Arctic Death Spiral: Sea Ice Passes De Facto Tipping Point Thanks to Deniers, Media Blow The Story, Again

Arctic sea ice volume by month in cubic kilometers. The bottom (black) line is September volume. The plot makes projections with simple quadratic trend lines (details here), which likely oversimplify matters as we approach zero volume (especially for non-summer months). But reversal of the overall death spiral is highly implausible absent an even more implausible reversal of current climate policies — policies which are promoted by denier disinformation and sustained by media stenography.

The Arctic is all but certain to be virtually ice free within two decades (barring extreme volcanic activity). I’m happy to make bets with any bloggers, like Andy Revkin, who apparently believe otherwise.

The recent scientific literature makes clear that while that death spiral could theoretically be reversed, it would require policies that climate science deniers have successfully demonized, policies many in the traditional media regularly pooh pooh or undercut.

So we have passed a de facto tipping point, “the critical point in an evolving situation that leads to a new and irreversible development.” If that wasn’t obvious from observations, then it should have been clear from a December study in Nature widely misunderstood by the media. That study showed sea ice extent crashing by two thirds by the 2030s and then collapsing to near-zero shortly thereafter — unless we cut global GHG emissions about 60% to 70% almost immediately and have further cuts after that, an implausible assumption the authors never spelled out clearly (as I explain here).

Now comes a new study that has also proven an irresistible source of confusion to both the deniers and the media, “A 10,000-Year Record of Arctic Ocean Sea-Ice Variability — View from the Beach” (subs. req’d). The news release is as misleading as the Nature article:

The bad news is that there is a clear connection between temperature and the amount of sea ice. And there is no doubt that continued global warming will lead to a reduction in the amount of summer sea ice in the Arctic Ocean. The good news is that even with a reduction to less than 50% of the current amount of sea ice the ice will not reach a point of no return: a level where the ice no longer can regenerate itself even if the climate was to return to cooler temperatures,” [lead author Svend] Funder says.

Huh? How precisely is the climate going to return to cooler temperatures? It really bugs me when scientists who are very sophisticated in one arena — here, proxy reconstructions of ice coverage of part of the Arctic — exhibit magical thinking in another area.

The best recent models show staggeringly high Arctic warming this century if we stay on our current emissions path (see M.I.T. doubles its 2095 warming projection to 10°F — with 866 ppm and Arctic warming of 20°F). Cooling ain’t in the cards. Quite the reverse.

The Nature article projected a 50% decline in sea ice within 2 decades no matter what we do on emissions — and then total collapse even on a scenario with significant emissions reductions. As an aside, since that study almost certainly underestimated the rate of sea ice loss — for instance, it ignores black carbon, a major source of ice loss — I tend to think that the actual summer ice loss will be somewhere between what that study projected and the oversimplified quadratic projections in the figure above.

The BBC, which promised better coverage on climate change, failed to deliver this time — as can be seen in its story, “Arctic ‘tipping point’ may not be reached.

NYT opinion blogger Andy Revkin wrote one of the worst pieces in his career, “On Arctic Ice and Warmth, Past and Future,” which quickly became a darling of the hard-core anti-science deniers for these absurd lines:

But even as I push for an energy quest that limits climate risk, I’m not worried about the resilience of Arctic ecosystems and not worried about the system tipping into an irreversibly slushy state on time scales relevant to today’s policy debates. This is one reason I don’t go for descriptions of the system being in a “death spiral.”

The main source of my Arctic comfort level — besides what I learned while camped with scientists on the North Pole sea ice — is the growing body of work on past variations* in sea ice conditions in the Arctic. The latest evidence comes in a study in the current issue of Science. The paper, combining evidence of driftwood accumulation and beach formation in northern Greenland with evidence of past sea-ice extent in parts of Canada, concludes that Arctic sea ice appears to have retreated far more in some spans since the end of the last ice age than it has in recent years.

“Not worried about the resilience of Arctic ecosystems”? Seriously?

Exactly what Arctic ecosystems are going to survive the accelerated warming humans are imposing, warming that will occur at twice the rate of the planet as a whole? And that is compounded by ocean acidification, which is equally devastating in the Arctic.

