Support the Arctic Sea Ice Forum and Blog

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - AbruptSLR

Pages: [1] 2 3 ... 7
1
Sweden was Apr 4 last year, twenty days after the US and a boring guess for 2019 globally: Jul 30.

https://iopscience.iop.org/article/10.1088/1748-9326/aaf303

2
Reply #576 on: February 06, 2019, 08:17:33 PM
https://forum.arctic-sea-ice.net/index.php/topic,2205.msg188317.html#msg188317
Quote
Both DeConto and Pollard were originally co-authors on the new paper. They later recused themselves because they felt the results coming from Edwards’s statistical model were not consistent with what they were seeing from their own physics-based glacier model.

3
Quote
Title: "EIA's Annual Energy Outlook 2019 projects growing oil, natural gas, renewables production"
https://www.eia.gov/todayinenergy/detail.php?id=38112
That graph, ASLR, is depressing.  Renewables need to climb 2 orders of magnitude beyond the EIA's expectations to serious displace oil & gas.  The only good news is that the EIA is likely underestimating renewables - I hope by 2 orders of magnitude!

4
Glaciers Crumble and Sea Levels Rise In This New Weather Channel Immersive Mixed Reality Clip 
https://www.theverge.com/2019/4/9/18302006/sea-level-rise-charleston-norfolk-glaciers-climate-change-the-weather-channel



The scene is from The Weather Channel’s latest mixed reality segment, which connects the flooding of tomorrow to the melting glaciers and sea level rise of today.

5
Hansen is talking about the effect of ice sheet disintegration and freshwater hosing, which provides the obvious negative feedback and cooling but at the same time increases the planet's energy imbalance. See (b) in the image ASLR posted above, it's in section 3.4 of that paper.

Edit; might as well add the link: https://www.atmos-chem-phys.net/16/3761/2016/

6
Mornin', maybe I still don't follow but a static Antarctica would lower the planet's energy imbalance.

7
I haven't followed but maybe one of the two papers attached below?

Just popped in to post this nice(?) podcast with Glen Peters (one of the lead authors in WG6-AR3-Ch3):
https://kleinmanenergy.upenn.edu/energy-policy-now/hard-look-negative-emissions

8
Since we all know how 2018 ended (emissions wise), here's a nice and simple animation of our collective climate actions since 1965 by Robert Wilson:
https://twitter.com/countcarbon/status/1112430555021434882

Also noticeable are the disturbances caused by economic crises.

9
I find AbruptSLR to be a refreshing break from the UN Climate Circus prognostications, which continually use sleights of hand (ignoring increased natural emissions, restrictive confidence intervals, low values for climate sensitivity, ignoring the growth in methane levels, assumptions of massive rollouts of hypothetical technologies, assuming a frictionless rollout of renewables etc.) to be able to say that "we can still do it and keep growing" from every report.

His posts remind us that there definitely are possible climate devils out there which we should not be taking the risk of triggering - i.e. The Precautionary Principle. In addition the scientific community/policy keeps taking its time to catch up to the likes of Hansen and others.


10
While AbruptSLR is doing a great job in highlighting potential dangers of climate change, he is focusing on the very low-probability extreme climate change scenarios. If you read the articles he links to, they often focus on hypothetical extreme model runs to show what could happen in the case of runaway carbon emissions. He has recently posted papers with 4 times increases in CO2 concentrations and 5 or 11 times increases in methane concentrations. Those are scenarios well beyond even the extremes of RCP 8.5.
[...]
Also, renewable energy is now cheaper than coal and is quickly becoming cheaper than natural gas and EVs are poised to outsell ICEs in the coming decade. As a result, we're probably going to end up on an emissions path between RCP 2.6 and 4.5.
So there are many reasons to hope. I agree with AbruptSLR and many posters on this site that we need to get off of fossil fuels as quickly as possible and I also agree with the consensus climate scientists that it's not too late. Don't give up hope.

I never read ASLR's posts as a reason for despair. On the contrary: he shows the urgency of taking the collective action that can at this point hopefully still prevent the worst-case risks from materializing. Many mainstream communications focus on current best-estimates, without being or making people aware of the severe fat tail risks. Sutton 2018 proposes to improve on this lack of clear risk communication by using this simple figure below that shows the probability of very high climate sensitivity and its likely impacts, concluding that the highest risk is in the small, but significant chance of very high climate sensitivity and related impacts:
https://www.earth-syst-dynam.net/9/1155/2018/

Not being aware of this risk increases the chance of insufficient collective climate action (mitigation and adaptation), and would therefore increase the chance of eventual depair, in case worst-case scenario's would turn into reality. Since we don't know the real probability distribution for sure, we're in a situation of deep uncertainty, which makes strong climate action all the more urgent as a precaution against finding out that a high climate sensitivity appears to be more likely than mainstream science thought so far.

Very well said Lennart; probabilities with deep uncertainty really don't tell us much beyond the current state of our thinking. Or in this case, the current state of thinking that all the panelists (and the political overseers) on the IPCC can agree on.

11
While AbruptSLR is doing a great job in highlighting potential dangers of climate change, he is focusing on the very low-probability extreme climate change scenarios. If you read the articles he links to, they often focus on hypothetical extreme model runs to show what could happen in the case of runaway carbon emissions. He has recently posted papers with 4 times increases in CO2 concentrations and 5 or 11 times increases in methane concentrations. Those are scenarios well beyond even the extremes of RCP 8.5.
[...]
Also, renewable energy is now cheaper than coal and is quickly becoming cheaper than natural gas and EVs are poised to outsell ICEs in the coming decade. As a result, we're probably going to end up on an emissions path between RCP 2.6 and 4.5.
So there are many reasons to hope. I agree with AbruptSLR and many posters on this site that we need to get off of fossil fuels as quickly as possible and I also agree with the consensus climate scientists that it's not too late. Don't give up hope.

