New paper by Steffen et al on Climate System Tipping Points

[CDN_dude]

https://www.sciencedaily.com/releases/2018/08/180806152040.htm

Paper is here, now open access https://doi.org/10.1073/pnas.1810141115

The team considered ten feedbacks--"permafrost thaw, loss of methane hydrates from the ocean floor, weakening land and ocean carbon sinks, increasing bacterial respiration in the oceans, Amazon rainforest dieback, boreal forest dieback, reduction of northern hemisphere snow cover, loss of Arctic summer sea ice, and reduction of Antarctic sea ice and polar ice sheets"--and found that even if human emissions only push the temperature up to 2 C, the feedbacks could still push the global temp eventually up to 4-5 C, with sea levels eventually (doesn't say when) reaching 10-60 metres.

In other words, the tipping point for a runaway warming, Hothouse Earth may be as low as 2 C above pre-industrial when all feedback loops are taken into account. 

[Avalonian]

This was on the BBC front page this morning as well... briefly. At least awareness of these dire possibilities is starting to reach the mainstream, even if it's rapidly displaced by politicians choosing unfortunate wording.
https://www.bbc.co.uk/news/science-environment-45084144

I can't say I'm at all surprised by this, anyhow; there are so many feedbacks starting to become visible even now that it's hard to imagine that they'll magically stop when we reach 2C.

[bbr2314]

So they completely ignore the impact of increasing water vapor and albedo shifts/ freshwater hosing due to ice mass loss? This is useless and garbage without considering ^ and as 2018 shows snow cover is already increasing (in fact Greenland has seen almost no decline in SMB this summer).

[Sam]

One aspect that is commonly missed in modeling is just how many of these non-linear complex systems behave in response to inputs. At times, these complex systems behave as "stiff" systems.

In the world of engineering these come up from time to time. They are not anomalies.

Such systems show variability, but they also accumulate inputs and show long delays to impacts from these inputs. Once the impacts reveal themselves it is far to late to do anything to avoid calamity. The new input adjustments take as long to show impact as the original inputs did. And when they do finally have impact, it is against a system that may be in a wholly different state than when the input was made.

Systems like that have to be handled with great care. They can easily go completely haywire.

Whether the Earth's biosphere and climate are stiff is as yet unknown. The previous sudden state changes may be an indicator of that. Or they may simply be an indicator of highly sensitive tipping points and strong interacting positive feedback loops.

I doubt we will know or learn the answers to these questions in any of our lifetimes.

At the same time, most people and most decision makers think in simple linear terms with extremely short attention spans approximating the attention spans of goldfish.

You cannot understand, let alone deal with, something complex like the Earth's climate thinking in short term linear fashion with an exponential driving function (population) and have any chance at all of success.

Instead, the system will control itself. And like so many biological systems without top level predators to act as a drag or brake on the system, the human population will likely go through boom and bust just like other species.

Unfortunately, our impacts are so immense on all of the Earth's systems, that we appear set to crash the entire set of interlocking systems taking the vast majority of species to extinction.

The new paper is useful, but even with the superposition of the various feedbacks they identify, they seem not to be looking at the interactive impact of these.  i.e. They are not simply linearly additive. The combined impact is vastly more than a linear sum of parts.

Fortunately, based on geologic evidence, there appears to be an upper bound condition and limit on temperature. Unfortunately, that world is so unlike the one we live in now as to be almost literally unthinkable. Even more unfortunately, the transition from our current state to that state is neither smooth, regular, predictable, nor assuredly survivable for civilization or agriculture - at least during the multiple century long transition.

Some limited evidence about the trajectory of the transition suggests severe changes in atmospheric oxygen levels and pressures, starting with such low oxygen levels that large animals may not be able to survive. Hint: humans are large animals.

[Sam]

In addition to this new paper, New Yorker Magazine has a full issue on climate change and the decade we had a chance to do something about it. Losing Earth.

https://www.nytimes.com/interactive/2018/08/01/magazine/climate-change-losing-earth.html?hp&#epilogue

[bbr2314]

In addition to this new paper, New Yorker Magazine has a full issue on climate change and the decade we had a chance to do something about it. Losing Earth.

https://www.nytimes.com/interactive/2018/08/01/magazine/climate-change-losing-earth.html?hp&#epilogue

Wonder how much carbon has been wasted in printing the New Yorker and how much conspicuous consumption has been induced by the advertising within... a total joke

[SteveMDFP]

In addition to this new paper, New Yorker Magazine has a full issue on climate change and the decade we had a chance to do something about it. Losing Earth.

https://www.nytimes.com/interactive/2018/08/01/magazine/climate-change-losing-earth.html?hp&#epilogue

Wonder how much carbon has been wasted in printing the New Yorker and how much conspicuous consumption has been induced by the advertising within... a total joke

NYT Magazine, actually.  It's a good article.  My copy came to me with less CO2 emissions than my own breathing, advertising included.  I didn't purchase anything.  Definitely not a waste of CO2 emissions.

