All Star Science Panel Drops Bombshell Climate Paper

March 22, 2016

The bombshell paper that James Hansen first released pre-publication last summer has now made it thru review to publication, in the journal Atmospheric Chemistry and Physics.(free online here)

The paper is significant for readers of this blog, because a year ago, I produced a video describing observations in the North Atlantic that are consistent with one of the main premises of the paper, a slowdown of Atlantic Overturning circulation – with scientists Stefan Rahmstorf, Michael Mann, and Jason Box. I’ve posted that video at the bottom.
Dr. Mann is quoted in the Washingon Post, (below) expressing some reservations about the new study, so room for a follow up there.

Above, in my December interview, Hansen gives a quick thumbnail. Below, his new video has a more detailed, illustrated description.

PBS Nova:

The world’s oceans could rise catastrophically as soon as 50 years from now, according to a new paper published this morning in Atmospheric Chemistry and Physics.

The researchers behind the paper—Dr. James Hansen and 18 coauthors—looked back to 120,000 years ago, the last time the Earth warmed by the about the same amount it has today. (Global temperatures are now 1˚ C, or 1.8˚ F, above preindustrial levels.) Back then, natural warming unleashed nearly all of the water locked in polar ice sheets, sending sea levels surging 20-30 feet higher.

Washington Post:

An influential group of scientists led by James Hansen, the former NASA scientist often credited with having drawn the first major attention to climate change in 1988 congressional testimony, has published a dire climate study that suggests the impact of global warming will be quicker and more catastrophic than generally envisioned.

The research invokes collapsing ice sheets, violent megastorms and even the hurling of boulders by giant waves in its quest to suggest that even 2 degrees Celsius of global warming above pre-industrial levels would be far too much. Hansen has called it the most important work he has ever done.

The sweeping paper, 52 pages in length and with 19 authors, draws on evidence from ancient climate change or “paleo-climatology,” as well as climate experiments using computer models and some modern observations. Calling it a “paper” really isn’t quite right — it’s actually a synthesis of a wide range of old, and new, evidence.

“I think almost everybody who’s really familiar with both paleo and modern is now very concerned that we are approaching, if we have not passed, the points at which we have locked in really big changes for young people and future generations,” Hansen said in an interview.

The research, appearing Tuesday in the open-access journal Atmospheric Chemistry and Physics, has had a long and controversial path to life, having first appeared as a “discussion paper” in the same journal, subject to live, online peer review — a novel but increasingly influential form of scientific publishing. Hansen first told the press about the research last summer, before this process was completed, leading to criticism from some journalists and also fellow scientists that he might be jumping the gun.

What ensued was a high-profile debate, both because of the dramatic claims and Hansen’s formidable reputation. And his numerous co-authors, including Greenland and Antarctic ice experts and a leader of the United Nations’ Intergovernmental Panel on Climate Change, were nothing to be sniffed at.

After record downloads for the study and an intense public review process, a revised version of the paper has now been accepted, according to both Hansen and Barbara Ferreira, media and communications manager for the European Geophysical Union, which publishes Atmospheric Chemistry and Physics. Indeed, the article is now freely readable on the Atmospheric Chemistry and Physics website.

The paper, according to Ferreira, was subject to “major revisions in terms of organisation, title and conclusions.” Those came in response to criticisms that can all be read publicly at the journal’s website. The paper also now has two additional authors.

Most notably, perhaps, the editorial process led to the removal of the use of the phrase “highly dangerous,” in the paper’s title, to describe warming the planet by 2 degrees Celsius above pre-industrial levels.

The original paper’s title was “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming is highly dangerous.” The final title is “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 °C global warming could be dangerous.”

But nonetheless, James Hansen’s climate catastrophe scenario now takes its place in the official scientific literature relatively intact. So let’s rehearse that scenario, again, for the record.

Hansen and his colleagues think that major melting of Greenland and Antarctica can not only happen quite fast — leading to as much as several meters of sea level rise in the space of a century, depending on how quickly melt rates double — but that this melting will have dramatic climate change consequences, beyond merely raising sea levels.

That’s because, they postulate, melting will cause a “stratification” of the polar oceans. What this means is that it will trap a pool of cold, fresh meltwater atop the ocean surface, with a warmer ocean layer beneath. We have actually seen a possible hint of this with the anomalously cold “blob” of ocean water off the southern coast of Greenland, which some have attributed to Greenland’s melting.

Indeed, shortly before the new paper’s publication, the National Oceanic and Atmospheric Administration released new recent data on the globe’s temperature that certainly bears a resemblance to what Hansen is talking about. For not only was the globe at a record warmth overall over the last three months, but it also showed anomalous cool patches in regions that Hansen suspects are being caused by ice melt – below Greenland, and also off the tip of the Antarctic peninsula.


