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Messages - AbruptSLR

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1
Thanks for this excellent summary of upside risks to Thwaites glacier, ASLR. And for your ongoing posting here - much obliged. Happy trails as you travel...

2
Perhaps the largest obstruction blocking societies willingness/ability to face the true risks of abrupt climate change (likely to be triggered by ice-climate feedback mechanisms not adequately addressed by consensus climate science reports), can be characterized by what Sir Francis Bacon described as the 'four idols' of the mind (see the first linked article).  <snip>

Hello ASIForum members, especially AbruptSLR!! I've registered on the forum and logged in for the express purpose of leaving this reply. Note, however, I've been following multiple threads, daily, here for nearly a decade. Also, I apologize in advance that this comment will stray slightly off-topic.

Thank you, ASLR, for that comment about Sir Francis Bacon and his "4 Idols" theory. His observations mesh closely with my own over the past 50+ years. However, I refer to the "obstructions" simply as "beliefs." Too many people, the world over, proclaim to believe many things. Often, those beliefs are contradictory to others claimed to be held and, more significantly, most people act antithetically to the beliefs they claim to hold. I'm sure most, if not all, of the beliefs people hold can be categorized into one or more of Bacon's "4 Idols," and they are the most critical factors of all impeding "progress" of any kind, not least of which being the continuing existence of the human species.

I thank you, ASLR, ad infinitum, for your continued work and comments in this forum, though I do miss your erudition in other threads but understand and accept your reasoning behind that decision. Please, keep up the good work, your words and supplied links generally "make my day."

I would add to this all sorts of presuppositions which are not consciously held beliefs, but which are built into our practices, including our ways of talking (and so of thinking).

Or as the 20th century philosopher Ludwig Wittgenstein put it:

Quote
94. But I did not get my picture of the world by satisfying myself of its correctness; nor do I have it because I am satisfied of its correctness. No: it is the inherited background against which I distinguish between true and false.

95. The propositions describing this world-picture might be part of a kind of mythology. And their
role is like that of rules of a game; and the game can be learned purely practically, without learning any explicit rules.

96. It might be imagined that some propositions, of the form of empirical propositions, were
hardened and functioned as channels for such empirical propositions as were not hardened but fluid; and that this relation altered with time, in that fluid propositions hardened, and hard ones became fluid.

97. The mythology may change back into a state of flux, the river-bed of thoughts may shift. But I distinguish between the movement of the waters on the river-bed and the shift of the bed itself;
though there is not a sharp division of the one from the other.

98. But if someone were to say "So logic too is an empirical science" he would be wrong. Yet this is right: the same proposition may get treated at one time as something to test by experience, at
another as a rule of testing.

99. And the bank of that river consists partly of hard rock, subject to no alteration or only to an
imperceptible one, partly of sand, which now in one place now in another gets washed away, or
deposited.

The difficult thing is that this applies to all of us. We can never think outside of language, and language always contains mythologies. Or as Slavoj Zizek puts it "unknown knowns."


3
Perhaps the largest obstruction blocking societies willingness/ability to face the true risks of abrupt climate change (likely to be triggered by ice-climate feedback mechanisms not adequately addressed by consensus climate science reports), can be characterized by what Sir Francis Bacon described as the 'four idols' of the mind (see the first linked article).  <snip>

Hello ASIForum members, especially AbruptSLR!! I've registered on the forum and logged in for the express purpose of leaving this reply. Note, however, I've been following multiple threads, daily, here for nearly a decade. Also, I apologize in advance that this comment will stray slightly off-topic.

Thank you, ASLR, for that comment about Sir Francis Bacon and his "4 Idols" theory. His observations mesh closely with my own over the past 50+ years. However, I refer to the "obstructions" simply as "beliefs." Too many people, the world over, proclaim to believe many things. Often, those beliefs are contradictory to others claimed to be held and, more significantly, most people act antithetically to the beliefs they claim to hold. I'm sure most, if not all, of the beliefs people hold can be categorized into one or more of Bacon's "4 Idols," and they are the most critical factors of all impeding "progress" of any kind, not least of which being the continuing existence of the human species.

I thank you, ASLR, ad infinitum, for your continued work and comments in this forum, though I do miss your erudition in other threads but understand and accept your reasoning behind that decision. Please, keep up the good work, your words and supplied links generally "make my day."

4
Abrupt, Any slowdown on the MOC would also reduce the ocean carbon sink. The North Atlantic down welling area sends vast amounts of organic matter and carbonates into the deep ocean where they remain until upwelling brings DIC ( dissolved inorganic carbon ) back into atmospheric contact , a cycle lasting hundreds of years to more than a thousand years .A slowdown with down welling in the Southern end of the MOC and would also result in a reduction in the ocean carbon sink.




5
Jai, Just the opinion of a farmer, the terrestrial carbon sink is dependent upon plants and trees to go through an annual growth cycle. With adequate soil moisture plants grow roots and contribute to soil humus buildup. With drying conditions there is less organic matter and carbon sequestration so the terrestrial carbon sink goes into decline and the carbon in the soil oxidizes and goes back into the atmospheric carbon sink , increasing ECS. Also forest health declines , there is more insect damage and more fires.

