What triggered the Palaeocene-Eocene thermal maximum (PETM) about 55 million years ago, which saw the fastest period of warming documented in Earth's geological history? The PETM is associated with a rapid rise in greenhouse gases, particularly methane -- but the big question is where did the methane come from?
The most common answer has been the ocean (methane hydrates), but new research in Nature ($ub. req'd) casts doubt on the ocean theory -- instead finding chemical evidence that the methane came from terrestrial sources, bogs, which were themselves stimulated by rising temperatures -- an amplifying feedback. The lead author says:
A lot of temperate and polar wetlands are going to be wetter, and of course warmer as well [because of current climate change]. That implies a switch to more anaerobic conditions which are more likely to release methane. That's what's predicted, and that would be a positive feedback -- and we have evidence now that this is what happened.
Indeed, research from last year found "thawing Siberian bogs are releasing more of the greenhouse gas methane than previously believed." Why should we care about the source of the PETM?
Consider what scientists found when they analyzed data from a major expedition to retrieve deep marine sediments beneath the Arctic to understand the PETM, which they describe as a "widespread, extreme climatic warming that was associated with massive atmospheric greenhouse gas input." This 2006 study, published in Nature ($ub. req'd), found Arctic temperatures almost beyond imagination -- above 23°C (74°F) -- temperatures more than 18°F warmer than current climate models had predicted, when applied to this period. The three dozen authors conclude that existing climate models are missing crucial feedbacks that can significantly amplify polar warming.
That our climate models are underestimating global warming is a point I have made many times. If bogs were a major amplifying feedback for the PETM, we may be in for "widespread, extreme climatic warming" if we don't act quickly to slash greenhouse-gas emissions before the same feedbacks kick in again this century.
This post was created for ClimateProgress.org, a project of the Center for American Progress Action Fund.
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Comments
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Sam Wells Posted 8:58 am
21 Sep 2007
I know bogs on the East Coast, and fooled with some that was mud you could dry and cook like cheap sucky charcoal, like bricks. Heck man, there's even "quaking bogs." I think you're talking about some arctic permafrost, which might be totally different. Maybe I need some more education here.
Love to hear more on the subject. Seems different.
Onward through the fog
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Pangolin Posted 11:22 am
21 Sep 2007
Peat bogs harbour carbon time bomb- New Scientist.
Peat bogs are a vast natural reservoir of organic carbon. By one estimate, the bogs of Europe, Siberia and North America hold the equivalent of 70 years of global industrial emissions. But concern is growing that such bogs are releasing ever more of their carbon into rivers in the form of dissolved organic carbon (DOC).
Think of it as a massive compost pile that's just waiting to release all of it's stored, wet, frozen carbon as methane just as soon as it gets one really warm, dry, summer.
If that 70 years of industrial emissions figure isn't giving you an "oh shit moment" right now you are deluded or on serious medication. If those bogs warm up a good portion of the human race could just as well call in dead for all the good curly light bulbs are going to do them.
Put the Carbon Back
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Delay And Deny Posted 12:58 pm
21 Sep 2007
Typical, typical.
Theories always overestimate Man.
From the time of the Geocentric theory (putting Earth at the center of the Universe...sheesh) right down to AGW, people always think "We" have something to do with it.
Get some perspective...melting permafrost and bogs are more powerful than Jaguar XJ6's when it comes to greenhouse gases.
Policy? Get some lounge chairs and tanning butter and enjoy the endless summer.
John Bailo
Sutext:
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Earth Shaman Posted 3:46 pm
21 Sep 2007
Earth Shaman
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