Stratification, the key idea in the new paper, means that warm ocean water would potentially reach the base of ice sheets that sit below sea level, melting them from below (and causing more ice melt and thus, stratification). It also means, in Hansen’s paper, a slowdown or even eventual shutdown of the overturning circulation in the Atlantic ocean, due to too much freshening in the North Atlantic off and around Greenland, and also a weakening of another overturning circulation in the Southern Ocean.

This, in turn, causes cooling in the North Atlantic region, even as global warming creates a warmer equatorial region. This growing north-south temperature differential, in the study, drives more intense mid-latitude cyclones, or storms. The study suggests such storms may kick up gigantic oceanic waves, which may even be capable of feats such as hurling boulders in some locations, not unlike the huge rocks seen on the Bahamian island of Eleuthera, which I visited with Hansen and his co-author, geologist Paul Hearty, in November.

These rocks play a key role in the new paper, just as they did in the original study draft. Indeed, long before the current paper, Hearty had documented, in peer reviewed publications, that Eleuthera’s rocks appear to have come from the ocean and to have been lifted high up onto a coastal ridge. This appears to have happened during a past warm period, the Eemian, some 120,000 years ago, when the planet was only slightly warmer than today but seas were far higher — but the idea is that something like it could happen again.

The paper contains many ideas and departures, but the key one is its suggestion of the possibility of greater sea level rise in this century than forecast by the United Nations’ Intergovernmental Panel on Climate Change.

“The models that were run for the IPCC report did not include ice melt,” Hansen said in a press conference regarding the new paper Monday. “And we also conclude that most models, ours included, have excessive small scale mixing, and that tends to limit the effect of this freshwater lens on the ocean surface from melting of Greenland and Antarctica.”

Michael Mann, a Penn State university climate scientist familiar with the original study, commented, “Near as I can tell, the issues that caused me concern originally still remain in the revised manuscript. Namely, the projected amounts of meltwater seem unphysically large, and the ocean component of their model doesn’t resolve key wind-driven current systems (e.g. the Gulf Stream) which help transport heat poleward. That makes northern hemisphere temperatures in their study too sensitive to changes in the  Atlantic meridional overturning ocean circulation,” the scientific name for the ocean circulation in the Atlantic that, the study suggests, could shut down.

New York Times:

The paper identifies a specific mechanism that the scientists say they believe could help cause such an abrupt climate shift.

Their idea is that the initial melting of the great ice sheets will put a cap of relatively fresh water on the ocean surfaces near Antarctica and Greenland. That, they think, will slow or even shut down the system of ocean currents that redistributes heat around the planet and allows some of it to escape into space.

Warmth will then accumulate in the deeper parts of the ocean, the scientists think, speeding the melting of parts of the ice sheets that sit below sea level. In addition, a wider temperature difference between the tropics and the poles will encourage powerful storms. The paper cites evidence, much of it contested, that immense storms happened during the warm period 120,000 years ago.

The idea of a shutdown in the ocean circulation because of global warming was considered more than a decade ago, and it was rejected by most scientists as unlikely. That did not stop a distorted version of the idea from becoming the premise of the disaster movie “The Day After Tomorrow,” released in 2004.

The new paper may reopen that debate, forcing scientists to re-examine the idea with the more sophisticated computer models of the climate that are available today.

Even scientists wary of the conclusions of the new paper point out that Dr. Hansen has a long history of being ahead of the curve in climate science. As Dr. Mann put it, “I think we ignore James Hansen at our peril.”

Note: the NYTimes piece talks about shutdown of AMOC as being unlikely but does not mention Stefan Rahmstorf’s paper of a year ago, with Mann and Box.

38 Responses to “All Star Science Panel Drops Bombshell Climate Paper”

  1. Gary Evans Says:

    News of this appeared in the Guardian early this morning:

    The picture Hansen paints is truly apocalyptic in comparison with the conservative IPCC. It spells disaster for people trying to plan flood defences. London is not prepared for this new reality.

    I just hope I’m not around when the Thames Barrier finally fails.

    • rlmrdl Says:

      If he is right about the southern ocean gradients, then the southern hemisphere will see those mega storms right through South America, Southern Africa, NZ and Australia.

      As a kiwi who lives across the 45th parrallel, that puts me in the firing line for storms with wind speeds in the multuple hundreds of KPH. With not much land to interrupt them, the question of whether any of those storms might become permanent systems like Jupiter’s red spot also arises.

      It is now not beyond the bounds of possibility that my homeland will be scraped down to the bones.