Revkin’s wishy-washy “energy quest” can’t stop either of those disasters. Indeed, Revkin never tells you what CO2 concentrations target he is questing for, but he endlessly criticizes those of us who actually spell out a target, like 450 ppm (or lower) and a path to achieve it. He dismisses such targets as a “magically safe level of carbon dioxide” — a reductio ad absurdum meant to put him above the fray, allowing him to critique all those trying to avert 800+ ppm — a CO2 level he once told me is where he expects we’ll end up.

Indeed in 2008, he himself quoted Nobelist Sherwood Rowland who thinks we’re headed toward 1000 ppm, an unimaginable catastrophe. Back then he wrote, “Keep in mind that various experts and groups have said risks of centuries of ecological and economic disruption rise with every step toward and beyond 450 parts per million.” Now, by failing to identify even a range we should aim for, say 400 to 500 ppm or policies that could plausibly keep us near such a range — and worse, by mocking those of us who do — he is effectively endorsing the acceptability of the 800 to 1000 ppm range.

The science is clear that human-caused Arctic warming has overtaken 2,000 years of natural cooling, as a “seminal” 2009 Science study found” [see figure below]:

In short, “greenhouse gas emissions are overwhelming the system,” as David Schneider, a visiting scientist at the National Center for Atmospheric Research and one of the co-authors of the 2009 Science article put it.

Oh, but Revkin says he’s “not worried about the system tipping into an irreversibly slushy state on time scales relevant to today’s policy debates.”

Well, NOAA and the National Snow and Ice Data Center (NSIDC) are worried, and unlike Revkin, they have published science to back them up — see NSIDC bombshell: Thawing permafrost feedback will turn Arctic from carbon sink to source in the 2020s, releasing 100 billion tons of carbon by 2100.

Figure: Carbon emission (in billions of tons of carbon a year) from thawing permafrost.

UPDATE: Revkin tries to claim that I’m “straying into discussions of melting permafrost” which he claims “is an entirely different issue.” But it isn’t. He is the one who wrote that he is “not worried about the system tipping into an irreversibly slushy state on time scales relevant to today’s policy debates.” The perma-melt NOAA/NSIDC is the “irreversibly slushy state.” I thought that was obvious.

I have little doubt that the drop in sea ice over the next 10 to 15 years will be a major driver of policy — now that the deniers, with the cover provided by a complacent media, have made serious action this decade unlikely.

The fact is the new study in Science is not terribly germane to what is happening now — as made clear by the study itself and expert quotes Revkin himself prints.

The study looks at one part of the Arctic during the Holocene Climate Optimum (aka the Holocene Thermal Maximum) and finds:

For several thousand years, there was much less sea ice in the Arctic Ocean — probably less than half of current amounts….

The results are based on material gathered along the coast of northern Greenland, which scientists expect will be the final place summer ice will survive, if global temperatures continue to rise.

The problem with the authors’ effort to generalize the results to modern times is that the HCO or HTM — 8500 to 6000 years ago — was utterly different than today. They write:

The period ~8.5 to 6 ky B.P. marks the Holocene Thermal Maximum (HTM) in this area. Long continuous beach ridges northward along the coast up to 83°N show that this was the southern limit of permanent sea ice, ~1000 km to the north of its present position. To the north of 83°N, beach ridges are restricted to bays and major river mouths, showing that this coast had permanent sea ice but was within the zone of coastal melt. Coastal melt is determined by local summer temperatures (15), and this indicates that summer temperatures during the HTM in north Greenland were 2° to 4°C warmer than now, as elsewhere in this part of the Arctic (17)….

In this exercise, our records would correspond in the model to an Arctic Ocean sea-ice cover in summer at 8 ky B.P. that was less than half of the record low 2007 level.

But the HTM warming wasn’t driven by rapidly-increasingly GHG levels, which have a significant thermal lag — that is, there is a lot more warming in the pipeline today. Also, today soot, or black carbon, is a major driver of Arctic melt, which means we’re getting melting beyond the warming temperatures from GHGs.

Finally, the HTM warming in the Arctic was driven by conditions that are utterly different than what we have today. The paragraph above ends citing reference 17, “Holocene thermal maximum in the western Arctic (0–180 ° W),” which is online here. It explains:

At the 16 terrestrial sites where quantitative estimates have been obtained, local HTM temperatures (primarily summer estimates) were on average 1.6 +/-.8 °C higher than present (approximate average of the 20th century), but the warming was time-transgressive across the western Arctic. As the precession-driven summer insolation anomaly peaked 12–10 ka (thousands of calendar years ago), warming was concentrated in northwest North America, while cool conditions lingered in the northeast.