6
what is the mechanism for soil drying to lead to increased ECS? 

7
This may be of some use

Quote
August 2011. Regions with predominant FYI show larger heat input than those with predominating MYI, but the absolute flux is also controlled by surface solar irradiance. Including fluxes through open water, the effect of sea‐ice concentration (Figure S4) becomes most obvious, particularly in the marginal ice zones, and fluxes within the sea‐ice extent reach more than 5 W m−2 (Figure S6). Mean heat flux through the sea ice over the entire Arctic was 0.68 W m−2(mean transmittance: 0.08) in August 2011. Including open water within the sea‐ice extent it was 12.3 W m−2 (mean transmittance: 0.40)



https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL053738#support-information-section

Changes in Arctic sea ice result in increasing light transmittance and absorption

Our results show that transmittance through first‐year ice (FYI, 0.11) was almost three times larger than through multi‐year ice (MYI, 0.04), and that this is mostly caused by the larger melt‐pond coverage of FYI (42 vs. 23%). Also energy absorption was 50% larger in FYI than in MYI. Thus, a continuation of the observed sea‐ice changes will increase the amount of light penetrating into the Arctic Ocean, enhancing sea‐ice melt and affecting sea‐ice and upper‐ocean ecosystems.

8
Quote
papers that might indicate why the Lincoln Sea/Nares is so late to freeze during recent years
These two article may offer some clues:
Nares Strait hydrography and salinity field from a 3‐year moored array
B. Rabe, A. Münchow, H. L. Johnson and H. Melling
First published: 17 July 2010  https://doi.org/10.1029/2009JC005966
extract from Abstract:
Quote
...
Data show warm salty water on the Greenland side and cold fresher water on the Ellesmere Island side, especially in the top layers. There was a clear difference in hydrographic structure between times when sea ice was drifting and when it was land fast. Ice was drifting in late summer, fall, and early winter with a strong surface‐intensified geostrophic flow in the middle of the strait. Ice was land fast in late winter, spring, and early summer, when there was a subsurface core of strong geostrophic flow adjacent to the western side of the strait. Salinity variations of about 2 psu in time and space reflect a variable freshwater outflow from the Arctic Ocean. One particularly strong pulse occurred at the end of July 2005. For several days, steeply sloping isohalines indicated strong geostrophic flow down the middle of the strait coinciding with an amplified ice export from the Arctic due to strong southward winds.

Water, Heat, and Salt Transports through Nares Strait, Ellesmere Island
H. Eric Sadler
Published on the web 14 April 2011 - Journal of the Fisheries Research Board of Canada

Abstract
Quote
Data obtained in Nares Strait are used to provide estimates of the transports of water, heat, and salt between the polar ocean and northern Baffin Bay. The annual volume export of water through Nares Strait is 2.1 × 104 km3 ± 30%, which is equivalent to a mean flow of 0.67 × 106 m3∙s−1 and which is about 15% of the total outflow of water from the polar ocean. The annual net heat input into the polar ocean due to the outflow of cold water and ice is found to be 15 × 1019 J ± 50% assuming a reference temperature of −0.1 C. This volume is about 7% of the total advective heat transport into the polar ocean. The mean annual export of salt from the polar ocean is 6.7 × 1014 kg ± 30% or about 6% of the total export. The total transports through the whole Canadian archipelago are estimated and it is shown that they are appreciable fractions of the total exchanges between the polar ocean and the world ocean.

9
Echoing the previous 2 comments, at risk of creating a "too long" off-topic comment chain.

These are the type of threads & information I come here for. I love it, thanks.

10
ASLR,

I just want to "join" Shared Humanity in saying that your contributions in this thread are very valuable and necessary. I thank you for your daily effort of informing us about the latest results of peer-reviewed science.

Stephan

11
For those who still do not understand how tropical oceanic energy, via evaporated water into the atmosphere, is telecommunicated (within weeks to months) poleward.......

Ooooh....me, me, me.....

SH,

Feel free to ask questions, as everyone knows that long-tail climate change is a complex and somewhat confusing topic.

ASLR

ASLR,

I rarely comment on these types of threads but want you to know I visit them daily. I suspect there are many others who do the same.

Thank you.

12
For those who still do not understand how tropical oceanic energy, via evaporated water into the atmosphere, is telecommunicated (within weeks to months) poleward.......

Ooooh....me, me, me.....

13
"...the degree to which aerosols cool the earth has been grossly underestimated..."

That sounds...rather bad!

14
The linked reference and associated image, indicate that observed Ocean Heat Content, OHC, has increased more rapidly than indicated by AR5.  Hopefully, AR6 will recognize that this trend is not good for mankind's future:

Lijing Cheng, John Abraham, Zeke Hausfather & Kevin E. Trenberth (11 Jan 2019), "How fast are the oceans warming?", Science, Vol. 363, Issue 6423, pp. 128-129, DOI: 10.1126/science.aav7619

They had Zeke Hausfather on The Real News!

Link >>

15
The Bevis paper is interesting. They use GIA as well as a bunch of other observations to estimate GIS mass waste. One  takeaway is that in the twentieth century, atmosphere had not warmed enuf for NAO variation to induce mass waste events thru increased SMB. But this century it is.

