The Long Thaw

The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth's Climate

The legacy of our release of fossil fuel CO2 to the atmosphere will be long-lasting. It will affect the Earth’s climate for millenia. We are becoming players in geologic time. That is the conclusion that climatologist David Archer shares with a general audience in his newly published book The Long Thaw: How Humans Are Changing the Next 100,000 Years of Earth’s Climate.

The author is a professor in the Department of The Geophysical Sciences at the University of Chicago and a contributing editor at Real Climate. His book is relaxed in style, almost conversational sometimes, repetitive on occasion, but nevertheless closely focused and packed with instructive detail. It was a pleasure for a non-scientist like me to read. He seems to understand how to illuminate processes for the general reader. For example, his chapter on the distribution of carbon in the atmosphere, the land and the ocean, and his explanation of the interactions between them in the carbon cycle, provided angles and information that pulled together satisfyingly the bits and pieces of my hesitant understanding.   Similarly what he writes about the acidifying of the ocean by CO2 and the part calcium carbonate plays in slowly neutralising its effect is a model of lucidity.

The book’s structure is simple.  There are three sections.  The first describes the situation we are in right now – meaning the 20th and 21st centuries.  The second section is about the past, investigated as a forecast for the future.  The final section looks into the deep future.

Archer produces no surprises about our current situation.  The basic physics of the greenhouse effect – that gases in the atmosphere that absorb infrared radiation could eventually warm up the surface of the earth – was described in 1827 by the French mathematician Fourier. Then in 1896 Swedish chemist Arrhenius estimated the amount of warming that the Earth would undergo on average from a doubling of the atmospheric CO2 concentration – what we now call the climate sensitivity. Such work sets the scene for the climate science which has exploded in the past few decades as global warming grew from a prediction into an observation.    He describes many aspects of our current understanding of global warming, with several particularly helpful sequences, such as that on the relative strengths of four external agents of climate change called climate forcings – greenhouse gases, sulfur from burning coal, volcanic eruptions, changes in intensity of the sun. The warming that is occurring cannot be explained by natural forcings.  Looking ahead in the present century he is very aware that sea level rise by 2100 may well be higher than predicted by the IPCC, as it begins to appear that the ice models used to forecast may be too sluggish to predict the behaviour of real ice.

In the second section he moves steadily back in time, starting with the last 100,000 years where the abruptness of some of the changes detected leads him to reflect that the IPCC forecast of a smooth rise in temperature from 0.5 degrees excess warmth today  to about 3.0 degrees excess warmth in 2100 represents a best-case scenario in that it contains no unfortunate surprises. He then treats the longer-term glacial climate cycles through the last 650,000 years, paying attention to orbital forcing and to the ups and downs of atmospheric CO2 through the cycles.  He envisages the ice sheets and CO2entwined in a feedback loop of cause and effect, like two figure skaters twirling and throwing each other around on the rink.” His final step back is to the hothouse world of 50 million years ago and beyond that to transitions between hothouse and ice age climates over 500 million years. He selects the Paleocene Eocene Thermal Maximum event (recently discussed on Hot Topic) as an analogue for the global warming future.

The third section looks at that future.  In discussing the land’s and ocean’s ability to take up carbon being released from fossil fuels he considers it likely that there are limits to that process which will mean that a significant fraction of fossil fuel CO2 will remain in the atmosphere for millenia into the future.  There are calming effects from the carbon cycle, but there can also be opposite effects as seems likely to have been the case at times in the past.  Hopefully large scale methane hydrate release won’t be a large part of such feedbacks, but if the ocean gets warm enough it is possible and could double the long-term climate impact of global warming.

For now the carbon cycle is responding to the CO2 increase by inhaling the gas into the ocean and high-latitude land surface, damping down the warming effect. But on the timescale of centuries and longer the lesson from the past is that this situation could reverse itself, and the warming planet could cause the natural carbon cycle to exhale CO2, amplifying the human-induced climate changes.

The clearest long-term impact of fossil-fuel CO2 release is on sea level rise.  The book has a restrained chapter on this, but there is no escaping what will happen if the ice sheets melt. “We have the capacity to ultimately sacrifice the land under our feet.

Have we averted an ice age?  Archer discusses this possibility, but finds the evidence uncertain.  He would in any case not put such a possibility forward as an argument in favour of CO2 emissions. All it means is that natural cooling driven by orbital variation is unlikely to save us from global warming – at this stage the much greater danger. Incidentally he mentions Ruddiman’s book Plows, Plagues, and Petroleum briefly and appreciatively in this section, but gives reasons for doubting its conclusions. (The book was reviewed on Hot Topic recently.)