Note that these are just summer temps and only regionally localized and relative to the average temperature of the last century (not, say, “now,” as the new article asserts).

Now we have warming that is year-round and global and accelerating rapidly. Revkin himself has two key quotes from experts trying to explain this:

James Overland, Pacific Marine Environmental Laboratory: “What the authors say is consistent with previous ideas. At the Holocene maximum the orbit was more elliptic and the axis was more tilted. We had very short hot summers and long cold winters. It is not clear which season would win out. A lot of proxies are for summer only so they slant the data too much for warming. It is hard to get models to be completely sea-ice free during this period, so this paper’s results are consistent. Other papers on erosion of Greenland beaches suggest the same thing. Bottom line is that current and historical sea ice cover is sensitive to changes in the radiation balance.”

Leonid Polyak of the Byrd Polar Research Center at Ohio State University notes that the general climatic and ice situation in the Arctic now appears very different than what prevailed in earlier Holocene warm periods: “Overall, the early-Holocene situation in the Arctic seems to be very different from the modern one. Now we are having the strongest ice retreat in the Pacific sector and ice pile-up near Greenland — practically the opposite to what Funder’s paper suggests for the early Holocene.”

In short, you can’t draw any lessons from this paper for today. And that’s without even factoring in the black carbon and thermal lag.

I repeat — we have passed a de facto tipping point. Yeah, you can devise a theoretical scenario of emissions reductions that might — might — stabilize the Arctic, but such a scenario is all but impossible in the face of implacable opposition by the deniers and their political allies, and it is precisely the kind of emissions reduction scenario Revkin himself constantly dismisses.The Arctic is all but certain to be virtually ice free within two decades (barring extreme volcanic activity). I’m happy to make bets with any bloggers, like Andy Revkin, that the Arctic will have under half the ice it has today by 2020, thus equaling or surpassing the lowest level identified in this Science paper. The death spiral continues.

Related Post:

  • Serreze (9/10): Arctic is “continuing down in a death spiral. Every bit of evidence we have says the ice is thinning.”

Below are old comments from the earlier Facebook commenting system:

Revkin is right that the timescales are not relevant to today’s policy discussions. That’s because our once great country is controlled by greed crazed oligarchs, many of whom have grown to love the dividends and appreciation from oil and coal company stocks. “Relevant time scales” is defined as “next year’s additions to my portfolio”. We are faced with a moral failure as much as a political and scientific one.

And thanks for getting the details right, Joe, including the new and quite abrupt tipping point. For scientists to counter it by plugging in a short term 60% emissions reduction is a little ridiculous.

17 · Like · Reply · Subscribe · August 9 at 4:15pm

Peter S. Mizla · Top Commenter · Vernon, Connecticut

One can ask who is the New York Times and Revkins ‘Daddy’

3 · Like · Reply · August 9 at 5:40pm

Joan Savage · Top Commenter · SUNY-ESF

Was that rhetorical?The NYTs recent executive editor was a son of the CEO of Chevron. One could ask if that relationship influenced editorial policy, but there are direct financial supporters of the Times who could be more influential.

1 · Like · Reply · August 10 at 1:53pm

Rakesh Malik · Top Commenter · Photographer/Owner at White Crane Photography

You’re right; today’s policy timescales could be measured in minutes.

Like · Reply · August 10 at 4:38pm

Peter S. Mizla · Top Commenter · Vernon, Connecticut

The Media will continue to ‘blow’ a story like this until they understand the science. And even then, the will be on a short leash (as they are now) by their corporate Masters.

7 · Like · Reply · Subscribe · August 9 at 7:13pm

Scott Mandia · Friends with Joseph Romm

The Inuit have a word for the weather now: uggianaqtuq. This means “not its usual self.”

6 · Like · Reply · Subscribe · August 9 at 4:44pm

Paul Magnus · Top Commenter

Apparently daylight is starting earlier and extending later up in the arctic. They are not sure why… cloud cover and lower ice horizons have been mentioned.

Seems to me that theres a feedback there somewhere. If the ice horizon drops and lets more sun energy in for longer periods then there is more melt!