I never read ASLR's posts as a reason for despair. On the contrary: he shows the urgency of taking the collective action that can at this point hopefully still prevent the worst-case risks from materializing. Many mainstream communications focus on current best-estimates, without being or making people aware of the severe fat tail risks. Sutton 2018 proposes to improve on this lack of clear risk communication by using this simple figure below that shows the probability of very high climate sensitivity and its likely impacts, concluding that the highest risk is in the small, but significant chance of very high climate sensitivity and related impacts:
https://www.earth-syst-dynam.net/9/1155/2018/

Not being aware of this risk increases the chance of insufficient collective climate action (mitigation and adaptation), and would therefore increase the chance of eventual depair, in case worst-case scenario's would turn into reality. Since we don't know the real probability distribution for sure, we're in a situation of deep uncertainty, which makes strong climate action all the more urgent as a precaution against finding out that a high climate sensitivity appears to be more likely than mainstream science thought so far.

12
The consequence of that warming is seen in Banks Island thaw slumps:  Extremes of summer climate trigger thousands of thermokarst landslides in a High Arctic environment
  Antoni G. Lewkowicz & Robert G. Way  -  Nature Communications volume 10, Article number: 1329 (2019)

Abstract:
Quote
Retrogressive thaw slumps (RTS) – landslides caused by the melt of ground ice in permafrost – have become more common in the Arctic, but the timing of this recent increase and its links to climate have not been fully established. Here we annually resolve RTS formation and longevity for Banks Island, Canada (70,000 km2) using the Google Earth Engine Timelapse dataset. We describe a 60-fold increase in numbers between 1984 and 2015 as more than 4000 RTS were initiated, primarily following four particularly warm summers. Colour change due to increased turbidity occurred in 288 lakes affected by RTS outflows and sediment accumulated in many valley floors. Modelled RTS initiation rates increased by an order of magnitude between 1906–1985 and 2006–2015, and are projected under RCP4.5 to rise to >10,000 decade−1 after 2075. These results provide additional evidence that ice-rich continuous permafrost terrain can be highly vulnerable to changing summer climate.

paper and pictures at link



13
Reading some of Radoslav Dimitrov's articles on the UN FCCC processes (he was a delegate at Copenhagen and Paris) helps show what a political circus it is. He calls the Copenhagen Accord and Paris Agreement "decoy institutions" meant to hide the reality of a lack of any real progress.

Thanks for the reference to Dimitrov. It seems he indeed calls the Copenhagen Accord a decoy institution, but leaves the question open on the Paris Agreement (Dimitrov 2018):
https://www.researchgate.net/profile/Radoslav_Dimitrov/project/Decoy-institutions-in-world-politics/attachment/5ba286483843b006753a259a/AS:672625667887109@1537377864774/download/+Decoy+Institutions+-R.+Dimitrov.pdf?context=ProjectUpdatesLog

"Is the Paris Agreement on Climate Change, for instance, a decoy institution? The agreement is characterized by remarkable complexity and is not a conventional treaty that conforms easily to the traditional model of international law. It relies on a complex mix between legally binding obligations and voluntary provisions that give full discretion to governments. This ambiguity leads to various interpretations and vigorous debates but, mostly, genuine uncertainty in academic circles. Some observers claim there are no legal obligations for action, and even decry it as a misleading nonbinding agreement that is camouflaged as a treaty. Others disagree and insist the Paris Agreement is a treaty with real policy obligations. Even veteran IR scholars of global governance appear at a loss and state cautiously that the vagueness of the Paris Agreement creates uncertainty about its effectiveness. The possibility that this treaty is actually an elaborate decoy institution that allows governments to hide behind a weak international arrangement could clarify the situation and deserves investigation."

In 2016 he did seem to think the Paris Agreement was a genuine diplomatic success:
http://politicalscience.uwo.ca/people/faculty/full-time_faculty/GEP%20Paris%20Agreement.pdf

"The Paris Agreement constitutes a political success in climate negotiations and traditional state diplomacy, and offers important implications for academic research. Based on participatory research, the article examines the political dynamics in Paris and highlights features of the process that help us understand the outcome. It describes battles on key contentious issues behind closed doors, provides a summary and evaluation of the new agreement, identifies political winners and losers, and offers theoretical explanations of the outcome. The analysis emphasizes process variables and underscores the role of persuasion, argumentation, and organizational strategy. Climate diplomacy succeeded because the international conversation during negotiations induced cognitive change. Persuasive arguments about the economic benefits of climate action altered preferences in favor of policy commitments at both national and international levels."

14
The UNFCCC and IPCC have turned into a device to enable growth while keeping the pressure for more fundamental change at bay by creating a mirage of real progress. Every time there is a clash between the need to reduce GHG emissions and growth another rabbit is pulled out of the hat - such things as the inclusion of BECCS and DACS, the manipulation of confidence intervals, and the usage of low estimates for climate sensitivity.

It does look like the science is starting to remove some of the rabbits (e.g. low estimates of climate sensitivity) and the confidence interval cant be messed with any more (the 50% for 1.5 degrees was the lowest that I think they can get away with). The continued increase in atmospheric CH4 is also adding pressure. So the new rabbits for the 2022 IPCC report may be even greater use of BECCS/DACS, plus maybe rock weathering and SRM?

