Terraforming Earth IV: The Question of Methane
Terraforming Earth is the effort to use large-scale engineering to affect geophysical processes in a way to avert radical changes to the environment -- that is, to make Earth "Earth-like" again. I touched on the idea first here, expanded on it here, and explored some of the more philosophical questions here. In all of these pieces, however, you'll note that this terraforming work is thought to be an option for some time down the road, after other solutions are exhausted. There's no argument in those three essays that we should start large scale engineering efforts now.
Today's email brought news that should make us think hard about how soon we might want to bring such efforts to bear.
Many of you sent me links to the article in today's Guardian UK newspaper (linking to a New Scientist article) outlining a "tipping point" in the Siberian arctic: the permafrost appears to be melting. This is happening due to a combination of natural arctic temperature cycles, global warming (Siberia is warming faster than any other place on Earth), and a feedback effect from melting snow -- the darker ground absorbs more heat, resulting in faster melting of adjacent permafrost. Siberian permafrost covers a million square kilometers of ground that's largely peat bog; the peat has been producing methane for centuries, but that methane has been trapped under the permafrost. With the permafrost melting, the methane would be released into the atmosphere, accelerating global warming by a substantial amount. How quickly the methane would be released remains an open question -- would it take years to release it all? Decades? A century or more? Clearly, this situation demands a great deal more study.
It's important to note that the source of this story is not a peer-reviewed, multiply-confirmed piece of research in Nature, Science or the PNAS. It's an article in New Scientist about a presentation from a group of researchers just back from Siberia. This doesn't mean that the findings are wrong, only that we should be skeptical until they've been confirmed. But that such permafrost melting would result in the release of abundant methane is not a new theory, and New Scientist notes that independent research points to methane "hot spots" already forming in the region.
For the moment, then, let's assume that the article is generally correct: the permafrost melt is getting faster, and the boggy ground beneath is releasing its pent-up methane. There are two important things to know about this situation: the amount of methane that would be released is projected to be in the multi-gigaton range -- one source says 70 billion tons, another says "several hundred" billion tons; and methane is 21 times more powerful a greenhouse gas than carbon dioxide. In essence, the release of (say) 100 billion tons of methane would be the functional heat-trapping equivalent of 2.1 trillion tons of CO2. To put that number into perspective, the total annual output of greenhouse gases from the US is about 7 billion tons of CO2 equivalent.
This is a big deal.
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