James Hrynyshyn is a freelance science journalist based in western North Carolina, where he tries to put degrees in marine biology and journalism to good use.
If not genuinely good news, then at least it's not bad news. I'm referring to a paper out today in Science (Vol. 321. no. 5896, p. 1648) that describes 700,000-year-old permafrost in the Arctic. It's an optimistic report because, if the permafrost has survived the last few ice ages, which come and go every 100,000 years or so, then they stand a good change of surviving the next few decades during which polar regions are expected to get unusually warm. And we want them to survive, because if they melt, they will release their massive carbon reserves in one of those nightmare positive-feedback-loop scenarios that climatologists worry about.
Ancient Permafrost and a Future, Warmer Arctic by a team of Canadian scientists led by Duane G. Froese of the University of Alberta in Edmonton concludes that the permafrost they found
represents the oldest ice known in North America and is evidence that permafrost has been a long-term component of the North American cryosphere. Importantly, this finding demonstrates that permafrost has survived within the discontinuous permafrost zone since at least the early-Middle Pleistocene. This age range includes several glacial-interglacial cycles, including marine isotope stages 5e and 11, both considered to be longer and warmer than the present interglaciation... [suggesting that] permafrost and associated carbon reservoirs that are more than a few meters below the surface may be more stable than previously thought.This doesn't mean that all the permafrost will survive expected warming. There are many factors to consider, including the ground cover and the pace of warming. But at least now we know that it is possible that those carbon reservoirs have a chance of staying below ground for a bit longer than we once though, instead of rapidly off-gassing into the atmosphere, where they were produce only more warming, which would melt more permafrost and so on.
Eventually, if we don't get the climate under control, even the most stubborn ice will melt, of course. And some scientists suspect there could be twice as much carbon locked in permafrost than there is in the atmosphere.So this isn't cause for relaxing. Just a welcome bit of not-so-dismal news from the climate front.
D. G. Froese, J. A. Westgate, A. V. Reyes, R. J. Enkin, S. J. Preece (2008). Ancient Permafrost and a Future, Warmer Arctic Science, 321 (5896), 1648-1648 DOI: 10.1126/science.1157525
Environment
Comments
To the pesimist this means that we have 700,000 years worth of methane stored there and no idea what will happen if we pass the threshold where it melts. If it had melted during previous interglacials we could have put an upper bound on the effect.
Posted by: Thomas | September 19, 2008 2:34 PM
Just a minor caveat. Atmospheric CO2 levels during MIS 5e and 11 stayed below about 310 ppm. Today we're at 385 ppm.
The fact that the permafrost survived 5e and 11 does not necessarily mean it will survive a prolonged period of the warmth that would result from stabilization at modern CO2 levels. Fortunately it seems there's a lag of several centuries between reaching a certain CO2 level and reaching the corresponding global warmth.
Posted by: llewelly | September 19, 2008 2:41 PM
Bad may often include good, and vice versa. If the permafrost starts to go the areas available for agriculture in Canada and Russia should increase. This could offset some of the losses in Africa and Australia.
Posted by: LKF | September 19, 2008 10:36 PM