Reading some of Radoslav Dimitrov's articles on the UN FCCC processes (he was a delegate at Copenhagen and Paris) helps show what a political circus it is. He calls the Copenhagen Accord and Paris Agreement "decoy institutions" meant to hide the reality of a lack of any real progress.


15
I agree that the IPCC has mishandled uncertainty and the carbon budgets are based on false confidence. The IPCC has ignored processes that have been identified but not well quantified. There may be processes not yet discovered. What we have learned between each iteration of the IPCC reports has tended to discover that the climate is more sensitive to GHGs than previously estimated.

A better handling of uncertainty would lead to less confidence in budgets and more urgency for action because the uncertainties skew towards higher impacts of GHGs on climate change.

16
So what's the controversy?

In short, RCP2.6. Graph posted by Zeke Hausfather:




zeke's work was a total hack job as the AMAP report shows direct observations that are ALREADY higher than what he projects under RCP 2.6.  Note that he is also looking at 2100 values not peak warming under 2.6  (he is counting on significant cooling after 2040 with no loss of sea ice (in fact recovery).

we had an exchange here:  https://twitter.com/hausfath/status/1108068566689996800

17
Thank you ASLR for taking the time to reply.

I had been taught that Arctic was 66 to 90, but thought that maybe there was some unusual convention amongst climate scientists for using a larger area, kind of like using 1985-2005 as a pre-industrial baseline...

I greatly appreciate all your posts here. Thanks again.

18
I think, telling us this, is the whole purpose of this thread, isn't it AbruptSLR?

It doesn't have to be the purpose, but could be a consequence/conclusion.

19
So what's the controversy?


As a short note, wdmn’s plot is linked in the long-term ASI blog graphs of observed data.  However it is for 67 to 90N instead of 60 to 90N.

Thank you for the clarification. Looking at the source of gerontocrat's data, it seems as though his graph covers 64-90N.

Sorry for going slightly off topic, but...

So if I have this straight, the main gripe is with the claim that even if we were to meet the Paris objectives the warming would be locked in, since the projections used were from RCP 4.5, which is less ambitious than the Paris targets. Moreover values were not used for the full arctic (60-90N).

While I agree that accuracy is important, and appreciate Zeke's work on this, it really is obscene to be carrying on this debate as though we're still serious about the possibility of keeping warming well below 2C given what other recent studies have said, and the early results for ECS from CMIP6.

In the U.S. plans for oil extraction surge on. In Canada, where I live, it looks as though the conservatives will be winning in Alberta this year. One conservative commentator from that province was on CBC radio this weekend talking about how it will take 10 years to get the oil and gas industry back to where it was. i.e. there are no plans to leave anything in the ground.

Meanwhile there is this huge terror of admitting that we might be too late to reach 1.5, let alone 2C, to the point where we're likely to get caught with our pants down over the coming decade, and I sometimes wonder if relying on the IPCC and the RCP pathways is the new predominant form of denial.

20
So what's the controversy?

In short, RCP2.6. Graph posted by Zeke Hausfather:


I commented this on a Swedish blog a week ago, my summary was that Zeke Hausfather is correct, UN stumbled on the scenarios and AMAP will probably be closest to reality with Fig 2.13.
Who believes in RCP2.6, certainly not the model itself (~4C annual and ~5C winter warming by 2100 relative to preindustrial) or that the world will follow a path close to it?

21
"countries manage to cut GHG emissions to the targets outlined in the 2015 Paris Agreement on climate change, winter temperatures in the Arctic will still be 3 to 5°C higher by 2050 and 5 to 9°C higher by 2080, relative to 1986–2005 levels. In fact, even if we stopped all emissions overnight, winter temperatures in the Arctic will still increase by 4 to 5°C compared to the late twentieth century."

Anthropocene commented #756 in the "Places becoming less livable" thread on the misquote in the Guardian re. Preindustrial when the UN paper says 3-5 C higher is relative to 1986-2005 levels.

https://gridarendal-website-live.s3.amazonaws.com/production/documents/:s_document/465/original/GlobalLinkages.pdf?1552478695



22
They just woke up to the reduced ice albedo effect? On a CO2e basis, we are already beyond 550ppm.

23
Tall Ice-Cliffs Trigger Big Calving Events—and Fast Sea-Level Rise 
https://phys.org/news/2019-03-tall-ice-cliffs-trigger-big-calving.html

... Although much calving occurs when the ocean melts the front of the ice, and ice cliff above falls down, a new study presents another method of calving: slumping. And this process could break off much larger chunks of ice at a quicker rate.

... the research team noted that features on Helheim glacier are typical of what you might see in a slump-prone terrestrial landscape and they wondered if ice might suffer the same fate. "You've got a crevasse that serves as a head scarp and then you've got the stresses [within the ice] maximized down at the water level," he says.

To test if slumping occurs on ice cliffs, the team monitored Helheim glacier during a calving event, using real-aperture terrestrial radar interferometery. They measured speed, position, and motion of the calving ice. The researchers observed an ice-flow acceleration just before an initial slump, followed by a rotating, full ice-thickness calving of the glacier—including the entire remaining ice-cliff, reaching both above and below the water line.

Removing the weight of the upper ice by slumping encourages the underlying ice to pop upward. "Because it's still attached at the back, it's going to rotate a little bit," says Alley. The rotation causes a crack to form at the bottom of the glacier as the ice flexes. In turn, the crack can weaken the ice, creating a large calving event—all triggered by the initial slump on top of the ice cliff. ...