1 · Like · Reply · August 10 at 1:58am

Andrew Sipocz · Purdue University

This paper reports that during the Holocene optimal there was half the summer (permanent) ice area as during 2007. As beach ridges don’t take that long to form, a few years fall storms would do it, then this means that at least half of the permanent ice area as compared to 2007, survived the Holocene optimum. Likely there were years when there was more ice, but as beach ridges are indicative of minimum ice extent, we know there was never less than that or never less for a period of time significant to polar bears, etc. (i.e. more than a few seasons total — and seasons that were not necessarily sequentially).

But, there’s no way in hell that ice melt will stop at half of 2007’s area. I’d flip over and kiss my butt in joy if I knew we were going to end up with that much ice when global warming is finally halted.

This study’s real…See More

5 · Like · Reply · Subscribe · August 9 at 7:19pm

John Poteet · Top Commenter · Chico, California

Say goodbye to whatever you think “normal weather” is locally in the northern hemisphere. You might get hotter, cooler, wetter or dryer but “normal” years are gone for the rest of your life.

5 · Like · Reply · Subscribe · August 9 at 4:30pm

Tom Gray · Top Commenter · Haverford College

There’s another story of concern from the past few days that bears on this issue — arguably a distortion, but even so, there are some unfortunate quotes/paraphrases. See , in which Mark Serreze of NSIDC opines that longer growing seasons will be a benefit of the dwindling ice (it’s at the end of the story… AND… in the headline). Regards, Tom Gray, Wind Energy Communications Consultant.

4 · Like · Reply · Subscribe · August 9 at 4:42pm

George Ennis · Top Commenter · University of Toronto

I read his comment. I would respectfully suggest that he knows not of what he speaks if he is suggesting warmer winters and springs will extend growing seasons and even allow farming to happen in places like Siberia or Canada’s north. Temperature is only one component. The other components are precipitation and soil. In the case of the former there may be an increase. In the case of the latter I doubt you could grown anything in the existing “soils” of the tundra.

Also even in those areas just south of the tundra there is in Canada a thing called the Canadian Shield and unless he knows of a way to grow crops on igneous rock that seems unlikely to happen.

7 · Like · Reply · August 9 at 5:35pm

Tom Gray · Top Commenter · Haverford College

I agree, not so much on the growing-season question as the larger issue many others have raised: we are causing what has seemed like a relatively stable system to become unglued, and we don’t really have a clear idea what the consequences are. In that context it is folly to talk about potential offsetting benefits.

5 · Like · Reply · August 9 at 9:34pm

Kevin McKinney · Atlanta, Georgia

Bingo. That’s why Canada isn’t an agricultural super-power in proportion to her surface area — muskeg and rock make for tough rooting. And the tundra won’t be any better, no matter how long the growing season.

1 · Like · Reply · August 9 at 11:46pm

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Barry Saxifrage · Top Commenter

Great post once again. Thanks Joe. I see a similar psychological dynamic in play in several recent posts (Dobbs, Spencer, Revkin, etc…) in which people who have long said there is nothing to worry about are now desperately grasping at straws to prove their call to inaction hasn’t been a catastrophic mistake.

I think it is becoming clear to everyday Americans that the weather is broken and getting dangerously extreme. People notice freaky weather and they talk about it a lot. A lot of the pundits who have scoffed at climate mitigation must have a very nasty sinking feeling in their gut right now. They desperately need to prove they haven’t sold out their nation’s future with their attacks on climate action. These folks will be increasingly desperate and pathetic in their “reasoning” as the weather continues to get more extreme and unpredictable.

How long until The Onion can just reprint the writings of these folks without any modification? About when the ice disappears from the Arctic is my guess.

3 · Like · Reply · Subscribe · August 10 at 12:17am

James Greyson

Great article. There is another dangerous feedback at work, enough so far to prevent effective policy responses. It’s rather simple: as people notice more happening among the symptoms (climate, weather, ice) we get more discussion around the symptoms. Even policy responses get defined at the end of the pipe, such as the UN’s focus on emissions cuts. Better as you do above to focus on GHG concentrations. Even better would be to focus on the strength of the mechanism for change. Emissions controls are the weakest imaginable mechanism. Concentration targets are a little stronger since they challenge incremental thinking. I suggest we focus on the global economy as a mechanism for change. This needs a point of inflection too where future growth can come from activity that reverses the problems it has previously caused.

Have set out how to do this in a proposal to the MIT Climate CoLab. Glad of support or criticism. Others with ideas on how to tackle climate are very welcome to add their proposals to the site.