In his epilogue on economics and ethics, where he ponders whether we are likely to turn away from the path we are currently on, he offers a comparison with slavery, another ethical issue: “Ultimately it didn’t matter whether it was economically beneficial or costly to give up. It was simply wrong.”

James Hansen describes the book as the best about carbon dioxide and climate change that he has read.  “David Archer knows what he is talking about.” To which I would add that he also knows how to explain it clearly to anyone prepared to give him reasonable attention.

12 thoughts on “The Long Thaw”

  1. Good article — and up to date, but there are several comments that I would like to make about “Global Warming.

    The first is that this is NOT a new effect. It has occurred five time during the past 400,000 years! First we need to discuss the sources of Methane that is actually the source of global warming. Anything that has grown, from yard clippings to a decaying body, produces methane as it decomposes. Methane from permafrost is a decay product. Methane from the deep ocean (methane hydrate) is totally different. Methane from oil wells is yet a very different composition. These must be recognized as such and understood as to their manner of existence, production, and/or release.

    Deep sea Methane appears to be the waste product of a bacteriological process, and therefore, is therefore a renewable resource! It is a relative clean product of our environment. It has recently been produced in commercial quantities by Japanese scientists in Canada.

    Oil well Methane is a very dirty gas — it is methane with huge amounts of sulfur and other noxious gases mixed with it.The Methane often mentioned in the media as “Bubbling up from Undersea Permafrost” is a decay product.

    Next — Drastic Global Climate Change has taken place at least five different times during the last 400,000 years. Our present cycle is the only one during which man has been a factor. (Ref. 1)Methane gas which bubbles up continuously from the deep ocean sources (which in turn disassociates into CO2) is the true source of the “Greenhouse Gas” that has operated in the previous five interglacial cycles — all of which have been extinction cycles!

    These five previous cycles are NOT man made effects, and it IS TOO LATE to change our present cycle, We can only learn to adapt! We cannot STOP the process although we might slow it down for a few years, which in geological time is nothing.

    JCSpilman a.k..a. Shamus12017


    There are several prime references associated with the material that I have covered, if ever so briefly.

    (1) Earth’s Changing Climate. Lecture Series by Dr. Richard Wolfson, the Benjamin F. Wissler Professor of Physics at Middlebury College. This is a six hour lecture series (12 segments of 30 minutes each) on two DVDs produced by The Teaching Company of Chantilly VA 20151-1232.

    This series covers in-depth detail of the science and methodology of climate change. It is not an advocacy program. Interestingly, Dr. Wolfson does not even mention Methane-Clatherate in this lecture series — knowledge on that subject is almost too new to have been included.

    (2) FIRE IN THE ICE. Quarterly Journal , U.S.Department of Energy, Office of Fossil Energy, National Energy Technology Laboratory. Also known as Methane Hydrate Newsletter. Recommended reading is all issues to current issue from about 2000 forward. This is the best of several technical journals devoted to the science of Methane Clatherates.

    (3) HIGH TIDE by Mark Lynas. Picador, 175 Fifth Avenue, New York, NY. 10010. ISBN 0-312-30365-3. This well written book clarifies the problems of Global Warming “… The American People have been subjected to one of the most pervasive misinformation campaigns ever undertaken …”

    (4) WITH SPEED AND VIOLENCE [Why scientists fear tipping points in Climate Change] by Fred Pearce. Beacon Press; 25 Beacon Street;Boston, MA 02108. © 2007. “We are on the precipice of climate system tipping points beyond which there is no redemption”


    JCSpilman, Huntsville, AL a.k.a.Shamus12017===============================Extensive REFERENCES furnished on request.JCSpilman

  2. JC Spilman

    Thanks for your comments. The reference to the Fire in the Ice journal was useful – I was unaware of its existence. I watched an interesting lecture not so long ago given by Miriam Kastner of the Scripps Institution of Oceanography entitled Methane Hydrates: Natural Hazard of Natural Resource. It’s available for free download from the iTunes store – a bit complicated to get to it, but if anyone’s interested you choose iTunes U under genres, then Beyond Campus in the panel Find Education Providers, then UCTV, then Science in the Subjects panel, then the video tab if you want to see it, or audio if you prefer. The last time I looked it was no.5. Incidentally no.4, which precedes it, is a lecture by James Hansen.

    I can only hope you’re wrong when say it’s too late to stop , if you are referring to the anthropogenic warming. Certainly there seem to be latent effects which we can no longer prevent, but a serious drop in the level of emissions, combined with a variety of measures to capture and sequester CO2 from the atmosphere surely still offer some hope. Some recent posts in Hot Topic to illustrate:
    None of the books I have read other than James Lovelock’s are yet ready to delcare the battle lost, and even he occasionally allows a little snippet of hope.