... With slumping, the calving occurs without waiting for the melt. "We'll go slump... basal crevasse... boom," he says, noting that when the calving happens it will take the 100 meters of ice above the water—and the 900 meters below the water—very quickly.

And 1000 meters of ice calving at once isn't the limit. Alley says that in some places in Antarctica, the glacial ice bed can be 1500 to 2000 meters below sea level, creating a much taller cliff above water. He says the worry is that taller cliffs are even more susceptible to slumping. "The scary thing is that if pieces of west Antarctica start doing what Helheim is doing, then over the next hundred years, models indicate that we get rapid sea level rise at rates that surpass those predicted," says Alley. 


Byron R. Parizek et al. Ice-cliff failure via retrogressive slumping, Geology (2019)

24
Nice mini-thread by Glen Peters here on emission scenarios:
https://twitter.com/Peters_Glen/status/1107923815508701184
For fossil CO₂ emissions, we started to move onto track, but that quickly changed…

25
We are not yet certain what the impacts of our current geoengineering project over the last 200 years will look like and we have been studying this fairly intently for the better part of 40 years. There is no way we can predict fully the effects of future projects. We should expect unintended, unanticipated and quite painful consequences of our hubris in approaching climate change as an engineering problem to be solved.

Never the less, given our refusal to halt the current project, we should expect many increasingly frantic projects, implemented far to quickly in the very near future.

May the Goddess help us.

26
Re 744.

Have you seen the news in #64 here.

https://forum.arctic-sea-ice.net/index.php/topic,2449.msg191933.html

"The plant assemblages indicate that there was an abrupt and major shift in the vegetation from wet, cold conditions at Pilauco to warm, dry conditions," Kennett said. According to him, the atmospheric zonal climatic belts shifted "like a seesaw," with a synergistic mechanism, bringing warming to the Southern Hemisphere even as the Northern Hemisphere experienced cooling and expanding sea ice.

They could be related?

27
Game Over Man; Game Over! ...

Few Pathways to an Acceptable Climate Future Without Immediate Action
https://phys.org/news/2019-03-pathways-climate-future-action.html

...The massive analysis shows that meeting the 2.00 C target is exceptionally difficult in all but the most optimistic climate scenarios. One pathway is to immediately and aggressively pursue carbon-neutral energy production by 2030 and hope that the atmosphere's sensitivity to carbon emissions is relatively low, according to the study. If climate sensitivity is not low, the window to a tolerable future narrows and in some scenarios, may already be closed.

... If the climate sensitivity is greater than 3.00K (median of assumed distribution), the pathway to a tolerable future is likely already closed. 



Robust abatement pathways to tolerable climate futures require immediate global action, Nature Climate Change (2019).

28
This EPA report from 1983 showed 2°C in 2040.
Record emissions in 2018 and continuing warm ENSO conditions projected for 2019 won't delay warming.

Can we delay a greenhouse warming?
The Effectiveness and Feasibility of Options to Slow a Build-up of Carbon Dioxide in the Atmosphere

https://cfpub.epa.gov/ols/catalog/advanced_brief_record.cfm?&FIELD1=AUTHOR&INPUT1=STEPHEN%20AND%20L.&TYPE1=ALL&LOGIC1=AND&COLL=&SORT_TYPE=MTIC&item_count=34&item_accn=61312
http://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=9101HEAX.PDF

29
Just want to thank you AbruptSLR for your ongoing posting of these fascinating abstracts, links and your accompanying comments. I wouldn't know where to begin to find all this stuff out but you manage to to distill it out in wonderful digest. Most appreciative.
Tony

30
Some interesting reflections by Dewi Le Bars on the implications of two recent papers for the projections by DeConto & Pollard and for ice-climate feedback modelling (as proposed by Hansen et al, amongst others):
https://sites.google.com/site/dewilebars/sea-level-monthly-review/february-2019

On Edwards et al 2019:
'The claim that MICI is "not necessary" to reproduce past sea level high stands is both not really true and not really useful. The uncertainty range about what could have been the contribution of Antarctica to sea level during the Pliocene is 5-20 m and during the Last Interglacial it is 3.6-7.4 m. DeConto and Pollard’s model without MICI can reproduce up to 6 m and 5.5 m respectively for these two period (see Edwards et al. E.D. Fig. 4). So yes it can reproduce the lower part of the ranges. But most of the Pliocene range cannot be reproduced with the no-MICI assumption. What the figure shows is that the model with MICI covers a much bigger par of the possible Antarctic contribution for these periods. And still, even including MICI, the model can only explain a maximum of 12 m contribution for the Pliocene. Which means additional mechanisms would be necessary to cover the whole range of possible Antarctic contribution for that period. The claim that MICI is “not necessary” is also not very useful practically because projections with MICI are used to make high-end sea level scenarios. The important information is then is it possible or not? If it was not possible then it would be good news and decision makers wouldn't need to take it into account. "Not necessary" only has an impact on low-end scenarios, for which MICI would already not be used anyways.'

On Golledge et al 2019:
'Current state of the art (CMIP5 type) climate models do not include ice sheet models so the coupled effects between ice sheets and climate are a blind spot. In these climate models the ice sheets are just white mountains that do not change over time. They might have a snow layer on top of them but no ice. So snow falls on them accumulate a little bit and when it melts it is put in the nearest ocean grid box. If too much accumulates then it is put directly in the ocean to avoid infinite accumulation. What is missing is a model to transform the snow to ice and then transport it back to the sides of the ice sheet or to the ocean under the force of gravity. This is what ice sheet models do. Golledge et al. use the PISM ice sheet model for Greenland and Antarctica and couple them offline to LOVECLIM, an intermediate complexity climate model. Intermediate complexity means lower resolution and simpler physics compared to CMIP5 type climate models. It is the type of models generally used for long paleoclimate simulations.

