Saturday, March 6, 2010

Arctic permafrost again

I blogged on Arctic permafrost before.

Now Yglesias has discovered the latest study. Here and here.

Permafrost under the Arctic ocean seems to be giving way, allowing for the release of methane gas--in its potential effects, a more powerful greenhouse gas than CO2. Already, according to the video, the concentration of methane in the atmosphere above the Arctic seems higher than at any time in the last 400,000 years. Yglesias takes some things for granted that the scientists involved are at least somewhat uncertain about:

1. Are rising temperatures the only possible reason for the permafrost to break up? There are people who think the reason for Arctic ice reaching a low point in Summer 2007 was that it was moved by ocean currents and wind to a warmer place, rather than melting in a colder place. What are the factors at work below the surface?

2. As the methane concentration increases, is there only one possible or likely outcome? Yglesias refers to a "feedback loop," implying that warmth causes more various results which then multiply the rate of warming. But what if it's not a closed system, and there are ways for greenhouse gases to be dissipated? Some people who agree that warming is happening say that there is no evidence of the feedback or multiplying effect. (Joanne Nova h/t Richard North).

3. Even if Arctic permafrost is melting, does that indicate global warming? The article in the Guardian that supposedly shows there is a "human fingerprint" on many different changes in climate, includes a map. On the map, Alaska and the nearby Arctic is a uniquely hot spot; much of the Northern hemisphere is warm, but not as warm as Alaska; much of the southern hemisphere is cool, but no area is as cool as Alaska is hot. One can generalize at a very high level and say there is more warming than cooling, but why would there be so much variation if there is one clear global trend? h/t Lubos and Bishop Hill.

No comments:

Post a Comment