  2. Prior to MLO the atmospheric CO2 concentrations, both paleo ice cores and inconsistent contemporary grab samples, were massive wags. Instrumental data at some of NOAA’s tall towers passed through 400 ppm years before MLO reached that level. IPCC AR5 TS.6.2 cites uncertainty in CO2 concentrations over land. Preliminary data from OCO-2 suggests that CO2 is not as well mixed as assumed. Per IPCC AR5 WG1 chapter 6 mankind’s share of the atmosphere’s natural CO2 is basically unknown, could be anywhere from 4% to 96%. (IPCC AR5 Ch 6, Figure 6.1, Table 6.1)
    The major global C reservoirs (not CO2 per se, C is a precursor proxy for CO2), i.e. oceans, atmosphere, vegetation & soil, contain over 45,000 Pg (Gt) of C. Over 90% of this C reserve is in the oceans. Between these reservoirs ebb and flow hundreds of Pg C per year, the great fluxes. For instance, vegetation absorbs C for photosynthesis producing plants and O2. When the plants die and decay they release C. A divinely maintained balance of perfection for thousands of years, now unbalanced by mankind’s evil use of fossil fuels.
    So just how much net C does mankind’s evil fossil fuel consumption add to this perfectly balanced 45,000 Gt cauldron of churning, boiling, fluxing C? 4 Gt C. That’s correct, 4. Not 4,000, not 400, 4! How are we supposed to take this seriously? (Anyway 4 is totally assumed/fabricated to make the numbers work.)
    IPCC AR5 attributes 2 W/m^2 of unbalancing RF due to the increased CO2 concentration between 1750 and 2011 (Fig TS.7, SPM Fig 5.). In the overall global heat balance 2 W (watt is power, not energy) is lost in the magnitudes and uncertainties (Graphic Trenberth et. al. 2011) of: ToA, 340 +/- 10, fluctuating albedos of clouds, snow and ice, reflection, absorption and release of heat from evaporation and condensation of the ocean and water vapor cycle. (IPCC AR5 Ch 8, FAQ 8.1)
    IPCC AR5 acknowledges the LTT pause/hiatus/lull/stasis in Text Box 9.2 and laments the failure of the GCMs to model it. If IPCC can’t explain the pause, they can’t explain the cause. IPCC GCMs don’t work because IPCC exaggerates climate sensitivity (TS 6.2), of CO2/GHGs RF in the power flux balance and dismisses the role of water vapor because man does not cause nor control it.
    The sea ice and sheet ice is expanding not shrinking, polar bear population is the highest in decades, the weather (30 years = climate) is less extreme not more, the sea level rise is not accelerating, the GCM’s are repeat failures, the CAGW hypothesis is coming unraveled, COP21 turned into yet another empty and embarrassing fiasco, IPCC AR6 will mimic SNL’s Roseanne Roseannadanna, “Well, neeeveeer mind!!”
    One can only hope that 2016 will be the year honest science prevails. In the meantime the hyperbolic CAGW hotterist’s hysteria will continue to fleece the fearful, neurotic and gullible, (i.e. the world’s second oldest profession).

    • grindupbaker Says:

      Poor shill job from you, too low key. If you are going to do a job then do it right. Your “The major global C reservoirs (not CO2 per se, C is a precursor proxy for CO2), i.e. oceans, atmosphere, vegetation & soil, contain over 45,000 Pg (Gt)” is wildly incorrect. The major irrelevant global C reservoir of Earth is the mantle with 400,000,000 Gtc, some 9,000 times as much as your puny and totally irrelevant “45,000 Pg (Gt)”. My totally-irrelevant data can wipe the floor with your totally-irrelevant data any day, and it’s far far easier on our brains, yours and mine, than doing actually-useful scientific ponderings.

      Why even the puny continents of Earth’s puny crust has 80,000,000 Gtc of CaCO3 etc, some 1,800 times as much as your puny and totally irrelevant “45,000 Pg (Gt)”.

      I bet they find even more irrelevant larger reservoirs of C on other planets in other galaxies one day. In short, the 45,000 GtC in carbonates in the deep ocean interacts with the atmosphere only on geologic time scales, millions of years, tens of millions of years, hundreds of millions of years and is totally irrelevant over the next puny few thousand years.

    • Jim Housman Says:

      You lost me at “devinely maintained”.

    • Sir Charles Says:

      We can see again: Science is evolving, climate change denial is not.

    • Hit and run. Google Search “both paleo ice cores and inconsistent contemporary grab samples”. At the time I ran the query Google was saying there were about 170 results.

      Don’t expect this guy to come back and respond to you. He has been posting this comment word for word every place he can since at least October of last year.

    • Lionel Smith Says:

      I think somebody has just vomited, regurgitating something posted on a facebook page last year.

      Bolder, Colorado eh! Maybe you should try asking around if any points you tried to make in that idea salad have coherence.

  3. grindupbaker Says:

    This seemingly contradicts Eeelco Rohling talk that SLR rate did not exceeed 1.0m to 1.5m / century with present Earth ice quantity per paleoclimate analyses.