What they find is that allowing feedbacks between the ice sheets and the climate model leads to strengthen both Antarctic and Greenland mass loss, by 100% and 30% respectively. For Antarctica this is not a surprise, although the magnitude is much bigger than I expected. Freshwater from the melting of ice leads to increase the ocean stratification, because it is is very light. This reduces vertical ocean mixing and as a result the surface of the ocean cools down while the subsurface warms up. Antarctica mostly looses mass from ice shelves basal melt and calving which is strengthened by warmer subsurface ocean temperature. For Greenland, it comes as a surprise to me that the feedback would increase the mass loss, because Greenland mostly looses mass from surface melt and a cooler atmosphere temperature would tend to reduce surface melt. Unfortunately the paper does not explain the mechanisms at play there (or did I miss it?).

There are a few issues with the ice sheet models that reduce my confidence in the projections. For Greenland the model is not able to reproduce the recent fast mass loss acceleration. Therefore the authors artificially impose the mass loss on the model in two ways: (1) decrease the friction between the ice and the bed (basal traction) to have a faster flow between 2000 and 2015 and (2) reduce the snowpack refreezing between 2000 and 2025. Refreezing is important for the mass balance because on ice sheets more than half of the snow that melts in the summer refreezes locally. It never reaches the ocean. Michiel van den Broeke had a similar comments in Trouw (in Dutch). You can force the model to agree with observations but if the model does not have the proper dynamics to explain observations there is no reason it is doing a good job for the future. For Antarctica, the model starts with enormous mass accumulation (1000 Gt/year in 1900) and accumulates mass until the 1980th. This is clearly not possible, such an accumulation would have been seen by tide gauge measurements. In fact as I said in the last review it is expected that Antarctica was slowly loosing mass in the 20th century. Also, the internal variability of grounded ice is so large in the model (Fig. 1a-d) that I do not understand what is going on physically (please let me know if you do).

In conclusion, the paper’s goal is important and it is the first time that two high resolution ice sheet models are coupled to a climate model. This is a big step in the right direction. However, I am not convinced by the results because of the issues mentioned above concerning the ice sheet models. Nevertheless, it is very instructive as it shows the long way that is left for ice sheet models to reach the level at which we can trust their future projections.'

31
Thanks for all the updates here!
No offense but the last one was posted yesterday by ASLR, gc.

When reading the discussion around Bentley I started thinking about this study about the mantle thermal anomalies beneath it. You guys are probably aware of it:
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015JB012455

32
Sea Ice Plays Pacemaker Role in Abrupt Climate Change
https://phys.org/news/2019-03-sea-ice-pacemaker-role-abrupt.html

A new study looking at variations in past sea ice cover in the Norwegian Sea found the shrinkage and growth of ice was instrumental in several abrupt climate changes between 32,000 and 40,000 years ago.

The growth or shrinkage of sea ice is often viewed as a symptom of climate change, but new research shows it may have played a more causative role in abrupt climate changes thousands of years ago.

The study, which was led by Dr. Henrik Sadatzki from the Department of Earth Science and Bjerknes Centre for Climate Research, University of Bergen (Norway), analysed marine sediment cores from the Norwegian sea to reconstruct changes in sea ice during the last glacial period, focusing on the abrupt climate change events. This was complemented by climate model simulations of the last glacial period.

The abrupt climate changes – known as Dansgaard–Oeschger climate events – had global implications and comprised temperature shifts of up to 15°C over the Greenland ice sheet and happened within decades.

While the underlying mechanisms of these dramatic changes are not yet fully understood, the study confirms that changes in sea ice cover in the Norwegian Sea played a key role in driving the enigmatic events.

Open Access: Henrik Sadatzki et al. Sea ice variability in the southern Norwegian Sea during glacial Dansgaard-Oeschger climate cycles, Science Advances (2019).

33
Kent A. Peacock (12 Sep 2018) "A Different Kind of Rigor: What Climate Scientists Can Learn from Emergency Room Doctors", Ethics, Policy & Environment, Volume 21, 2018 - Issue 2, Pages 194-214, https://doi.org/10.1080/21550085.2018.1509483
https://www.tandfonline.com/doi/full/10.1080/21550085.2018.1509483

Peacock says:
"There is a genuine possibility, however, remote, that the whole contents of the Bentley trench could shatter in a matter of weeks or months, raising global mean sea level by 3 m or more almost immediately."

What peer-reviewed publication supports this statement? I think Pollard, DeConto & Alley 2015 have said they can't rule out this is possible in a matter of "decades" (3m in 3 decades?):
https://www.sciencedirect.com/science/article/pii/S0012821X14007961

"In summary, applying a simple Pliocene-like warming scenario to our model, the combined mechanisms of MISI, melt-driven hydrofracturing and cliff failure cause a very rapid collapse of West Antarctic ice, on the order of decades."

I have not seen "weeks or months". Anyone else?

34
also nifty with sea level rise...

https://www.sealevels.org/

35
The linked article indicates that many climate scientists are worried about the recent increase in atmospheric methane concentrations (see the attached image).

Title: "Methane in the atmosphere is surging, and that’s got scientists worried"

https://www.latimes.com/science/sciencenow/la-sci-sn-methane-atmosphere-accelerating-20190301-story.html

Nice interactive atmospheric methane chart...

https://www.methanelevels.org/

36
The linked reference and associated article (& the first image) indicate that the number of global average ocean heatwave days has tripled in recent years.