"Since 2000, the NAO has worked in concert with global warming to trigger major increases in summertime runoff. Before 2000, the air was too cool for the NAO to do the same. In a decade or two, global warming will be able to drive 2012 levels of runoff with little or no assistance from the NAO. In the shorter term, we can infer that the next time NAO turns strongly negative, SMB will trend strongly negative over west and especially southwest Greenland ..."


They also point out several interesting things. The pause after 2012 was due to NAO :

"Van Angelen et al. (13) concluded that if the sNAO switched back to positive values after 2012, then surface mass balance (SMB) might partially recover. Indeed, not only did the June to August (JJA) and June to September (JJAS) NAO indices turn positive in 2013, but the change in each of these sNAO indices from 2012 to 2013 was the single biggest interannual change recorded since 1950 (Fig. 1 F and G and SI Appendix, Fig. S7). Furthermore, when the sNAO index again turned strongly negative in 2015, significant ice loss was reestablished (Fig. 1 B and E), and the Pause had ended."

Another point they make is that glacier discharge is governed by shallow marine warmth:

"future warming of the shallow ocean is expected to have its largest impact, via DMB (33, 34), in southeast and northwest Greenland"

But the last is not the focus of the paper.

Open access, read all about it:

doi: 10.1073/pnas.1806562116

sidd

16
I always understood the total Greenland (or generally any) ice sheet mass change in a year to mainly be a result of the amount snowfall, melt and calving:
mass change = gain from snowfall - loss from melt - loss through calving
Is this correct?

https://climate.nasa.gov/vital-signs/ice-sheets/

The linked page contains a graph that has data until June 2017 and shows an ongoing downward trend in the Greenland total ice sheet mass.

Yes, the mass loss accelerated from 2003 up until 2012.  However, since then it has decelerated dramatically, to the point where it may actually be gained mass.

http://sciencenordic.com/how-greenland-ice-sheet-fared-2018

https://nsidc.org/greenland-today/

"Exceptional winter snow accumulation and heavy, summer snowfall, drove the net snow input mass to 130 billion tons above the 1981 to 2010 average. This was followed by a near-average melt and runoff period, resulting in a large net mass gain for the ice sheet in 2018 of 150 billion tons. This is the largest net gain from snowfall since 1996, and the highest snowfall since 1972. However, several major glaciers now flow significantly faster than in these earlier years. The net change in mass of the ice sheet overall, including this higher discharge of ice directly into the ocean, is not clear at this point but may be a smaller loss or even a small gain. This is similar to our assessment for 2017, and in sharp contrast to the conditions for the preceding decade."

Do I understand this analysis correctly that this downward trend could have been broken in 2017 and 2018? That would be great news.

17
Anyone got the doi for the Bevis paper on GIS ? i searched the PNAS site but it didnt appear for 2019

Re: Wolf: I think i agree with Wolf's results on CO2 at high concentrations increasing sensitivity. What I don't trust is the cloud albedo feedback bit.

sidd

Wouldn't a warmer planet cause the cloud albedo to lessen, due to there being more water vapor in the atmosphere, causing clouds to have more rain droplets, therefore making them darker. This isn't my field of study, but that makes sense to me

18
indeed the current rate of CO₂ emissions is somewhere to 10 to 15 time the rate during the PETM (depending on which part of the PETM we compare to add whether we consider CO₂-equiv emission rates)

Scanning several papers on the PETM again I see estimates on the rate of emissions and warming vary significantly, so it's hard to have much confidence in any particular estimate, whether it was 10x slower than currently, 100x slower, or maybe even as fast as currently.

As Turner 2018 concludes:
https://royalsocietypublishing.org/doi/full/10.1098/rsta.2017.0082

"After more than 25 years of intense study, the PETM continues to be the best analogue for future CO2-driven global warming. However, the aspect of the PETM that is most relevant for understanding future impacts—the duration of carbon release—is extremely challenging to constrain using the typical methods for determining age in the geologic record (biomagnetostratigraphy and cyclostratigraphy). Combined data and modelling studies offer a potential way forward by suggesting simulacra of the traces left in the geologic record that indicate a short carbon input duration. Each of the age-model independent methods outlined here has caveats in its application; however, a consensus appears to be emerging that the carbon emissions that drove the CIE occurred over just a few thousand years. This still suggests emissions rates about 10× slower than the current annual average, but is similar to predicted rates of additional carbon release from natural carbon cycle feedbacks..."

However, 10x slower emissions 56 million years ago when CO2 levels were higher to begin with and the sun was somewhat weaker than now implies CO2-forcing is currently already probably substantially more than 10x stronger than during the PETM, and rising fast as long as we don't eliminate our emissions. What that does to ECS humanity will find out in coming decades and centuries, assuming there will be humans around and they will still be able to determine ECS.

19
the current high rate of anthropogenic radiative forcing (at least 100 times faster than during the PETM)

This may well happen later this century, but currently it seems more like 10x faster than during the PETM, according to Diffenbaugh & Field 2013 (see attachments below):
http://denning.atmos.colostate.edu/readings/Impacts/Ecosystems.Science-2013-Diffenbaugh-486-92.pdf

Such fast warming may indeed cause ECS to increase to levels that are higher than the natural ECS at the same temperature in the past, as far as I know (I would have to look for specific references).