2 · Like · Reply · Subscribe · August 10 at 3:44am

Peter S. Mizla · Top Commenter · Vernon, Connecticut

Ice decline in the arctic is declining again at a good pace. Weather looks warm, with sun for the next 2 weeks over most of the arctic. The NSIDC was down for 3 days- but is back up.

The Nature article was the talk of the Deniers- but as JR has said, there will be no cooling to bring ice back from the downward trend. The article also said the warmest part of the Holocene was 3,000 years ago- its actually 8K. C02 8K ago was 280ppm- at 393ppm today, we are to expect ice to reform?

2011 still has about a 50/50 chance of ice as low as 2007-…See More

2 · Like · Reply · Subscribe · August 9 at 5:17pm

Tony Raizis

Peter, this topic is relevant to our earlier discussion regarding methane reservoirs in the Siberian tundra/ESAS. You mentioned Hansen is unclear regarding the CO2/ppm that would be enought to set them off. It is quite possible, however, that CO2 is no longer critical and that the loss of the Arctic ice/albedo may become a more dominant factor. What are your thoughts on that?

Like · Reply · August 10 at 4:04am

Peter S. Mizla · Top Commenter · Vernon, Connecticut

Getting back to you Tony.

I am not a scientist- Well a social scientist — lol- but really- I had a Geography major- took the courses in Physical Geography and climatology-blah blah

I do understand what you mean- and C02 may not be the catalyst to set off methane. The mere melting of ice, and the albedo flip may be enough to set Ch4 soaring.

Point is, do want want to wait and see, as more ice melts? Huge gamble here.

Like · Reply · August 10 at 4:37pm

agres (signed in using Yahoo)

The loss of sea ice is interesting, but the melt of permafrost with subsequent, rapid biological evolution of CH4 is a really big story.

Once permafrost starts melting, there are feedbacks from changes in albedo, methane emissions, the thermal properties of surface water, and increases in atmospheric water vapor. Together, the feedbacks drive accelerated melt of permafrost. Ultimately, atmospheric circulation responds to the conversion of permafrost to wetlands. One effect of the changes in atmospheric circulation will be faster transfer of heat to the Greenland Ice Sheet.

However, the line between those wetlands being a large source of CH4 or a large carbon sink is a very fine one. These wetlands could cause catastrophic warming via CH4 releases or be the carbon sink that we need to control AGW. It may be possible to tip the balance one way or the other. We need to see if we can move the balance toward the wetlands being a carbon sink. It may be as simple as adding a few trace nutrients and seeding them with the right algae.

1 · Like · Reply · Subscribe · August 9 at 8:04pm

  • Prokaryotes — · Top Commenter (signed in using Hotmail)

Soil carbon and climate change: from the Jenkinson effect to the compost-bomb instability · Like · Reply · August 9 at 11:39pm

George Ennis · Top Commenter · University of Toronto

Thanks Joe. You cleared up a point I did not believe was clear in the news release for the new study when you stated: “How precisely is the climate going to return to cooler temperatures?”.

Since I do not have a subscription to Nature I did not feel I was in a position to meaningfully comment on the study, but I did think when I read it that it was odd.

As usual you have provided a succinct summary of the issue in the proper context of what is forcing the climate change today as opposed to what was forcing the climate 8,000 years ago.

As a Canadian I am well ware of the temperature anomalies that are being experienced in the Arctic. Anomaly in many cases does not do justice to the size of the temperature differential between actual and a given base period. For example I would encourage people to take a look at current sea surface temperature anomalies for Hudson Bay as an example.

1 · Like · Reply · Subscribe · August 9 at 4:59pm

shaheercassim (signed in using Yahoo)

There’s some discussion here on Arctic sea ice by Mike MacCracken, Andrew Lockley, and John Lathan.

On whether Arctic Sea Ice, once lost, could recoverPosted 8/8/11 10:09 AM, 4 OCEAN MELTS NOW 20% EACH 10 DAYS, RUSSIA’S NORTH-EAST PASSAGE OPENS FOR SHIPPING‏Posted 7/27/11 8:00 · Like · Reply · Subscribe · August 9 at 6:57pm

  • shaheercassim (signed in using Yahoo)

Links don’t appear to work. Perhaps you have to be signed into the group.