[bbr2314]

In addition to this new paper, New Yorker Magazine has a full issue on climate change and the decade we had a chance to do something about it. Losing Earth.

https://www.nytimes.com/interactive/2018/08/01/magazine/climate-change-losing-earth.html?hp&#epilogue

Wonder how much carbon has been wasted in printing the New Yorker and how much conspicuous consumption has been induced by the advertising within... a total joke

NYT Magazine, actually.  It's a good article.  My copy came to me with less CO2 emissions than my own breathing, advertising included.  I didn't purchase anything.  Definitely not a waste of CO2 emissions.

Advertising doesn't work that way but good for you for consuming carbon-wasting paper media

[sark]

In addition to this new paper, New Yorker Magazine has a full issue on climate change and the decade we had a chance to do something about it. Losing Earth.

https://www.nytimes.com/interactive/2018/08/01/magazine/climate-change-losing-earth.html?hp&#epilogue

Wonder how much carbon has been wasted in printing the New Yorker and how much conspicuous consumption has been induced by the advertising within... a total joke

NYT Magazine, actually.  It's a good article.  My copy came to me with less CO2 emissions than my own breathing, advertising included.  I didn't purchase anything.  Definitely not a waste of CO2 emissions.

I would note that CO2 exhalation is not an addition of 'new carbon', despite the CO2 emissions of the tractors and trucks and processing that were applied to the food.  Measuring your carbon footprint should take into account the CO2 from fossil fuels and concrete expended to deliver the food, to the land use changes, methane outputs, and even from the extraction and use of oil as a feedstock for fertilizer, but not to the CO2 you exhale as a result of eating it.  Exhaling CO2 is not a part of your carbon footprint unless you literally eat fossil fuels.

I know this because I estimated the CO2 emissions of my own strenuous lifestyle and found it to be nearly 1 tonne per annum alone, and I'm trying to get below 2 tonnes.  Well, if you think it through, I'm not actually eating oil or coal so it can't count.

As someone who is struggling so hard to live within a globally equal distributed carbon budget, I don't care for appeals to morality.  It is reminiscent of a concern troll.  This has been aimed at me endlessly, with comments such as "how much CO2 was emitted by posting your comment?"

It's just physics.  We humans may be a quasi-sentient animal who require placement of data within a narrative in order to consider it, but our quasi-sentience is good enough to be objective enough, using rigor and honesty.  The fact is, it's an *extremely* difficult task to reduce your CO2 footprint to a level that falls within a carbon budget.

We're just barely scratching the surface of that fact as a civilization.  People are starting to get scared, and they're going to be looking for answers in droves, very soon.  Ideas about the morality of consumption are useless to me.  It doesn't matter how much you consume, destroy, waste, mark, and step on this planet.  It only matters how much greenhouse gasses are added to the atmosphere.

Right now there is virtually no space in a wealthy nation between a high carbon footprint and abject poverty.  This will change.  If enough people demand a lifestyle of low/zero carbon footprint, markets will be created, local food production will expand, and legal frameworks will be enacted that give a pathway to carbon neutrality to anyone who chooses it.

Today, don't feel bad for buying a magazine.  It's the water we swim in.  I prefer you using CO2 right now and figuring out how we're going to be carbon neutral by 2050.  Whatever you do to mitigate your emissions is welcome, but there's only so much you can give up before you remove your own power to be an investigator or advocate.

And don't ever feel bad about exhaling CO2, because that doesn't count.

[GeoffBeacon]

Avalonian

This was on the BBC front page this morning as well... briefly. At least awareness of these dire possibilities is starting to reach the mainstream, even if it's rapidly displaced by politicians choosing unfortunate wording.

Yes, the BBC downgraded 'Hothouse Earth' piece  by moving it to the back pages quite quickly.

On the BBC Six O'clock News today Zeb Sones and Richard Shukman were saying this (At about 16m30s):

Zeb Soanes:
The scientific community has reacted cautiously to a new study which warns that the world is at risk from dangerous levels of climate change the could make some areas of the planet uninhabitable. The paper by a team at the University of Stockholm predicts that as global warming gathers pace it will become impossible to control but while many other researchers acknowledge the threat posed they say the predictions in this latest report a very much a worst case scenario our science editor David Shukman has been weighing up the arguments.

David Shukman:
At a time of multiple heat waves from California to Britain to Japan an apocalyptic vision of an overheated future, what's called a hothouse Earth has caught the imagination. The scientists argue that natural features of the planet help to keep it cool. The oceans and the forests absorb much of the carbon dioxide released by cars, factories and power stations and without them the gas would into the atmosphere and raise temperatures further but it's  suggested if there's damage to these natural buffers a series of dominoes would suddenly fall. The frozen soils in the arctic releasing methane, the melting of the ice sheets accellerating, weather patterns shifting and whole region becoming hostile to life. So how plausible is this?

Individually each of these processes is physically possible but taken together the idea of a cascade of impacts triggering runaway warming is more extreme than many other studies of climate change. It goes far beyond the carefully drafted assessments of the United Nations.