Every chart I have seen tracking some component of climate change shows an exponential trend. This heat wave chart is no exception.

37
The first two associated linked sources indicate both that Arctic cloud cover is a net positive feedback mechanism and that Arctic cloud formation is highly enhanced (more so than in most other areas of the Earth) by the presence of aerosols.  These sources warn that allowing increase ship traffic into the Arctic Ocean would thus increase Arctic Amplification more than previously assumed.

Title: "Arctic Clouds Highly Sensitive to Air Pollution"

https://eos.org/scientific-press/arctic-clouds-highly-sensitive-to-air-pollution


Q. Coopman et al. (09 November 2017), "High Sensitivity of Arctic Liquid Clouds to Long‐Range Anthropogenic Aerosol Transport", Geophysical Research Letters, https://doi.org/10.1002/2017GL075795

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1002/2017GL075795

These are gold, especially the second one.

38
Concerning sulfur and shipping - mentioned above - I do not know how well the new IMO (International Maritime Organization) 2020 regulations are known to you.

From 2020 Jan 1, the sulfur content of fuel used by ships will be reduced from 3,5% to 0,5% (yes, from three-and-a-half to half percent). That is a major change and is going to happen very soon:

see for example here:

http://www.seatrade-maritime.com/images/PDFs/SOMWME-whitepaper_Sulphur-p2.pdf

39
Re: Radko

After thinking about it some more, I wonder if the instability against layering manifests in the Southerm Hemisphere ? CDW and neighbours are quite different from AMOC but the analysis seems quite general. I shall have to reread Dutrieux and others, in particular Hellmer on warm/cold cavities under ice shelves, in this light. The ocean transects by the current Thwaites effort should illuminate.

sidd
 

40
Re: Radko

I have read the paper more carefully and it does have this to say about diffusive heat transport and sea ice melt:

" Turner (2010) concludes that diffusive convection has contributed significantly to the observed increase in sea ice melting during the past few decades. Polyakov et al. (2017) reinforce this suggestion by demonstrating that the impact of the diffusive heat transport from AW on the sea ice loss in the Eurasian Basin is now comparable to, or possibly exceeds, the level attributed to atmospheric forcing. The staircase region today is about 100 m shallower, and layer thicknesses have doubled in comparison to measurements taken in 1985 (Padman & Dillon, 1987; Timmermans et al., 2008). The systematic increase in mean layer thickness, in turn, implies the systematic amplification of diffusive heat transport. Remarkably, despite the undeniable significance of thermohaline staircases for high‐latitude ocean dynamics, the physical mechanism of their formation has not been fully explained after more than half a century of observation.

Another diffusively generated phenomenon that is widespread in polar oceans is thermohaline interleaving (e.g., Rudels et al., 2009). Interleaving is characterized by lateral intrusive flows that mix adjacent water masses with different T‐S properties (Ruddick & Kerr, 2003; Ruddick & Richards, 2003). Fully developed intrusions are readily recognized in temperature and salinity profiles by alternating patterns of positive and negative vertical T‐S gradients. In the Arctic, intrusions spread relatively warm and salty AW from boundary currents at the basin periphery into fresher and colder interior regions. They can reach extraordinary large scales of up to a hundred meters in height and remain laterally coherent over hundreds of kilometers (e.g., Carmack et al., 1999; Merryfield, 2002)."

sidd

41
The linked article cites just one of many reasons why modern society is rapidly headed towards Pliocene conditions:

Title: "Sharp rise in methane levels threatens world climate targets"

https://www.theguardian.com/environment/2019/feb/17/methane-levels-sharp-rise-threaten-paris-climate-agreement

Extract: "Dramatic rises in atmospheric methane are threatening to derail plans to hold global temperature rises to 2C, scientists have warned."

The short version of this article is there has been a sharp rise in methane in the last decade and we don't know why. I don't like uncertainty as this does not allow us to identify an effective response.

42
good find,  I also predict that, if Asian Aerosols are reduced, we will see a much stronger shift o positive IPO states and these aerosol reductions will also produce increased regional warming (independent of the IPO impacts)

https://media.nature.com/original/nature-assets/nclimate/journal/v6/n10/extref/nclimate3058-s1.pdf



The linked reference adds information to Bamber's observation that the Arctic Ocean could become seasonally sea ice free circa 2040 (which would accelerate the ice-climate positive feedback mechanism):

J. A. Screen & C. Deser (05 February 2019), "Pacific Ocean Variability Influences the Time of Emergence of a Seasonally Ice‐Free Arctic Ocean", Geophysical Research Letters, https://doi.org/10.1029/2018GL081393

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GL081393

Abstract

The Arctic Ocean is projected to become seasonally ice‐free before midcentury unless greenhouse gas emissions are rapidly reduced, but exactly when this could occur depends considerably on internal climate variability. Here we show that trajectories to an ice‐free Arctic are modulated by concomitant shifts in the Interdecadal Pacific Oscillation (IPO). Trajectories starting in the negative IPO phase become ice‐free 7 years sooner than those starting in the positive IPO phase. Trajectories starting in the negative IPO phase subsequently transition toward the positive IPO phase, on average, with an associated strengthening of the Aleutian Low, increased poleward energy transport, and faster sea‐ice loss. The observed IPO began to transition away from its negative phase in the past few years. If this shift continues, our results suggest increased likelihood of accelerated sea‐ice loss over the coming decades, and an increased risk of an ice‐free Arctic within the next 20–30 years.