20
That Wolf paper has very little to do with present day earth, it has to do with mostly hypothetical climates, and hot ones at that. They use present day continents, fainter and brighter suns and they vary CO2 levels.

But

1) permanent land glaciers over Antarctica and Greenland have been replaced with bare soil

2) thermodynamic slab ocean model of 50‐m depth

3) We assume a 1‐bar N2 background ... we have ignored the formation of stratospheric ozone and the presence of oxygen in the atmosphere.

I attach Fig 1 and 6

To the question of a cloud albedo transitions:

"Similarly, here we find that the global mean cloud albedo varies in proportion with the solar insolation at all values of Ts (Figure 6b), and across a range of insolations. Under all solar constants cloud feedbacks have a destabilizing effect on climate for 280 ≤ Ts ≤ 330 K. That is, warming climate leads to reductions in the cloud albedo, thus constituting a positive climate feedback and leading to further warming. The sharp transition between temperate and moist greenhouse climate states centered at Ts ~320 K is associated with the minima in cloud albedo (Figure 6b), and is caused by the convective stabilization of warm atmospheres and subsequent dissipation of low‐lying clouds as reported in Wolf and Toon (2015)."

I dont really believe the accuracy of their cloud model. First off, their grid is 4x5 degrees in a modified CESM model, so they rely on parametrization for cloud effects. Their ocean is laughably simple. They have no biology. But as Box said, "all models are wrong but some are useful" This one is not very useful to me, i prefer Hansen and the Russel model he uses for simple, quick looks at the rape of things to come.

But, as always, thats just me, your mileage may vary
.
sidd



21
Anyone has access to the full text?

They're talking about quite warm climates:
https://sci-hub.tw/https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018JD029262

"ECS for the first three CO2 doublings beyond the present day Earth (up to 2880 μbar CO2) fall within the IPCC estimated range, with values of 3.8 K, 4.0 K, and 4.1 K respectively (gray box in Figure 1b). At the 4th CO2 doubling (5760 μbar CO2) ECS exceeds the IPCC estimated range, reaching 5.8 K. Thus, the sensitivity of climate accelerates under potential anthropogenic CO2 increases, in agreement with recent studies [Meraner et al., 2013; Russell et al., 2013; Caballero and Huber, 2013]. We find a sharp maximum in ECS of 16.0 K evident at the 6th CO2 doubling (0.02304 bar CO2) beyond present day Earth conditions... warming climate leads to reductions in the cloud albedo, thus constituting a positive climate feedback and leading to further warming. The sharp transition between temperate and moist greenhouse climate states centered at Ts ~ 320 K is associated with the minima in cloud albedo"

22
In the paper by Wolf et al they say in the Abstract, as quoted by ASLR:

"We also find that the cloud albedo feedback causes an abrupt transition in climate for warming atmospheres that depends both on the mean surface temperature and the total solar insolation."

As the paper is paywalled I remain in the dark about what this could possibly mean. Especially interesting would be to learn at what latitudes such abrupt transition might happen.
Anyone has access to the full text?

23
Hopefully, CMIP6 and future phases of E3SM, will improve upon the accuracy of our current projections.

Yes and the E3SM Equilibrium Climate Sensitivity of 5.3K is based on the dynamical sensitivity effects you linked below, including a split of the ITCZ, greatly decreasing albedo (among many other impacts).

The immediate following linked reference clarifies the relationship of ECS and the dynamical sensitivity of climate models.:

Kevin M. Grise & Lorenzo M. Polvani (28 April 2016), "Is climate sensitivity related to dynamical sensitivity?", Journal of Geophysical Research Atmospheres, DOI: 10.1002/2015JD024687


http://onlinelibrary.wiley.com/doi/10.1002/2015JD024687/abstract

Abstract: "The atmospheric response to increasing CO2 concentrations is often described in terms of the equilibrium climate sensitivity (ECS). Yet, the response to CO2 forcing in global climate models is not limited to an increase in global-mean surface temperature: for example, the mid-latitude jets shift poleward, the Hadley circulation expands, and the subtropical dry zones are altered. These changes, which are referred to here as “dynamical sensitivity,” may be more important in practice than the global-mean surface temperature.

This study examines to what degree the inter-model spread in the dynamical sensitivity of 23 CMIP5 models is captured by ECS. In the Southern Hemisphere, inter-model differences in the value of ECS explain ~60% of the inter-model variance in the annual-mean Hadley cell expansion, but just ~20% of the variance in the annual-mean mid-latitude jet response. In the Northern Hemisphere (NH), models with larger values of ECS significantly expand the Hadley circulation more during winter months, but contract the Hadley circulation more during summer months. Inter-model differences in ECS provide little significant information about the behavior of the Northern Hemisphere subtropical dry zones or mid-latitude jets.

The components of dynamical sensitivity correlated with ECS appear to be driven largely by increasing sea surface temperatures, whereas the components of dynamical sensitivity independent of ECS are related in part to changes in surface temperature gradients. These results suggest that efforts to narrow the spread in dynamical sensitivity across global climate models must also consider factors that are independent of global-mean surface temperature."