Privately some scientists not involved in the study regard it as speculative - technically feasible but much less likely the more established forcasts for the future climate. Even so, many in the field say the research is a reminder that the planet is definitely getting hotter than that urgent action to cut the gas is the course of warming is needed to limit the damage.

"some scientists" ? Any guesses?

[Bruce Steele]

The New York Times article timeline perspective on our collective failure to act is a good job of journalism IMO. Makes me think back to when I had  my moment of realization...this is bad, real bad. For me it was 2005 and it came in the form of the first paper about subjecting biological specimens to acidified seawater. Shiryama et al 2005 . My wife got an education along with me because acidification and climate change is a big damn subject .We are both involved with fisheries and fisheries politics and we have struggled together to rise the awareness at least in the political circles we have some affect upon.
 Getting from the moment of realization to making some waves politically has taken long enough that the commensurate lifestyle changes we could personally take have developed as a corrolary. So my wife has struggled along with me , taken the "acorn challenge" , invested in solar and quit almost all air travel.
 Fisheries have only lately begun to look into adaptation . I don't think that is an adequate response so I am pushing for something more like adapting fisheries management to consider mechanisms to favor efficiency. It is where we will end up anyhow so operating fisheries utilizing less fuel for calories produced is where I am focusing.
 Politics is always disappointing but it is part of what I consider necessary pain. And posting here is mostly cathartic. Politics for the authors of the two articles cited above and most of the characters involved has also been painful I am sure . It isn't heroics , it's hard work .
 

[gerontocrat]

In addition to this new paper, New Yorker Magazine has a full issue on climate change and the decade we had a chance to do something about it. Losing Earth.

https://www.nytimes.com/interactive/2018/08/01/magazine/climate-change-losing-earth.html?hp&#epilogue

Wonder how much carbon has been wasted in printing the New Yorker and how much conspicuous consumption has been induced by the advertising within... a total joke

NYT Magazine, actually.  It's a good article.  My copy came to me with less CO2 emissions than my own breathing, advertising included.  I didn't purchase anything.  Definitely not a waste of CO2 emissions.

Advertising doesn't work that way but good for you for consuming carbon-wasting paper media

The server that manages this forum consumes a lot of power, (still mostly produced by fossil fuels?)

Anyway, mealy-mouthed comments are hardly a great contribution as to the worth or otherwise of the paper. I found it useful, a reminder that AGW has many strands - not just CO2 emissions.

And I love books - the ones you hold in your hand instead of a piece of plastic and electronics called a kindle.

And - how the hell will the Public at large get exposed to the issues raised and considered in this forum without the help of the mainstream media ?

[bbr2314]

In addition to this new paper, New Yorker Magazine has a full issue on climate change and the decade we had a chance to do something about it. Losing Earth.

https://www.nytimes.com/interactive/2018/08/01/magazine/climate-change-losing-earth.html?hp&#epilogue

Wonder how much carbon has been wasted in printing the New Yorker and how much conspicuous consumption has been induced by the advertising within... a total joke

NYT Magazine, actually.  It's a good article.  My copy came to me with less CO2 emissions than my own breathing, advertising included.  I didn't purchase anything.  Definitely not a waste of CO2 emissions.

Advertising doesn't work that way but good for you for consuming carbon-wasting paper media

The server that manages this forum consumes a lot of power, (still mostly produced by fossil fuels?)

Anyway, mealy-mouthed comments are hardly a great contribution as to the worth or otherwise of the paper. I found it useful, a reminder that AGW has many strands - not just CO2 emissions.

And I love books - the ones you hold in your hand instead of a piece of plastic and electronics called a kindle.

And - how the hell will the Public at large get exposed to the issues raised and considered in this forum without the help of the mainstream media ?

I think it's better the public has no idea what is actually happening? The only way that consumerism can be controlled is through state action, the public will never give up their materialism willingly, consumerism is the opiate of the masses. I would actually bet a decent number of government officials read this forum and that is where action will be had, not in Midwestern people who refuse to give up SUVs or people in China entering the middle class, who are never going to give up their newfound wealth willingly.

If the public knew that the situation was far worse than what the media is saying, there would either be panic or inaction, it would make no difference IMO.

[Bruce Steele]

Bbr2314  Treating people like they're idiots and suggesting strongarm state government actions will get you more Donald Trump . Do you ever go stand up in public meetings or participate in public forums where you don't get to hide behind anonymity?

[bbr2314]

Bbr2314  Treating people like they're idiots and suggesting strongarm state government actions will get you more Donald Trump . Do you ever go stand up in public meetings or participate in public forums where you don't get to hide behind anonymity?

Technically Trump's tariffs will do more to reduce consumerism and emissions than any policies enacted by his predecessors, with the "trade war" set to boost costs of consumer goods from North America, to Asia, to Europe... while this is "bad" for consumers it is good for the environment (although many of his other policies are decidedly unfriendly to the environment, this is probably more impactful, since consumption is the root cause of the current crisis).