Plain Language Summary
Manmade climate change is causing a rapid loss of Arctic sea ice. Summer Arctic sea ice is predicted to disappear almost completely by the middle of this century, unless emissions of greenhouse gases are rapidly reduced. The speed of sea‐ice loss is not constant over time, however. Natural climate variability can add to the manmade decline, leading to faster sea‐ice loss, or can subtract from the manmade decline, leading to slower sea‐ice loss. In this study, we looked at how natural climate variability affects the timing of an ice‐free Arctic. We found that a natural cycle called the Interdecadal Pacific Oscillation, or IPO for short, is particularly important. Arctic sea‐ice loss is faster when the IPO is moving from its cold to warm phase and slower when the IPO is moving from its warm to cold phase. This is because variations in the IPO cause changes in atmospheric wind patterns, which alter the amount of heat that is transported into the Arctic. Observations show that the IPO started to shift from its cold to warm phase in the past few years. If this shift continues, our results suggest that there is an increased chance of accelerated sea‐ice loss over the coming decades.

43
As a follow-on to my Reply #633, the attached image from the linked reference indicates that EECO (Early Eocene Climate Optimum 51 to 53 million years ago, which had an equable climate), likely had much lower atmospheric carbon dioxide concentrations (circa 680ppm) that assumed by consensus climate science.  If so, it is likely easier to transition to an equable climate in modern times than assumed by consensus climate science:

Jagniecki,Elliot A. et al. (2015), "Eocene atmospheric CO2 from the nahcolite proxy", Geology, http://dx.doi.org/10.1130/G36886.1

in the abstract the lower limit constraint is 680 and the upper limit constraint is 1260 ppm. 

If we reached an equitable climate condition, the near term pulse from permafrost alone (first 300 years) would push the atmosphere CO2 well above the median value of ~1000 ppm.

44
Allow me AbruptSLR,

Very strong atmospheric methane growth in the four years 2014‐2017: Implications for the Paris Agreement (doi.org/10.1029/2018GB006009)

Abstract
Atmospheric methane grew very rapidly in 2014 (12.7±0.5 ppb/yr), 2015 (10.1±0.7 ppb/yr), 2016 (7.0± 0.7 ppb/yr) and 2017 (7.7±0.7 ppb/yr), at rates not observed since the 1980s. The increase in the methane burden began in 2007, with the mean global mole fraction in remote surface background air rising from about 1775 ppb in 2006 to 1850 ppb in 2017. Simultaneously the 13C/12C isotopic ratio (expressed as δ13CCH4) has shifted, in a new trend to more negative values that have been observed worldwide for over a decade. The causes of methane's recent mole fraction increase are therefore either a change in the relative proportions (and totals) of emissions from biogenic and thermogenic and pyrogenic sources, especially in the tropics and sub‐tropics, or a decline in the atmospheric sink of methane, or both. Unfortunately, with limited measurement data sets, it is not currently possible to be more definitive. The climate warming impact of the observed methane increase over the past decade, if continued at >5 ppb/yr in the coming decades, is sufficient to challenge the Paris Agreement, which requires sharp cuts in the atmospheric methane burden. However, anthropogenic methane emissions are relatively very large and thus offer attractive targets for rapid reduction, which are essential if the Paris Agreement aims are to be attained.

Plain Language Summary
The rise in atmospheric methane (CH4), which began in 2007, accelerated in the past four years. The growth has been worldwide, especially in the tropics and northern mid‐latitudes. With the rise has come a shift in the carbon isotope ratio of the methane. The causes of the rise are not fully understood, and may include increased emissions and perhaps a decline in the destruction of methane in the air. Methane's increase since 2007 was not expected in future greenhouse gas scenarios compliant with the targets of the Paris Agreement, and if the increase continues at the same rates it may become very difficult to meet the Paris goals. There is now urgent need to reduce methane emissions, especially from the fossil fuel industry.

Link >> https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2018GB006009

45
Thanks for the link to Purkey, i always read her. I note that Johnson is on this one too, and some of the usual suspects. Pity ARGO don't go that deep. Yet.

I hope she's doing one on the whole southern hemisphere, rather than just the Pacific.

"Here, we have shown that the AABW throughout the South Pacific has warmed, with
a possible slight acceleration in the most recent decade. The warming is accompanied by a
clear bottom-intensified freshening, strongest in the Ross Sea and Amundsen-Bellingshausen
Basin, but with early signs of the arrival of a fresher variety of AABW to the Southwest
Pacific Basin seen in the 2016/17 occupations of P15 and P06. The warming for P > 4000 m
is equivalent to an accumulation of energy at a rate of 3.5 (±0.1) MW in the deep ocean and
drives a local SLR of 0.14 (±0.04) mm yr -1 from thermal expansion, making it an important
contributor to ocean heat uptake and SLR."

That bit about recent freshening in the southwest pacific might be linked to Totten and neighbours.

I attach fig 5, note that the Amundsen-Bellinghausen is the only one cooling at depths above 3000dbar( roughly the same as meters)

sidd

46
We should get a fair hearing from this fellow ... /sarc

White House Creating Panel to Question Intelligence Agencies’ Finding That Climate Change Threatens National Security
https://www.washingtonpost.com/national/health-science/white-house-readies-panel-to-assess-if-climate-change-poses-a-national-security-threat/2019/02/19/ccc8b29e-3396-11e9-af5b-b51b7ff322e9_story.html



The White House is working to assemble a panel to assess whether climate change poses a national security threat, according to documents obtained by The Washington Post, a conclusion that federal intelligence agencies have affirmed several times since President Trump took office.

