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December 19, 2008

Defrosted

The annual meeting of the American Geophysical Union or, as I like to call it, the Doomsday Society, has just concluded. The topics of the moment were ice, as in melting, and methane, as in releasing lots of. And the methane they're talking about isn't the stuff coming out the back of the front of farm animals. It's the methane that's been trapped in the permafrost, both in the frozen tundra as well as underwater (did you all know there was undersea permafrost?). Turns out there's a lot it - as much as there is carbon in the atmosphere right now. Which would be fine and dandy, if only the permafrost weren't melting. Melting permafrost is, as Joe Romm observes, a tragically under-reported story. That's surprising since, via Romm:
  • Siberian tundra contains probably the world's largest amount of carbon locked away in the permafrost.
  • As it defrosts, much of the tundra's carbon would be released as methane, which is 20 times more potent a greenhouse gas than carbon dioxide.
  • "The year 2007 was the warmest on record for the Arctic," according to NOAA.
  • NOAA reported that methane levels rose in 2007 for the first time since 1998 (see here).
  • Scientific analysis suggests the rise in 2007 methane levels came from Arctic wetlands (see here).
  • The tundra feedback, coupled with the climate-carbon-cycle feedbacks, could easily take us to the unmitigated catastrophe of 1,000 ppm.
Now, I wouldn't run for the hills just yet. But I will say this. Whenever scientists talk about something triggering the climate "tipping point" aka "point of no return" aka "the human race's terrible, horrible, no good, really bad day," they invariably talk about a catastrophic release of all that methane.

Thanks to the Permian-Triassic Extinction Event (aka "the Great Dying") when, as I recall Wikipedia tells us, "96 percent of all marine species and 70 percent of terrestrial vertebrate species" went extinct (not to mention the fact that it was "the only known mass extinction of insects"), we have a pretty good idea what happens when there's a massive release of methane and catastrophic heating. Fun fact: many scientists now believe that all the heat in the ocean back in the Permian caused the deep ocean currents to shut down, which in turn caused a build-up of sulfides underwater that then bubbled out of the ocean as hydrogen sulfide gas (a "broad spectrum poison" Wikipedia says) which floated onto land and killed almost everything. I swear I'm not making this up. Point being, running for the hills won't really help anyway.

So forgive me a brief quake in the boots when a scientist studying underwater permafrost talks about "large clouds of methane bubbles observed in the water column over hundreds of square kilometers" - bigger than they've yet seen. This melting permafrost might explain why those methane levels rose. Combine that with the 2 trillion tons of ice lost in the Arctic since 2003 and you get some seriously bad climate mojo.

You know what? I'm scaring myself. I think I'll wrap up there. Perhaps I'll spend the holidays in the hills.

Photo by Ludovic Hirlimann used under CC license

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Anonymous Sheila said...

I remember reading an early-ish doomsday article in the New Yorker, back when people were saying "the greenhouse effect" instead of climate change and global warming. I think it was high school. At any rate, it was all about methane and permafrost and the tundra feedback loop, and it pretty much made me think there was no hope at all, 20+ years ago, and it didn't even go into fogs of acid covering the earth.

Not having heard too much about it in the years since, I sort of forgot about it, relegating it into the corner of my brain I reserve for alarmist theories that won't come to pass, and it's been gathering dust there ever since. I guess I need to take it out and brush it off, hunh?

Blogger tlaskawy said...

Well, maybe not. My sister-in-law is a paleoclimatologist - you know, like in the movies - and she pointed me to a paper by a colleague of hers. The paper said that the methane in permafrost appears to be incredibly stable and fairly impervious to catastrophic release. The stuff bubbling out now, even in the event of further warming, is a drop in the bucket atmospherically. All the evidence from the historical record suggests (at least to this guy) that the most "cataclysmic" releases of methane from permafrost in the past still occurred over thousands of years, enough time for climate feedback loops to adapt. So just hope YM mayn't V.

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