Also public meetings do not result in positive change, tyranny of a vocal minority usually overwhelms sensible discourse. I write about weather etc in real life on occasion too, not under a pseudonym, in fact this is probably the only forum I participate in where I am "anonymous".

[Bruce Steele]

Bbr2214 , Maybe the effort it takes to make hundreds of meetings about agriculture, water or fisheries issues...(politics in general) leads me to a different opinion about positive change or the effectiveness
? Tyranny ? of the vocal minority. Getting out there in the public and making your little stand is important ,  I gotta believe that.
 The authors of both of the cited articles are taking a bit of a beating.  I think people should have some idea about how bad things may get so I am happy they stood up.
 For what it's worth I took a very vocal stand about ocean acidification over ten years ago. For a commercial fisherman I was way out in front of a very new issue. Acidification in the intervening decade has become much clearer in the threat category. A fisherman friend recently admitted he thought I was nuts ten years ago but he now wonders how much damage we are in for or maybe already seeing.
 I would like to give you a story about how the new 52% tariff on squid is impacting Calif. sales to China but everything is in such flux that I don't have much to say. Tariff was 27% and another 25% has been added.
 
 
 

[Capt Kiwi]

Avalonian

David Shukman:
 It goes far beyond the carefully drafted assessments of the United Nations.

Whew, that’s a relief! Guess we’ll be fine then! 

[Richard Rathbone]

Anyone else read this paper and think the numbers don't add up? It looks like a bunch of handwaving and pretty pictures to me. There ought to be 2 (of actual warming) + 2 (of committed feedbacks) = 4 somewhere in it to back up the claims they make, but the table of committed feedbacks doesn't come close to 2.

[Pmt111500]

I haven't read the article yet, but had to say to a friend "that's certainly possible with the help of modern technology". Given that in my opinion stopping the rise at +4 C could be possible, like starting now, idk why the authors include effects that would, AFAIK, occur at +6-8°C (another point to stop). Of course, it's technically possible to get to at least +12 degrees C which would certainly cover all the effects reported. But imo it's a good thing the unmitigated effects have been put on paper. And the tipping of natural sinks to emitters is a subject of study nowadys.

[Pmt111500]

Almost forgot to add, is this it?

[gerontocrat]

Almost forgot to add, is this it?

Nice one, Pmt111500

Yes it is, someone broke the paywall or a subscriber to the journal just casually sent their copy into cyberspace.

[CDN_dude]

It's since been made open-access

[AbruptSLR]

So they completely ignore the impact of increasing water vapor and albedo shifts/ freshwater hosing due to ice mass loss? This is useless and garbage without considering ^ and as 2018 shows snow cover is already increasing (in fact Greenland has seen almost no decline in SMB this summer).

While this paper errs on the side of least drama by ignoring, and/or under-representing, numerous potential positive feedback mechanisms; I would not say that this paper is 'garbage'; unless one plans to take its findings as a final and definitive projection, instead of as an improved Bayesian posterior for a less accurate prior.

My point is that consensus climate science is slowly moving towards more accurate projections; which is good, even if their slow rate of improvement means that society will not receive adequate warning to prevent abrupt climate change this century.

Edit: I note that increased snow fall in the catchment basins of both Greenland marine terminating glaciers, and Antarctic marine glaciers, serves to increase the rate of calving from such marine glaciers; which increases the probability of abrupt climate change from Hansen's ice-climate feedback mechanism this century.

[bluesky]

I haven't read the article yet, but had to say to a friend "that's certainly possible with the help of modern technology". Given that in my opinion stopping the rise at +4 C could be possible, like starting now, idk why the authors include effects that would, AFAIK, occur at +6-8°C (another point to stop). Of course, it's technically possible to get to at least +12 degrees C which would certainly cover all the effects reported. But imo it's a good thing the unmitigated effects have been put on paper. And the tipping of natural sinks to emitters is a subject of study nowadys.

Not really sure how stabilizing the rise at 4°C would be possible unless using extensive, unworkable and uneconomical geo engineering that would have dire side effect?

[bluesky]

So they completely ignore the impact of increasing water vapor and albedo shifts/ freshwater hosing due to ice mass loss? This is useless and garbage without considering ^ and as 2018 shows snow cover is already increasing (in fact Greenland has seen almost no decline in SMB this summer).

While this paper errs on the side of least drama by ignoring, and/or under-representing, numerous potential positive feedback mechanisms; I would not say that this paper is 'garbage'; unless one plans to take its findings as a final and definitive projection, instead of as an improved Bayesian posterior for a less accurate prior.

My point is that consensus climate science is slowly moving towards more accurate projections; which is good, even if their slow rate of improvement means that society will not receive adequate warning to prevent abrupt climate change this century.

Edit: I note that increased snow fall in the catchment basins of both Greenland marine terminating glaciers, and Antarctic marine glaciers, serves to increase the rate of calving from such marine glaciers; which increases the probability of abrupt climate change from Hansen's ice-climate feedback mechanism this century.