Finally, I provide the following reference related to the calibration of dynamical sensitivity of climate models using paleodata.


Wanted to share this one.

http://eprints.whiterose.ac.uk/132373/8/IMBIE2_accepted_v16.pdf
Mass balance of the Antarctic Ice Sheet from 1992 to 2017

Quote
Ocean-driven melting has caused rates of ice loss from West Antarctica to rise from 53 ± 29 Gt/yr in the 1990s to 159 ± 26 Gt/yr in the 2010s. Ice shelf collapse has driven Antarctic Peninsula ice loss up from 7 ± 13 Gt/yr in the 1990s to 33 ± 16 Gt/yr in the 2010s. We find large variations in and among model estimates of surface mass balance and glacial isostatic adjustment in East Antarctica, and its 25-year mass trend (5 ± 46 Gt/yr) is still the least certain.

24
ASLR...

Thank you for the Plain Language Summaries on your posts.

25
I wish I could :)

26
There is not yet a compelling theory for the magnetic field or magnetic polar wander. There is almost certainly a coupling between the location of the spin axis and the magnetic poles, but the nature of this coupling is not understood, probably because the nature of the magnetic field is not well understood. There is a Nobel waiting for anyone who comes up with answers.

Could small changes in the position of the spin axis maybe cause changes in convection in the outer core, and could those in turn cause (small) changes in the position of the magnetic pole, as one factor amongst others?

Here someone says:
http://all-geo.org/highlyallochthonous/2008/03/where-the-earths-magnetic-field-comes-from/
“Earth’s rotation… has a strong influence on the patterns of convection in the outer core. Most significantly, it has a tendency to produce helical convection currents which align with the spin axis…”.

The geographical pole apparently moves partly due to convection in the Earth mantle:
https://phys.org/news/2018-09-scientists-id-earth-axis-drift.html
“Using observational and model-based data spanning the entire 20th century, NASA scientists have for the first time identified three broadly-categorized processes responsible for this drift—contemporary mass loss primarily in Greenland, glacial rebound, and mantle convection... Mantle convection is responsible for the movement of tectonic plates on Earth’s surface. It is basically the circulation of material in the mantle caused by heat from Earth’s core. Ivins describes it as similar to a pot of soup placed on the stove. As the pot, or mantle, heats, the pieces of the soup begin to rise and fall, essentially forming a vertical circulation pattern—just like the rocks moving through Earth’s mantle.”

Or is this hypothesis too farfetched?

27
Whether the acceleration in magnetic polar wander shown in the first attached image (from Nature 2019) is related to the high magnetic anomaly in the South Atlantic, see the second image (and Replies #113, #115 & #117), and thus possibly to Antarctic ice mass loss, is a matter worth investigating.

Maybe this could contribute to an explanation:
http://advances.sciencemag.org/content/2/4/e1501693

“We analyze space geodetic and satellite gravimetric data for the period 2003–2015 to show that all of the main features of polar motion are explained by global-scale continent-ocean mass transport. The changes in terrestrial water storage (TWS) and global cryosphere together explain nearly the entire amplitude (83 ± 23%) and mean directional shift (within 5.9° ± 7.6°) of the observed motion. We also find that the TWS variability fully explains the decadal-like changes in polar motion observed during the study period, thus offering a clue to resolving the long-standing quest for determining the origins of decadal oscillations. This newly discovered link between polar motion and global-scale TWS variability has broad implications for the study of past and future climate.”

The Nature article doesn't seem to mention this possibility?

28
ASLR...you never cease to amaze me...I read much of what you post...learn every time I do but this piece is fascinating...

29
Thanks, ASLR, for introducing us (me) to "Markov blankets".  It helps explain why I still drive a Prius (even if it is 17 years old).  I like that these 'things' can be numericalized, but that is above my pay-grade.

30
More Glaciers in East Antarctica Are Waking Up https://www.nasa.gov/feature/goddard/2018/more-glaciers-in-antarctica-are-waking-up

Quote
East Antarctica has the potential to reshape coastlines around the world through sea level rise, but scientists have long considered it more stable than its neighbor, West Antarctica. Now, new detailed NASA maps of ice velocity and elevation show that a group of glaciers spanning one-eighth of East Antarctica’s coast have begun to lose ice over the past decade, hinting at widespread changes in the ocean.

31
I thought this was a rather good popular press article about Thwaites, who studies it and how, and potential risks for civilization:

THE RACE TO UNDERSTAND ANTARCTICA’S MOST TERRIFYING GLACIER
https://www.wired.com/story/antarctica-thwaites-glacier-breaking-point/

It actually explains matters such as the implications of a retrograde glacier bed geometry, ice-cliff failure, and the proposal to construct an artificial sill, among other concepts that have been raised here.

32


https://onlinelibrary.wiley.com/doi/abs/10.1002/wcc.511

Abstract: "Climate change detection and attribution have proven unexpectedly challenging during the 21st century. Earth’s global surface temperature increased less rapidly from 2000 to 2015 than during the last half of the 20th century, even though greenhouse gas concentrations continued to increase. A probable explanation is the mitigation of anthropogenic warming by La Niña cooling and declining solar irradiance.