    Mr. Walker —
    Let me try different spin on my “Too late to stop comment” — it appears to me that the tipping point on global warming and sea level rise took place about the time man was migrating across the Arctic Ice Shelf and into North America. The sea levels began to rise along with temperature, salinity, current flow and other factors and the ice started melting across the world. The ice sheaths across America began their pull back and glaciers around the world did likewise. Arctic and Anctartic ice shelves starting thinning and man prospered.

    The sea levels rose (they are still rising) and the biological processes among the methane producing bacteria reduced their production of methane, the cycle of “global warming” started its very slow reversal and is once again headed down into the next interglacial ice age.

    There is nothing we can do to stop the present cycle, nor should we want to do so, nor should we waste huge sums of money on ineffective attempts to “reduce CO2 in the atmosphere”. Money is a tool to be used for good and must be applied to those areas that will permit mankind to adapt and survive the remainder of the heating cycle until we head back to the era of snowball earth.

    JCSpilman, P.E.; Huntsville, AL

  4. JC Spilman:
    I did wonder whether you were perhaps referring to natural cycles when you spoke of it being too late to stop, but there was enough in your original comment to suggest that you took the anthropogenic contribution to warming as significant. None of the scientists who warn of the dangers of what we are doing by continuing to release CO2 from fossil fuel into the atmosphere seems to me unaware of the long cycles you refer to. But they see the global warming process we have set in motion as large enough to override any natural cycle we would otherwise face and its extremes as perhaps avoidable if we take appropriate mitigation measures now. Adapting will be part of what we have to do – always have to do – but it seems to me the case is well and truly made for trying to reduce CO2. David Archer refers at the end of his book to the release of fossil fuel CO2 as having “enormous world-altering potential” . In effect he considers we have taken over the reins of Earth’s climate from the natural systems, and he ends with the hope that we’ll use our new powers wisely. To me that means mitigation if we can summon the will to undertake it.

  5. Bryan —

    I would like to add one additional reference to my earlier listing:

    (5) Natural Gas Hydrate Studies in Canada; Hyndman & Dallimore from The Recorder, 26,11-20, 2001, Canadian Society of Exploration Geophysicists.

    While not a recent document (it is seven years old) it does cover the basics of methane-hydrates with some outstanding charts and illustrations.

    In addition — so that you will know the sort of individual, with which you are discussing this subject, please GOOGLE my unique penname JCSpilman to see what my other interests are. Last time I tried that I got about 16,000 hits, which seemed a bit much.

    By way of introduction – I am a Graduate of Purdue University, 1949, in Electrical Engineering and am a retired Rocket Scientist (whatever that means) in 1985. Current age is 83 and shooting for 100!

    My favorite quotation is from Jacob Perkins, ca 1785 “Time proves all things”

    JCSpilman a.k.a.Shamus12017

    [Posted by GR for JCS – who sent this an email reply — you need to post comments on this page at HT, JCS]

  6. This thread was supposed to be about The Long Thaw.

    JCSpilman: have you read that yet?
    or Archer’s “Global Warming – Understanding the Forecast”?

    As it happens, Archer is a *world-class expert* not only on climate in general, but specifically in ocean processes and methane hydrates. Here’s his web page, and here are some publications, which are easy enough to check via Google Scholar.

    PLEASE: read some good introductory books by real climate scientists.
    Look at the reviews for The Long Thaw [thanks Byran for adding one]. and consider spending $50 for the 3 books I mention, to start building a *coherent* knowledge base about this topic.

    If you want more, you might try reading how to learn, and especially looking at Spencer Weart’s Discovery of Global Warming.

  7. Many thanks. Unfortunately there are too many irons in my fire to read everything suggested, and my interests are too diverse. About a year ago my wife and I were at a meeting with two folk with PhDs in Chemistry – a man and wife — and I asked them during our conversation whether they could brief me quickly on the chemistry of Methane-Clatherates. Neither one of them had any idea as to what I was talking about!

    “Time proves all things.” Bye.

  8. David Archer has a new interesting post on Real Climate in which he develops his “long tail” of CO2 release in relation to Susan Solomon’s recent paper in the Proceedings of the National Academy of Sciences entitled Irreversible Climate Change because of Carbon Dioxide Emissions. He points our that Irreversible doesn’t mean Unstopppable and emphasises that continuing with business-as-usual threatens far greater changes than we have so far initiated. The important thing is to stop while there is still some chance.

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