Completely agree with you AbruptSLR, however, I think this article has some very good positive sides:

-this is a holistic, analytical paper, very well articulated and making the link between many previous  specialised research papers on each of the potential tipping points and many others.
-this kind of analytical, rational and holistic paper is really missing in the climate change littérature, except for the IPCC report, which as everybody knows, is plagued with too much conservatism and always lagging behind the latest research, and /or simply ignore some of them (obviously for the latest one, the alarming increasing rate of melting of WAIS/ Amundsen Bay and some of the EAIS to a lesser extent for assessing SLR)
-there are some cautious approaches in this paper, but this is probably the first time that a team of well respected international scientists warns that even 2° C warming may not be safe and may trigger unstoppable feedback processes, and
-this is very well articulated, pretty easy to read, and to understand, every body should read it in its entirety.
-the supporting material is also an excellent synthesis of the present warming in relation to previous warming and should be a must read, for anyone who still has not got a broad view of this current warming in relation to any previous paleo climatic warming event.

-the supporting material is completed with a series of excellent synthetic table giving a real grasp of interrelations between:
   1/biogeophysical feedbacks in the earth system that could accelerate the trajectory towards "hot house"
   2/carbon stored in main biomes
   3/ critical biosphere or Earth systems that support humanity
   4/human actions that could steer the Earth system onto a "stabilised Earth trajectory"
       a/ enhancing or creating negative feedbacks through carbon sinks
       b/ reducing greenhouse gas emission from fossil fuels and other sources
       c/modifying Earth's energy balance
       d/fundamental changes in society

d/ include "changes in consumer behaviors" and I presume this is one of the reasons, including the underlying risk of a 2 °C warming , that some media brand this paper as almost extreme!!!

-this paper is one of the very rare, openly advocating that a very deep serious change in the way our society work is one of the key stone to avoid run away climate change...

My main regret is that the main paper suggests that some type of geo engineering may have to be used while the supplementary material warns that geo engineering is , at present stage, un economical, still mostly at R&D stage, and may trigger dire side effects, this should have been stated in the main paper.

Finally, the fact that this paper could be stained as an " alarmist outlier view" by the BBC (and some scientists?), and that most on the climate scientist community and the ASIF members would consider it as an unsuprising paper, even with some light touch of conservatism, shows the dire and deep knowledge gap between the wide public and the scientific community is not filling with time, but widening...
That's why this paper is very welcome and should be spread, explained and supported. Good youtube video would be welcome.




   


        -

[bluesky]

here is the link to the supporting information, a must read:

http://www.pnas.org/content/pnas/suppl/2018/07/31/1810141115.DCSupplemental/pnas.1810141115.sapp.pdf

[Pmt111500]

I haven't read the article yet, but had to say to a friend "that's certainly possible with the help of modern technology". Given that in my opinion stopping the rise at +4 C could be possible, like starting now, idk why the authors include effects that would, AFAIK, occur at +6-8°C (another point to stop). Of course, it's technically possible to get to at least +12 degrees C which would certainly cover all the effects reported. But imo it's a good thing the unmitigated effects have been put on paper. And the tipping of natural sinks to emitters is a subject of study nowadys.

Not really sure how stabilizing the rise at 4°C would be possible unless using extensive, unworkable and uneconomical geo engineering that would have dire side effect?

There's a prehistorical precedent from pliocene/oligocene that earth can stay at this level without humans, how to cut off most of the cascades presented in the article (now I've read it) requires quite a lot I admit.

[bluesky]

but yes, some of the temperature threshold for triggering the tipping points, maybe considered a bit conservative (AMOC cooling at 3°C and jet stream at 3°C, are we close or already at the tipping point due to Greenland and Arctic sea ice melting?) while permafrost at 5°C seems conservative. Ocean acidification is missing as a related tipping point to coral bleeching together with sea warming, and the reduction of carbon intake from the ocean is also missing. What about the unknown tipping points?
Also, a big unknown is the cascading effect on seemingly non related tipping point through atmospheric or ocean circulation/ teleconnection...
I won't argue on winter sea ice at 3 to 5 °C of warming, the threshold seems extremely difficult to assess and would require a complete change in water column and current in the Arctic ocean, mainly in the depth of central Arctic (another thread...)

[bluesky]

I haven't read the article yet, but had to say to a friend "that's certainly possible with the help of modern technology". Given that in my opinion stopping the rise at +4 C could be possible, like starting now, idk why the authors include effects that would, AFAIK, occur at +6-8°C (another point to stop). Of course, it's technically possible to get to at least +12 degrees C which would certainly cover all the effects reported. But imo it's a good thing the unmitigated effects have been put on paper. And the tipping of natural sinks to emitters is a subject of study nowadys.

Not really sure how stabilizing the rise at 4°C would be possible unless using extensive, unworkable and uneconomical geo engineering that would have dire side effect?

There's a prehistorical precedent from pliocene/oligocene that earth can stay at this level without humans, how to cut off most of the cascades presented in the article (now I've read it) requires quite a lot I admit.

