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
bogs, please explain
I'm a swamp Yankee growed up in Connecticut and whew, the methane and sulfide was intense at low tide. Sometimes the methane would glow at night, the stuff of ghost stories.
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
Muskeg, Peat, Permafrost......
There are huge areas of cold climate bogs that are heating up.
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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WWAGD?! Posted 12:58 pm
21 Sep 2007
Overestimating Man
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
Time
Earth Service says that 28 thousand ago,the grid revv from the system explosion created the first stock of oil on the planet from all of the plants turning to a goo at the oven temperature over 200 degrees on the planet.Oil(Petroleum) is vegetable oil,it just is.Most of that oil is sour by now. !14 thousand ago,that system explosion remnant field came back,(On the round) That is our sweeter oil.The core evidence and other evidence of warming and cooling periods timing is wrong on the Neo-science side.Old papas know the proper science and timing,I assure you.And you know 28,then 14 and now is a progression for you science buffs to ponder and process what I have shared on this Blog and others about the grid revv we are experiencing now that is causing our warming.Simple,really. And those of you who poo poo the Mayan calendar information on the timing of cycles that ends in 2012 should reassess your statements.But I fear that you will insist we ruin our economy and allow our"fearless Leaders" to spend their time worrying about things they cannot change and not worrying about things they should. BUSINESS AS USUAL. This old "papa" also says you do have a choice,if you assert it.
Earth Shaman
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