  4. GarryRogers Says:

    Reblogged this on GarryRogers Nature Conservation and commented:
    Homogenic climate change is already too rapid for Earth’s ecosystems. And now our experts are warning us that truly abrupt changes may be coming. How can we not act when unconscionable devastation of habitats and wildlife is already occurring?

  5. […] Source: All Star Science Panel Drops Bombshell Climate Paper […]

  6. From the post:

    Note: the NYTimes piece talks about shutdown of AMOC as being unlikely but does not mention Stefan Rahmstorf’s paper of a year ago, with Mann and Box.

    That would be the paper that ends with the sentence:

    This might lead to further weakening of the AMOC within a decade or two, and possibly even more permanent shutdown of Labrador Sea convection as a result of global warming, as has been predicted by some climate models.

    Rahmstorf, S., Box, J., Feulner, G., Mann, M.E., Robinson, A., Rutherford, S., Schaffernicht, E. Evidence for an exceptional 20th-Century slowdown in Atlantic Ocean overturning, Nature Climate Change, 5, 475–480, 2015.

    … which is available at:

    Michael E. Mann: Articles

  7. Apparently even without the findings of Rahmstorf et al. (2015) experts in the field are concerned that the risk of a complete shutdown of the Atlantic Meridional is quite possible:

    If the circulation weakens too much it can even completely break down – the AMOC has a well-known “tipping point” (Lenton et al., 2008). The latest IPCC report (just like the previous one) estimates a probability of up to 10% that this could happen as early as this century. However, this assessment is based on models that may underestimate the risk, as mentioned above. Expert surveys indicate that many researchers assess the risk higher than the (generally conservative) IPCC, as is the case for sea level. In a detailed survey (Kriegler et al 2009), the 16 experts interviewed saw already at moderate global warming (2-4 °C) a probability of a ‘tipping’ (major reorganisation) of the flow between 5 and 40 percent. With strong global warming (4-8 °C) this probability was even estimated as between 20 and 65 percent.

    What’s going on in the North Atlantic?
    Stefan Rahmstorf, 23 Mar 2015

    • CORRECTION: The first sentence should have read, “Apparently even without the findings of Rahmstorf et al. (2015) experts in the field are concerned that a complete shutdown of the Atlantic Meridional Overturning Circulation is quite possible:”

      I was a bit distracted (my wife was talking about Bucky Barns and Steve Rogers) and should have checked the comment before hitting “post”.

  8. Interestingly, a weakening of the Atlantic Meridional Overturning Circulation would temporarily cool Europe, but unlike what is envisioned in “The Day After Tomorrow” it might actually warm the US East Coast.

    Please see:

    There is a strong case that the warm SST off the US coast and the cold blob in the subpolar gyre are linked, both being caused by an AMOC slowdown. This AMOC slowdown thus may have consequences for extreme weather in the US that I did not foresee in the past and only started to think about in the last year.

    Blizzard Jonas and the slowdown of the Gulf Stream System
    Stefan Rahmstorf, 24 Jan 2016

    One other point… Much of the heat that is radiated to space is radiated from the polar regions where due to the dryness o the atmosphere it is more transparent to longwave radiation. If one reduces poleward heat transport it would seem this will actually increase the imbalance between incoming shortwave radiation and outgoing longwave. As such this would be a positive feedback, resulting in greater global warming.

  9. redskylite Says:

    Thanks for keeping us all abreast of the latest news and for all your great informative videos. Phil Plait gives Peter a great mention in his Slate piece “If Global Warming Is Real … Why Is Iceland So Cold?” dated March 22 2016.

    It turns out this blob is not just some random fluctuation. In fact, counterintuitively, global warming predicts this cold spot! Peter Sinclair, who makes very well thought-out and simple climate change videos, made an excellent one last year explaining this pretty clearly:

    If Global Warming Is Real … Why Is Iceland So Cold?In a nutshell, there’s a flow of water in the Atlantic Ocean that brings cold water down from the polar region, and warm water to the poles. It’s called the Atlantic Meridional Overturning Circulation, or AMOC, but you can think of it as a conveyor belt of heat. It depends on a lot of factors, but it turns out one very strong influence is how salty the water is. Fresh water is less dense than salt water and floats on top of it.

    • redskylite Says:

      And Slates narrative on the Dr J.Hansen et al. paper, authored by Eric Holthaus

      James Hansen’s Bombshell Climate Warning Is Now Part of the Scientific Canon

      The result was so important that Hansen didn’t want to wait. So he called a press conference and distributed a draft of his findings before they could be peer-reviewed—a very nontraditional approach for a study with such far-reaching consequence. Now, after months of intense and uncharacteristically public scrutiny by the scientific community, the findings by Hansen and his 18 co-authors have passed formal peer review and were published Tuesday in the journal Atmospheric Chemistry and Physics.

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