I presume this paleo climatic event was in a different set up regarding orbital forcing, long term cooling of the planet, carbon emission, even possibly the continental shape and geographical location (?), the positive and the negative feedback were probably neutralising altogether. As James Hansen often remind us, we are doing a unique experiment (increasing the CO2 content  in the atmosphere at the highest speed for the past 66 million years…), this is also reminded in the supplementary document of Will Steffen et al' s paper, so comparing with previous paleo climatic event always require a degree of caution

[mitch]

The fundamental difference between the Pleistocene and the rest of the Cenozoic is that deep waters are 3-10 degC warmer before 3 million years ago. The huge heat reservoir of the deep ocean meant that heat brought up from below ended the smaller cold perturbations. Right now the deep ocean is at a cold extreme, which helps to ameliorate warm perturbations. 

Between the deep ocean and the remaining ice sheets, it is harder to push warming  despite the energy imbalance, sort of like walking up hill rather than on a flat surface.

[Pmt111500]

The fundamental difference between the Pleistocene and the rest of the Cenozoic is that deep waters are 3-10 degC warmer before 3 million years ago. The huge heat reservoir of the deep ocean meant that heat brought up from below ended the smaller cold perturbations. Right now the deep ocean is at a cold extreme, which helps to ameliorate warm perturbations. 

Between the deep ocean and the remaining ice sheets, it is harder to push warming  despite the energy imbalance, sort of like walking up hill rather than on a flat surface.

I thought i said that already... On a post some 5 years ago

[AbruptSLR]

The fundamental difference between the Pleistocene and the rest of the Cenozoic is that deep waters are 3-10 degC warmer before 3 million years ago. The huge heat reservoir of the deep ocean meant that heat brought up from below ended the smaller cold perturbations. Right now the deep ocean is at a cold extreme, which helps to ameliorate warm perturbations. 

Between the deep ocean and the remaining ice sheets, it is harder to push warming  despite the energy imbalance, sort of like walking up hill rather than on a flat surface.

I thought i said that already... On a post some 5 years ago

What a coincidence, some 5 years ago in numerous posts in the "Supporting Paleo-Evidence/Calibration for WAIS Collapse Hazard Scenarios" thread, I noted how repeatedly in the paleo-recorder the collapse of the WAIS has triggered 'Super-Interglacial' events with very high values of both ECS and ESS.

https://forum.arctic-sea-ice.net/index.php/topic,130.0.html

In this regards, I reiterate that per Pollard and DeConto 2016, the WAIS will likely enter a phase of abrupt ice mass loss due to cliff failures and hydrofracturing well before GMSTA reaches 2.7C.  If this happens, Hansen et al. (2016), see the first attached image, calculate a multi-decade long spike in the imbalance of planetary radiative forcing, which could ratchet the Earth's climate sensitivity rapidly to a higher level (see the second two images); which could accelerate numerous positive feedbacks pushing ECS rapidly upwards towards the 6C value for ESS that Hansen et al (2008) calculate for the Pleistocene (last 400,000 years), per the fourth image.

[AbruptSLR]

As a follow on to my last post.  Friedrich et al 2016 calibrated a modern model to the paleo-record for the past 784,000 years (see the first image), and they found that GMSTA could be over 7C by 2100 assuming a BAU pathway (see the second image).  This research confirms that values of ECS could increase rapidly this century (see the third image); which the fourth image, illustrates how 'noise' in the planetary radiative forcing imbalance (say due to a collapse of the WAIS together with Hansen's ice-climate feedback mechanism) could abruptly push ECS up into a higher sensitivity state, due to saddle-node bifuraction.

[jai mitchell]

missing an arrow from  ENSO to boreal forest

https://www.bbc.com/news/science-environment-36212145

'Perfect storm' of El Niño and warming boosted Alberta fires



this just shows that even in the studies about these interactive tipping points, the comprehensive knowledge of these complex and varied systems is pathetically weak in the body of professional climate scientists. 

If the entire AGU was focused only on these things for a year then we might have a comprehensive knowledge of the entire level of sticky problem interactive effects.  However, the desire for some kind of consensus without uncertainty would prevent the adoption of the most likely reality.

We have been doing work on these interactive tipping points (and more) here:  https://forum.arctic-sea-ice.net/index.php/topic,1053.0.html

[AbruptSLR]

As a follow-on to my last two posts, I provide,

1. The first image, shows how DeConto & Pollard (2016) calculate how the WAIS could abruptly collapse when GMSTA is somewhere between 2C and 2.7C.

2. The second image, shows how Andrew (2015) projects how a slow down of the ocean conveyor belt can build-up SSTA in the Equatorial Pacific (as projected by Hansen's ice-climate feedback mechanism); which could rapidly drive ECS up to 5C.

3. The third image, shows how a build-up of SSTA in the Equatorial Pacific can rapidly/atmospherically telecommunication heat from the tropics to the Arctic, thus rapidly increasing Arctic Amplification.