The proposed Presidential Committee on Climate Security, which would be established by executive order, is being spearheaded by William Happer, a National Security Council senior director.

Happer, an emeritus professor of physics at Princeton University, has said that carbon emissions linked to climate change should be viewed as an asset rather than a pollutant.


The initiative represents the Trump administration’s most recent attempt to question the findings of federal scientists and experts on climate change and comes less than three weeks after Director of National Intelligence Daniel Coats delivered a worldwide threat assessment that identified it as a significant security risk.

https://unearthed.greenpeace.org/2017/02/16/william-happer-trump-science-advisor/

---------------------------

Greenpeace Exposes Sceptics Hired to Cast Doubt on Climate Science
https://www.theguardian.com/environment/2015/dec/08/greenpeace-exposes-sceptics-cast-doubt-climate-science

Sting operation uncovers two prominent climate sceptics available for hire by the hour to write reports on the benefits of rising CO2 levels and coal

---------------------------

https://www.desmogblog.com/william-happer

Quote
In a 2015 undercover investigation by Greenpeace, Happer told Greenpeace reporters that he would be willing to produce research promoting the benefits of carbon dioxide for $250 per hour, while the funding sources could be similarly concealed by routing them through the CO2 Coalition. [8]
https://www.ecowatch.com/busted-academics-for-hire-exposed-for-failing-to-disclose-fossil-fuel--1882129109.html

In March 2018, Happer—among other , was asked by a judge to disclose any ties he had to fossil fuel companies in a case between cities and fossil fuel companies. Happer disclosed $1,000 he had received for a speech on climate change at the Heritage Foundation in 2017. The response to the request for information also revealed that Happer had received “around $10,000 to $15,000 though he does not recall the precise number” (emphasis added) from Peabody Coal, which was donated to the CO2 coalition on his behalf “earned in connection with testimony given in a Proceeding of the Minnesota Public Utilities Commission in September 2015.” [100], [101]

----------------------------------

Princeton Professor William Happer laid out details of an unofficial peer review process run by the Global Warming Policy Foundation (GWPF), a UK climate skeptic think tank and said he could ask to put an oil funded report through a similar review process, after admitting that it would struggle to be published in an academic journal.

https://unearthed.greenpeace.org/2015/12/08/exposed-academics-for-hire/


47
Trump believes Putin over those guys.

48
Related ...

Intel Chiefs Challenge Trump's National Security Claims
https://www.dni.gov/files/ODNI/documents/2019-ATA-SFR---SSCI.pdf



... Environment and Climate Change (pg 23)

Global environmental and ecological degradation, as well as climate change, are likely to fuel competition for resources, economic distress, and social discontent through 2019 and beyond.
Climate hazards such as extreme weather, higher temperatures, droughts, floods, wildfires, storms, sea level rise, soil degradation, and acidifying oceans are intensifying, threatening infrastructure, health, and water and food security. Irreversible damage to ecosystems and habitats will undermine the economic benefits they provide, worsened by air, soil, water, and marine pollution.

- Extreme weather events, many worsened by accelerating sea level rise, will particularly affect urban coastal areas in South Asia, Southeast Asia, and the Western Hemisphere. Damage to communication, energy, and transportation infrastructure could affect low-lying military bases, inflict economic costs, and cause human displacement and loss of life.

- Changes in the frequency and variability of heat waves, droughts, and floods—combined with poor governance practices—are increasing water and food insecurity around the world, increasing the risk of social unrest, migration, and interstate tension in countries such as Egypt, Ethiopia, Iraq, and Jordan.

- Diminishing Arctic sea ice may increase competition—particularly with Russia and China—over access to sea routes and natural resources. Nonetheless, Arctic states have maintained mostly positive cooperation in the region through the Arctic Council and other multilateral mechanisms, a trend we do not expect to change in the near term. Warmer temperatures and diminishing sea ice are reducing the high cost and risks of some commercial activities and are attracting new players to the resource-rich region. In 2018, the minimum sea ice extent in the Arctic was 25 percent below the 30-year average from 1980 to 2010.

....

- Migration is likely to continue to fuel social and interstate tensions globally, while drugs and transnational organized crime take a toll on US public health and safety. Political turbulence is rising in many regions as governance erodes and states confront growing public health and environmental threats.


Coats told lawmakers his opening remarks were intended "to provide you an overview of the national security threats facing our nation." He was the only one to give opening remarks, as he was speaking on behalf of those seated beside him: CIA Director Gina Haspel, FBI Director Christopher Wray, National Security Agency Director Gen. Paul Nakasone, Defense Intelligence Agency Director Gen. Robert Ashley and National Geospatial-Intelligence Agency Director Robert Cardillo.

"In many respects, it is a rebuke to the political rhetoric from the administration," John Cohen, a senior Homeland Security official focusing on threat-related intelligence under the Obama administration, and an ABC News contributor, said. "[It's] striking in some respects." ... "what is striking about this detailed assessment is what it doesn't say. ... The report does not reinforce or support recent claims by the administration of a national security crisis at the southern border,"

49
Extract: "... the researchers concluded that the excess oceanic heat is trapped in the Southern Ocean around the Antarctic."
Much of what ASLR posts is sobering (when I understand it).  This sentence suggests to me that Antarctic glaciers are doomed (not as if they weren't doomed previously), and like what ASLR regularly posts, there will be "more rapid climate change than expected by consensus climate science".

50
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...

Pages: [1] 2 3 ... 7