I think it could be argued that the period highlighted was blighted by the flip side of the global warming coin, that of global dimming? The fact the the Pacific was ground zero for the incredible increase in Chinese 'dimming' lead to imbalance between the tropical Pacific/tropical Atlantic.
In its turn this lead to the increase in upper level winds over the Caribbean as the basins struggled to find parity and this began to lower Atlantic hurricane numbers via the aggressive shear environment any forming storms encountered.
It also lead to the uptick in the trades over the ENSO regions leading to the huge warm pool at the western extremes of that area.

A combination of China's scrabble to clean up its urban pollution and so save the population ( nobody wants to only be able to see the sun via TV screens in the city centres!) and the flipping of the Pacific 'Naturals' in 2014 helped us suddenly balance out the Basins and so allow warming to return to above the rates of warming measured over the last spurt of warming post our 'dimmed period ( 1980's/90's ).

I know it is early doors yet but I think we will find the years up to 2025 warming at rates well above those of the late 20th century both via the clearing of the airs over the Pacific but also the impacts of open water Arctic ( and recently Antarctic?) able to capture energy that used to be bounced harmlessly back into space and introduce it into the climate system?


33
Thanks for the Rob DeConto presentation of March 30th 2018, ASLR.
From 56m-66m I find particularly interesting, where he talks about (quite arbitrary) speed limits for cliff failure in his model, and stretching these limits in newer versions, as yet unpublished, if I understand correctly. Also atmospheric modelling would seem to slow melt in the first decades (compared to an earlier version), but cliff failure could speed it up more later, it seems from what he says here.

34
Missed ya ASLR.  :)

35
AbruptSLR...just wanted to say that I am happy to see you still posting here.

36
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.

37
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.

38
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.

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Unfortunately litesong, no-one has invented a time machine that can take us back.
It's the speed that's the big issue here, followed by the speed and then in third place, the speed.

Using the Eeemian as an analogy, with Greenland as the new "cold pole" doesn't really work. First, we now know that the year-to-year variability in SMB can be high and is highly dependent on the weather. Second, the ice on Greenland covers "only" ~1,700,000 km², the Arctic Ocean ~14,000,000 km². Third, during the Eemian it was warmer summers that melted the ice thanks to different orbital parameters. Fourth, CO2 levels during the Eemian peaked around 280ppm.



Hopefully GRACE-FO starts producing soon. It won't help us mitigate though.

40
Are you sure about that Hefaistos?

41
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.

42
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. ...

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More supporting evidence that Climate Change is impacting polar drift

Scientists ID Three Causes of Earth's Spin Axis Drift
https://phys.org/news/2018-09-scientists-id-earth-axis-drift.html


The observed direction of polar motion, shown as a light blue line, compared with the sum (pink line) of the influence of Greenland ice loss (blue), postglacial rebound (yellow) and deep mantle convection (red). The contribution of mantle convection is highly uncertain.

Using observational and model-based data spanning the entire 20th century, NASA scientists have for the first time identified three broadly-categorized processes responsible for this drift—contemporary mass loss primarily in Greenland, glacial rebound, and mantle convection.

"The traditional explanation is that one process, glacial rebound, is responsible for this motion of Earth's spin axis. But recently, many researchers have speculated that other processes could have potentially large effects on it as well," said first author Surendra Adhikari of NASA's Jet Propulsion Laboratory in Pasadena, California. "We assembled models for a suite of processes that are thought to be important for driving the motion of the spin axis. We identified not one but three sets of processes that are crucial—and melting of the global cryosphere (especially Greenland) over the course of the 20th century is one of them."

While ice melt is occurring in other places (like Antarctica), Greenland's location makes it a more significant contributor to polar motion.

"There is a geometrical effect that if you have a mass that is 45 degrees from the North Pole—which Greenland is—or from the South Pole (like Patagonian glaciers), it will have a bigger impact on shifting Earth's spin axis than a mass that is right near the Pole," said coauthor Eric Ivins, also of JPL.


The results suggest that tracking polar shifts can serve as a check on current estimates of ice loss, says Erik Ivins, a geophysicist at NASA’s Jet Propulsion Laboratory in Pasadena, California. When mass is lost in one part of a spinning sphere, its spin axis will tilt directly towards the position of the loss, he says — exactly as Chen’s team observed for Greenland. “It’s a unique indicator of the point where the mass is lost,” says Ivins.

Scientists can locate the north and south poles to within 0.03 milliarcseconds by using Global Positioning System measurements to determine the angle of Earth’s spin. Knowing the motion of the poles constrains estimates of ice loss made by other methods, Chen says

With these three broad contributors identified, scientists can distinguish mass changes and polar motion caused by long-term Earth processes over which we have little control from those caused by climate change. They now know that if Greenland's ice loss accelerates, polar motion likely will, too.

