sea. Hansen reckoned that cooling was important enough to hose with a berg/meltwater mix rather than the traditional meltwater only, and I'm inclined to accept his judgement on it.


12
Consequences / Re: Conservative Scientists & its Consequences
« on: May 09, 2018, 09:42:47 PM »
Re: Cloud Forcing in models

See also:  https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/2018GL077904

Quote
To the extent that the physics of the local positive SST-LCC feedback inferred from observed climate variability applies to future greenhouse warming, we anticipate significant amount of delayed warming because of SST-LCC feedback when anthropogenic SST warming eventually overwhelm the effects of internal variability that may mute anthropogenic warming over parts of the ocean. We postulate that many climate models may be underestimating both future warming and the magnitude of modeled internal variability because of their weak SST-LCC feedback.

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