Why is the Arctic warming faster than the rest of the world? One explanation refers to the release of methane from permafrost-frozen soil. Methane retains heat vastly more than carbon dioxide, the Greenhouse gas that we worry about most. Considerable research has been done on the rising temperatures of Arctic soil, especially in Siberia, a large part of the world’s carbon is located. However, there is also permafrost at the bottom of the Arctic ocean, whence comes much of the methane now being emitted.1
Methane has been escaping from the Arctic Ocean for thousands of years, and not enough research has been done yet to predict the duration of this process. Some say we have hundreds of years to solve the problem, while others say that it is happening quickly and may result in a few big explosions that push us past the tipping point toward calamity.
Apparently, large quantities of methane are being held down by an undersea permafrost “lid” that can perforate and release plumes of methane. Where the ocean is deep, this methane is absorbed without reaching the surface or the atmosphere. But the East Siberia Sea is extremely shallow, and there one can see plumes of methane bubbling to the surface, where it can be set on fire. (Indeed, it would be preferable to burn it all than let it escape as gas, since the product of burning it is CO2, which retains heat less than methane.)
Other studies report that much of the methane is coming from the undersea permafrost itself. Yet another recent study asserts that most of these plumes contain methane from a single large reservoir under the Laptev Sea.2
Finally, a new report shows that the amount of methane being released at any moment is determined by the moon! The moon controls tides, and when the tide is high, the extra water holds the undersea gas down, while low tide reduces the pressure so that more methane is released.3 The authors of this paper speculate as to whether the extra ocean depths that will result from global warming will have one beneficial side effect: limiting methane reduction. If so, this may help to offset what in other respects will be catastrophic.
See the review of Peter Wadhams’s book, A Farewell to Ice on page 28, this issue.
1 Savedeh Sara Sayedi et al, “Subsea permafrost carbon stocks and climate change sensitivity estimated by expert assessment,” Environmental Research Letters, Dec. 22, 2020.
2 Bob Yirka “Testing waters of East Siberian Arctic Ocean suggests origin of elevated methane is reservoir located in Laptev Sea,” March 2, 2021. phys.org/news/2021-03-east-siberian-arctic-ocean-elevated.html
3 Nabil Sultan, Andreia Plaza-Faverola, Sunil Vadakkepuliyambatta, Stefan Buenz and Jochen Knies, “Impact of tides and sea-level on deep-sea arctic methane emissions,” Nature Communications, 9 October 2020.