JPL Interactive Polar Motion Simulator: https://vesl.jpl.nasa.gov/sea-level/polar-motion/

What drives 20th century polar motion?

https://www.sciencedirect.com/science/article/pii/S0012821X18305314

Quote
Abstract

Astrometric and geodetic measurements show that the mean position of Earth's spin axis drifted through the solid crust toward Labrador, Canada at an average speed of  cm/yr during the 20th century. Understanding the origins of this secular polar motion (SPM) has significance for modeling the global climate, as it provides a link to ice mass balance and sea-level rise. A perplexing issue, however, is that while glacial isostatic adjustment (GIA) models satisfactorily explain the direction of SPM, the associated prediction of the amplitude is insufficient. Our Bayesian GIA analysis, with constraints from relative sea-level and vertical land motion data, reveals that this process only accounts for % of the observed SPM amplitude. This shortfall motivates a more broadly scoped reassessment of SPM drivers. To address this, we assemble a complete reconstruction of Earth's surface mass transport derived from recent advancements in modeling the global 20th century cryospheric, hydrologic, oceanic, and seismogenic mass exchange. The summed signals, nonetheless, cannot fully reconcile the observed SPM, even when considering the error statistics of each driver. We investigate an additional excitation source: changes in Earth's inertia tensor caused by mantle convection. Sophisticated models have recently been advanced in tectonic plate reconstructions, in conjunction with geoid and seismic tomographic models. Here we use these models to compute new estimates of SPM. While the convection-driven SPM has considerable uncertainty, the average direction of 283 recent models aligns with the residual SPM (within 2.7 +/- 14.8 ), significantly reducing the gap between observation and prediction. We assert that one key mechanism for driving 20th century SPM is long-term mass movement due to mantle convection.

44
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/

45
While the linked research, indicating more rapid bedrock uplift in Amundsen Sea Embayment, seems like good news, if one refers to projections from ice sheet models that do not include Pollard's & DeConto's ice cliff and hydrofacturing mechanism and which assume radiative forcing scenarios of RCP 4.5 or less.  However, if one assumes radiative forcing scenarios close to BAU for the next two decades and projections from Pollard & DeConto's recent work, then Barletta et al (2018)'s finding are actually bad news regarding the potential collapse of the WAIS this century.

V.R. Barletta el al. (22 Jun 2018), "Observed rapid bedrock uplift in Amundsen Sea Embayment promotes ice-sheet stability," Science,:
Vol. 360, Issue 6395, pp. 1335-1339, DOI: 10.1126/science.aao1447.

http://science.sciencemag.org/content/360/6395/1335
Because there is a volcano beneath Pine Island Glacier, and because

Evidence of an active volcanic heat source beneath the Pine Island Glacier https://www.nature.com/articles/s41467-018-04421-3 and because there was a recent eruption

A recent volcanic eruption beneath the West Antarctic ice sheet https://www.nature.com/articles/ngeo106 Ancient Antarctic eruption noted http://news.bbc.co.uk/2/hi/science/nature/7194579.stm the uplift may mean that the heat source also advances. 


Quote
The localization of mantle helium to glacial meltwater reveals that volcanic heat induces melt beneath the grounded glacier and feeds the subglacial hydrological network crossing the grounding line. The observed transport of mantle helium out of the Ice Shelf cavity indicates that volcanic heat is supplied to the grounded glacier at a rate of ~ 2500 ± 1700 MW, which is ca. half as large as the active Grimsvötn volcano on Iceland. Our finding of a substantial volcanic heat source beneath a major WAIS glacier highlights the need to understand subglacial volcanism, its hydrologic interaction with the marine margins, and its potential role in the future stability of the WAIS.

ps. can someone suggest a good open study on Marine ice cliff instability?
Here https://www.sciencedirect.com/science/article/pii/S0012821X14007961

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Yes, the unloading of the ice sheet in the WAIS could produce increased volcanic activity over a geologically short period of time, and I fear that there is the possibility it might have a catastrophic affect within our life times. Every km of ice depth is replaced by 300 or so M of rock from isostatic rebound and, perhaps, by thick lava flows.

Note, though, that the tectonic's are very different to Iceland. The West Antarctic rift is a very slowly growing rift, and therefore the store of magma is probably low because the lithiosphere hasn't been thinning quickly. The WAR is spreading at about 2mm a year. Iceland sits on a hotspot that's also on a MOR that's spreading at an average rate 25mm a year (the fastest measured spreading on land is probably Greece, at 70+mm a year, in the oceans the EPR, spreads at 150mm a year). We didn't see a change in magnetism due to changes in the icesheet in Iceland, despite the unloading of ice and the massive increase in volcanism. I doubt very much we will see it in the Antarctic.




47

On Polar wander and reversals


It seems that there is a correlation between polar wander and reversals. And it seems that rapid ice melt correlates with polar wander. Note that these correlations are on vastly different timescales.

The first paper speculates that there is a causative mechanism that is due to changes in mantle/core boundary conditions, the dynamic convection changes in the mantle altering the shape of the earth and causing polar wander, and correlating with magnetic pole reversals from thermal changes at the core mantle boundary. The paper discussing convective changes backs up the fact that you get polar reversals when the convective pattern of the mantle changes.

Perhaps Ice unloading will change the shape of the Earth and shift the axis of rotation enough to change mantle convection, but it's unlikely; there is a lot more mantle than ice, it would be analogous to a small rock hitting a car and changing it's direction (mantle mass 4×10^27g, total ice mass, 2.4x10^22g). The mantle will eventually adjust to take into account the new shape of the earth after ice melt, but it's more than likely going to be down to Asthenospheric mantle compensation as is modeled in PGR, and that alone will take 1000's of years.