Like · Reply · August 9 at 7:07pm

Prokaryotes — · Top Commenter (signed in using Hotmail)

You need to post short urls (with url shortner like ) otherwise facebook causes the links to error

Like · Reply · August 9 at 11:40pm

Susan Shamel · Director, Medical & Religious Outreach at Global Warming Education Network

Andy Revkin doesn’t get IT. We attended a forum at which he spoke, hubby asked a question, and Andy queried, “First of all, what is “it?” Then later, in response to another question, he pointed at my husband and said, “That man’s grandkids will be fine.” Our grandkids are 3 and 7. Is he really so clueless as to believe that they’ll not suffer any consequences of AGW in their lifetime?

1 · Like · Reply · Subscribe · August 9 at 10:12pm

Prokaryotes — · Top Commenter (signed in using Hotmail)

What do you expect from someone who is the biggest concern troll in the US media and in exchange with Monckton’s email network.

Like · Reply · August 9 at 11:41pm

Prokaryotes — · Top Commenter (signed in using Hotmail) · Reply · August 9 at 11:42pm

Tenney Naumer · Top Commenter · Southern Illinois University Carbondale

It pains me to say this, but Andy Revkin really does not get it, not at all. He really doesn’t appear to be concerned about our future. He has a young son, so this is most unfortunate as he has an excellent bully pulpit, but uses it for giving voice to the most amazing junk science.

Like · Reply · August 10 at 9:38pm

Geo Hernandez · Top Commenter · Los Angeles, California

“…policies which are pushed by denier disinformation and sustained by media stenography.”

“Media stenography”, I like that one.

1 · Like · Reply · Subscribe · August 9 at 4:43pm

Terry Moran · Sitting, when not napping. at Retired, and Relieved

The point was tipped when Big Oil prevailed over science in the battle for the hearts and minds of policy makers in North America.

1 · Like · Reply · Subscribe · August 9 at 7:32pm

Prokaryotes — · Top Commenter (signed in using Hotmail)

On thin ice.The most recent global climate report fails to capture the reality of the changing Arctic seascape, according to MIT researchers. · Reply · Subscribe · August 11 at 3:29pm

John Borstelmann · Stanford University

Thanks, Joe, for cutting through the BS and presenting the actual science of what’s happening in the Arctic.

Like · Reply · Subscribe · August 10 at 10:53pm

Stuart Fischbach

Seems to be my night for Artic Ice Melt…

Like · Reply · Subscribe · August 11 at 11:25pm

Jakob Wranne

Question: Where is the best place to give, send or hand you or Climate Progress stories and links? Without drowning you?

1 · Like · Reply · Subscribe · August 11 at 2:51am

Danne Mikula · Enskede, Stockholms Lan, Sweden

Gilla är fel knapp för sånt

1 · Like · Reply · August 11 at 4:32am

Miguel Angel Ramirez Bocanegra · Coyoacán, Distrito Federal, Mexico

buen articulo

Like · Reply · Subscribe · August 11 at 8:40pm

Jai John Mitchell · Willits, California

the 2010 MIT model held global CH4 levels steady state until about 2080. Even so they predicted a 5–7 degree celsius increas by 2095.

Like · Reply · Subscribe · 20 hours ago

marcusmarcus (signed in using Yahoo)

While I agree with you that we are very likely committed to a future in which the Arctic will be nearly ice-free in September, I don’t agree that that constitutes a “tipping point”. A “tipping point” is a technical term which pretty much exactly corresponds to either “and this will keep happening even if we were to cool the climate after it starts”, or “this will happen if we cross a threshold temperature”. It doesn’t matter that it isn’t realistic politically, it is a physically based term. Arctic sea ice corresponds to neither “tipping point” definition: it is reversible (in theory), and it isn’t a threshold phenomena — rather, it gets worse for each increment of temperature.

Amazonian deforestation might be a tipping point, because if the jungle turns into savannah, the new savannah might persist even if we cool the temperature down. Commitment to Greenland’s deglaciation might be a tipping point (once the top of Greenland drops some critical number of meters, it will no longer be cold enough to keep accumulating snow even if we cool the climate back down). Collapse of the thermohaline circulation might be a tipping point under both definitions (eg, key threshold and irreversible).

I think it is still valuable to distinguish between “commitment” and “tipping point”.

Like · Reply · Subscribe · August 9 at 7:53pm

Joseph Romm · Top Commenter · Center for American Progress

I think “de facto tipping point” is perfectly fine. If things that are theoretically possible but practically impossible count, then “tipping point” has little meaning.