4.  The fourth image shows how per Sherwood 2014, a build-up of SSTA in the Equatorial Pacific can rapidly increase deep atmospheric convective circulation; which rapidly increase high cloud cover; which rapidly increases ECS due to positive cloud feedback.

These all illustrate how a rapid loss of the WAIS could rapidly increase ECS this century.

[jai mitchell]

In the 2012 paleosens paper on 800 kya historic climate sensitivity, they provided data only for periods during glacial lock-in, the interglacial period showed values of S that were so much higher that it practically blew up there models (see image below).

https://websites.pmc.ucsc.edu/~jzachos/pubs/Rohling_etal_2012.pdf

Even though they provided this extreme conservatism, by removing data points that best fit our current climate conditions, even so, when they attached future climate response, they attached a best-fit linear average value to the non-linear glacial period value.

So their results for future sensitivity were doubly conservative and (we now know) severely understated future climate response.

[AbruptSLR]

If the entire AGU was focused only on these things for a year then we might have a comprehensive knowledge of the entire level of sticky problem interactive effects.  However, the desire for some kind of consensus without uncertainty would prevent the adoption of the most likely reality.

The DOE has recently released computer code & preliminary results from ACME (Accelerated Climate Model for Energy) while the DOE has renamed the program E3SM (Energy Exascale Earth System Model), and this world's most sophisticated climate model projects that ECS for the rest of this century will be about 5.2C (& this relatively high value is likely attributable to the state-of-the-art way that ACME/E3SM models aerosols and cloud feedback mechanisms).

While some consensus scientists (like Bjorn Stevens) have said that it is difficult to determine whether the ACME findings are any more relevant than other models in the CMIP6 program; I believe that these findings from the world's most advanced ESM warrant the adoptions of the Precautionary Principle, particularly as the ACME results only partially address Hansen's ice-climate feedback mechanism:

Title: "DOE’s maverick climate model is about to get its first test"
doi:10.1126/science.aau0578

http://www.sciencemag.org/news/2018/05/does-maverick-climate-model-about-get-its-first-test

Extract: "In 2017, after President Donald Trump took office and pulled the nation out of the Paris climate accords, DOE dropped "climate" from the project name. The new name, the Energy Exascale Earth System Model (E3SM), better reflects the model's focus on the entire Earth system, says project leader David Bader of Lawrence Livermore National Laboratory in California.
..
One preliminary result, on the climate's sensitivity to carbon dioxide (CO2), will "raise some eyebrows," Bader says. Most models estimate that, for a doubling of CO2 above preindustrial levels, average global temperatures will rise between 1.5°C and 4.5°C. The E3SM predicts a strikingly high rise of 5.2°C, which Leung suspects is due to the way the model handles aerosols and clouds. And like many models, the E3SM produces two bands of rainfall in the tropics, rather than the one seen in nature near the equator.

The first test of the E3SM will be its performance in CMIP6. Nearly three dozen modeling groups, including newcomers from South Korea, India, Brazil, and South Africa, are expected to submit results to the intercomparison between now and 2020."

See also:

https://gcn.com/articles/2018/04/26/e3sm-earth-model.aspx

&

https://www.llnl.gov/news/new-exascale-system-earth-simulation

[bluesky]

Avalonian

This was on the BBC front page this morning as well... briefly. At least awareness of these dire possibilities is starting to reach the mainstream, even if it's rapidly displaced by politicians choosing unfortunate wording.

Yes, the BBC downgraded 'Hothouse Earth' piece  by moving it to the back pages quite quickly.

On the BBC Six O'clock News today Zeb Sones and Richard Shukman were saying this (At about 16m30s):

Zeb Soanes:
The scientific community has reacted cautiously to a new study which warns that the world is at risk from dangerous levels of climate change the could make some areas of the planet uninhabitable. The paper by a team at the University of Stockholm predicts that as global warming gathers pace it will become impossible to control but while many other researchers acknowledge the threat posed they say the predictions in this latest report a very much a worst case scenario our science editor David Shukman has been weighing up the arguments.

David Shukman:
At a time of multiple heat waves from California to Britain to Japan an apocalyptic vision of an overheated future, what's called a hothouse Earth has caught the imagination. The scientists argue that natural features of the planet help to keep it cool. The oceans and the forests absorb much of the carbon dioxide released by cars, factories and power stations and without them the gas would into the atmosphere and raise temperatures further but it's  suggested if there's damage to these natural buffers a series of dominoes would suddenly fall. The frozen soils in the arctic releasing methane, the melting of the ice sheets accellerating, weather patterns shifting and whole region becoming hostile to life. So how plausible is this?

Individually each of these processes is physically possible but taken together the idea of a cascade of impacts triggering runaway warming is more extreme than many other studies of climate change. It goes far beyond the carefully drafted assessments of the United Nations.

Privately some scientists not involved in the study regard it as speculative - technically feasible but much less likely the more established forcasts for the future climate. Even so, many in the field say the research is a reminder that the planet is definitely getting hotter than that urgent action to cut the gas is the course of warming is needed to limit the damage.