My guess is the polar wander caused by ice melt is just noise in the ancient signal.



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I have cited sections of this thread in the UK Houses of Parliament evidence on Section "4. The John Mercer Effect: the ‘Forbidden Line’ on Sea Level Rise". Unfortunately, due to the Parliament rules, I could not represent whole text as such but had to abbreviate and leave out few points. I am also rather sad because this was thought by many at one good solution for climate change. :'(

Our Changing Climate in Action: the Risk of Global Warming and the Environmental Damage from the Rising Ocean Water Table | Sustainable Seas Enquiry | Written evidence submitted by Veli Albert Kallio, FRGS (SSI0121) | Ordered to be published 23 May 2018 by the House of Commons.

Abstract:

Recently NATURE published a discussion on construction of sills in attempt to prevent or slow melting glaciers that are discharging ice into the ice fjords. Several further papers promptly followed publication of this essentially erroneous article in a respected NATURE magazine. Here it is pointed out that there is a discrepancy of several magnitudes thus excluding a long-term viability to manage the edges of ice fjords or continental ice shelves/sheets due to a phenomenon known as the mega-erratics. These are blocks of hard rocks that are several kilometres in size that have been dislocated by a warmed and wet edges of glacier/ice sheet/ice shelf. This Parliament evidence points out the error that was not apparent to the peer-reviewers at the time and in subsequent papers that followed. The Parliament was shown evidence that large enough obstacles cannot be possibly made to prevent ice discharges due to a progression of melting, that softens and lubricates glaciers, ice caps and ice sheets. The forces unleashed by the ice front exceeds several magnitudes from the conceived objects that sills were proposed. The only, and very only effect is temporary and limited to prevention of warm water incursion where these methods will work for a while in a cold, dry, and relatively stable ice formations.

Long-term projections suggested to prevent warmed and water-infested glaciers from discharging ice into the ocean cannot be made as the forces of ice exceed many magnitudes of the sills and levies that can be made of concrete blocks, aggregates or other materials. Thus the prevention of sea level rise by this method for centuries or millennia is not functional one and thus the mitigation and prevention of rubbish gyros in ocean, the supply of housing, nuclear and food production security must be looked at as solution by the ocean littoral states. Several examples of various types of risk to the sustainability of oceans have been presented in addition to the above exposed misconception. This comes with much regret as it appears that one 'hoped-for-solution' to manage the future climate change impacts has largely foundered on the issue that the sills cannot be made strong enough to contain most important, warmed glaciers or edges of unstable ice shelves. However, for a short-term this may offer small-scale solutions provided that costs remain sufficiently small. Aggressively melting ice formations with darkened surfaces, wide spread melt water ponds, or water filled crevasses it does not offer much, if any, prolonged ice stability. (The document is best viewed as a .pdf file due to the lay-out of graph and legends.)

https://www.academia.edu/37157851/Our_Changing_Climate_in_Action_the_Risk_of_Global_Warming_and_the_Environmental_Damage_from_the_Rising_Ocean_Water_Table_Sustainable_Seas_Enquiry_Written_evidence_submitted_by_Veli_Albert_Kallio_FRGS_SSI0121_Ordered_to_be_published_23_May_2018_by_the_House_of_Commons

Stopping the Flood: Could We Use Targeted Geoengineering to Mitigate Sea Level Rise?
Michael J. Wolovick1 and John C. Moore2,3
1Atmosphere and Ocean Sciences Program, Department of Geosciences, Princeton University, GFDL, 201 Forrestal Road,
Princeton, NJ 08540, USA
2College of Global Change and Earth System Science, Beijing Normal University, Beijing, China
3Arctic Centre, University of Lapland, Finland
Correspondence: M.J. Wolovick (wolovick@princeton.edu)

Abstract. The Marine Ice Sheet Instability (MISI) is a dynamic feedback that can cause an ice sheet to enter a runaway collapse. Thwaites Glacier, West Antarctica, is the largest individual source of future sea level rise and may have already entered the MISI. Here, we use a suite of coupled ice–ocean flowband simulations to explore whether targeted geoengineering using an artificial sill or artificial ice rises could counter a collapse. Successful interventions occur when the floating ice shelf regrounds 5 on the pinning points, increasing buttressing and reducing ice flux across the grounding line. Regrounding is more likely with a continuous sill that is able to block warm water transport to the grounding line. The smallest design we consider is comparable in scale to existing civil engineering projects but has only a 30% success rate, while larger designs are more effective. There are multiple possible routes forward to improve upon the designs that we considered, and with decades or more to research designs it is plausible that the scientific community could come up with a plan that was both effective and achievable. While 10 reducing emissions remains the short-term priority for minimizing the effects of climate change, in the long run humanity may need to develop contingency plans to deal with an ice sheet collapse.

--

http://data.parliament.uk/writtenevidence/committeeevidence.svc/evidencedocument/environmental-audit-committee/sustainable-seas/written/83150.pdf

49
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.

50
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

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