2 · Like · Reply · August 9 at 8:22pm

Prokaryotes — · Top Commenter (signed in using Hotmail)

The West Antarctic ice sheet is a potential tipping element of the climate system that might have partially tipped already. · Like · Reply · August 9 at 11:37pm

Jim Balter · Top Commenter · Santa Barbara, California

“It doesn’t matter that it isn’t realistic politically” — yes, it most certainly does … the only reason we care about tipping points is because of consequences and how policy affects them. If you just want to play pedantic semantics, then do it is some other area that doesn’t matter hugely.

Like · Reply · August 10 at 3:25pm

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Duncan Fitzpatrick · University of Sheffield

a couple of things to add if you will indulge me. From what I understand loss of sea ice on its own will not be a tipping point because sea ice can recover. This is not true of say releasing the carbon in the permafrost and this seems to be what the scientists in the paper are referring to. However I also understand that ice loss is exponential in its growth and that the loss of albedo of the arctic ice cap has the same effect as doubling co2 emissions and on that basis I reckon we ain’t in Kansas anymore. For me then its true to say that loss of sea ice on its own doesn’t mean the end of the Holocene but it does count as one hell of an accelerant. Please point out any errors in my logic with this as I am always trying to deepen my understanding.Also just read an article in yale e360 which states that the artic tundra has the same precipitation level as a desert. That seems to make the idea of farming this land even more outlandish.

Like · Reply · Subscribe · August 10 at 5:42pm

Richard Dudeney · Cranfield University

John Dabiri’s paper on vertical axis wind turbines looks very good, anyone know if this is as promising as it seems? paper here:

ResearchThe Dabiri Lab at Stanford University conducts research at the intersection of fluid mechanics, energy and environment…dabiri.caltech.eduLike · Reply · Subscribe · August 10 at 8:26am

  • catman306 (signed in using Yahoo)

Both of those links have vanished. Someone knows why.

Like · Reply · August 10 at 9:26pm

Tenney Naumer · Top Commenter · Southern Illinois University Carbondale

Here is another link: · Like · Reply · August 10 at 9:44pm

Richard Dudeney · Cranfield University

I’m confused the links work from FB but not when copy pasting them into Firefox address barthe paper can be also be found:

Like · Reply · August 11 at 2:33am

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Robert Fanney · Top Commenter · Flagler College

In the end, no profit comes from wrecking one’s environment. Ask the people of Easter Island.

Like · Reply · Subscribe · August 10 at 2:32pm

Capital Climate (signed in using Hotmail)

How can you criticize Revkin’s expertise on the Arctic? He’s actually been there at least once, so that makes him an instant authority.

Like · Reply · Subscribe · August 9 at 4:34pm

Peter S. Mizla · Top Commenter · Vernon, Connecticut

Revkin and the other naysayers have been proven wrong. Revkin and the NYT however I want to see eat grow. The NYT for years said it saw ‘no threat’ to human civilization from climate change.

Everyday weather is simply altered from the benign past we are used to. People are beginning to see this change. Climate sensitivity in regards to C02 has been proven right.

How long will it take for Revkin to admit he is wrong.

Like · Reply · August 10 at 5:54am

Bill Waterhouse

He could see the North Pole from his tent.

1 · Like · Reply · August 10 at 1:52pm

Paul Magnus · Top Commenter

Should we be swearing….

Like · Reply · Subscribe · August 10 at 1:55am

Fredrik Fyhr · Göteborg, Sweden

Godbye Artic sea ice.

Like · Reply · Subscribe · August 10 at 2:41pm

Bertrand Guillotin · 34 years old

Does anyone have an update of the first graph, or any recent data comparison with 10–30 year old global warming models ? Thank you.

Like · Reply · Subscribe · August 10 at 12:05pm

Rachel Muir · Reims, France

Never do I want to hear the words death spiral applied to anything having to do with geology, especially in the arctic.

Like · Reply · Subscribe · August 10 at 2:29pm

Andrew Wynne Davies

Deniers would make a meal of the fact that the bottom (red) line is, in fact, August.

Like · Reply · Subscribe · August 9 at 5:57pm

Joseph Romm · Top Commenter · Center for American Progress

Nah. Just a new graph.

Like · Reply · August 9 at 8:25pm