"some scientists" ? Any guesses?

Three high ranked scientists feedbacks, one seems to be clearly on the conservative side:

http://www.sciencemediacentre.org/expert-reaction-to-perspective-piece-on-the-trajectories-of-the-earth-system/

[bluesky]

Paul Beckwith presentation of the appendix from 3m 27 onward:

[Pmt111500]

Thanks bluesky for the presentation, mid-pliocene like result from this worldwide experiment still sounds a possible outcome. Road there isn't too pretty, though.

[bluesky]

A new paper, to advise policymakers of the urgency to act on climate matters has been released, scientists are from Oxford and Utrecht Uni, they ran  a stochastic modelled based on CMIP5 to calculate the year of the Point of No Return (PNR) for limiting climate warming to 1.5°C or 2°C based on various confidence levels:

“In our study we show that there are strict deadlines for taking climate action,” says Henk Dijkstra, a professor at Utrecht University in the Netherlands and one of the study authors. “We conclude that very little time is left before the Paris targets [to limit global warming to 1.5°C or 2°C] become infeasible even given drastic emission reduction strategies.” (from EGU website)

"Using information from climate models, the team determined the deadline for starting climate action to keep global warming likely (with a probability of 67%) below 2°C in 2100, depending on how fast humanity can reduce emissions by using more renewable energy. Assuming we could increase the share of renewable energy by 2% every year, we would have to start doing so before 2035 (the point of no return). If we were to reduce emissions at a faster rate, by increasing the share of renewable energy by 5% each year, we would buy another 10 years.
The researchers caution, however, that even their more modest climate-action scenario is quite ambitious. “The share of renewable energy refers to the share of all energy consumed. This has risen over the course of over two decades from almost nothing in the late nineties to 3.6% in 2017 according to the BP Statistical Review, so the [yearly] increases in the share of renewables have been very small,” says Rick van der Ploeg, a professor of economics at Oxford University, who also took part in the Earth System Dynamics study. “Considering the slow speed of large-scale political and economic transformations, decisive action is still warranted as the modest-action scenario is a large change compared to current emission rates,” he adds.
To likely limit global warming to 1.5°C in 2100, humanity would have to take strong climate action much sooner. We would only have until 2027 to start if we could increase the share of renewables at a rate of 5% a year. We have already passed the point of no return for the more modest climate-action scenario where the share of renewables increases by 2% each year. In this scenario, unless we remove carbon dioxide from the atmosphere, it is no longer possible to achieve the 1.5°C target in 2100 with a probability of 67%.
Removing greenhouse gases from the atmosphere, by using ‘negative emissions’ technology, could buy us a bit more time, according to the study. But even with strong negative emissions, humanity would only be able to delay the point of no return by 6 to 10 years.
“We hope that ‘having a deadline’ may stimulate the sense of urgency to act for politicians and policy makers,” concludes Dijkstra. “Very little time is left to achieve the Paris targets.” (from EGU website)
https://www.egu.eu/news/428/deadline-for-climate-action-act-strongly-before-2035-to-keep-warming-below-2c/

Abstract:
 If the Paris Agreement targets are to be met, there may be very few years left for policy makers to start cutting emissions. Here we calculate by what year, at the latest, one has to take action to keep global warming below the 2K target (relative to pre-industrial levels) at the year 2100 with a 67% probability; we call this the point of no return(PNR).Usinganovel,stochasticmodelofCO2 concentration and global mean surface temperature derived from the CMIP5 ensemble simulations, we find that cumulative CO2 emissions from 2015 onwardsmaynotexceed424GtCandthatthePNRis2035forthepolicyscenariowheretheshareofrenewable energy rises by 2%year−1. Pushing this increase to 5%year−1 delays the PNR until 2045. For the 1.5K target, the carbon budget is only 198GtC and there is no time left before starting to increase the renewable share by 2%year−1. If the risk tolerance is tightened to 5%, the PNR is brought forward to 2022 for the 2K target and has been passed already for the 1.5K target. Including substantial negative emissions towards the end of the century delays the PNR from 2035 to 2042 for the 2K target and to 2026 for the 1.5K target.We thus show how the PNR is impacted not only by the temperature target and the speed by which emissions are cut but also by risk tolerance, climate uncertainties and the potential for negative emissions. Sensitivity studies show that the PNR is robust with uncertainties of at most a few years.


We'd better rush, considering that anyone in the Western world insures his house although the average probability of the house to be knock downed to rubble either by fire or by a geophysical hazard is far less than 5%...before the human kind pays the consequence of his foolish complacency of course!

Access to article:
https://www.earth-syst-dynam.net/9/1085/2018/esd-9-1085-2018.pdf

I have not read the article yet, simulation is based on a stochastic model derived from CMIP5, therefore the effect of non linear tipping points may be underestimated...and the PNR closer than the underlying calculation from the paper.

[Tom_Mazanec]

More on that article:
https://www.todayonline.com/heat-earth-getting-very-very-close-crossing-tipping-point-scientist-warns