Semiletov tells AGU that, if released, 1 percent of ESAS methane could cause runaway warming
At a press conference Tuesday at the American Geophysical Union in San Francisco, a Russian scientist who has spent the last 15 years tracking the release of methane from Siberia was asked if a huge surge he and his team detected this summer constituted “a global emergency.”
Igor Semiletov did not say no, and did not challenge the premise of the question. He first spoke of the vastness of this little-known area, an undersea shelf totaling in the range of 2 million kilometers, easily visible on photos from space, larger than Spain, France, and Germany combined. He added that he and his team, who sailed the northern coast of Siberia this summer collecting data, had taken only 5,000 measurements over the last five years. In a paper he estimated that 50 percent of this shallow shelf is now emitting methane in the summer, with “large clouds of methane bubbles observed in the water column over hundreds of square kilometers.”
Yet his struggle with the question was evident. I tracked him down later, and I asked if he felt he was the wrong person to be answering such a huge question. He admitted his discomfort, but insisted:
I am the person responsible for this research, and I think we have to tell people that something is happening now with the subsea permafrost.
Semiletov points out that geologists estimate that the amount of methane stored beneath the Siberian shelf to be on the order of 2,000 gigatons. (Keep in mind that methane is a greenhouse gas 20-times more potent than CO2, and that total carbon emissions today are in the range of eight gigatons a year.) Semiletov thinks that if just 1percent of the ESAS methane is released, it will push total atmospheric methane up to 6 parts per million, and he cites researchers such as David Archer in arguing that this would push us past the point of no return toward runaway global warming.
Leading climatologist James Hansen also gave a talk at the conference, to his usual throng of thousands, about the threat of runaway global warming and the need to phase out coal plants. He happened to mention that the global atmospheric record showed a slight fall-off in methane for 2008, so I asked him if he was less concerned about this particular threat to a stable climate. Hansen said that on the contrary, the paleontological record probably isn’t a good guide to global methane release, because “even though evidence of releases might look like spikes on a plot, they still happened over thousands of years. Human forcings are happening so fast they don’t allow for negative feedbacks.”
Hansen added that most researchers were confident that methane hydrates would remain stable because “they assume that the heat perturbation would not penetrate the frozen layers, but last summer we saw methane coming up through chimneys in the permafrost, so maybe it doesn’t take actually melting the surface to release the gas.”
This is a precise description of what the data assembled by Similetov’s team shows, along with evidence from isotope analysis that this methane is coming from deep reservoirs.
We are aware that our results showing that the permafrost is no longer an impermeable barrier to methane release have not been duplicated by other researchers at this time. But it is high time to warn people.
He stopped for an instant and smiled, before adding, “We can do nothing about it, of course.”
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