In an update to my last post on Arctic methane, I linked to a Swedish team blogging their research on the Yakov Smirnitsky, a Russian vessel currently cruising the seas to the north of Siberia. The most recent post there is fascinating, but the Google translation rather difficult to follow, so I asked Magnus Westerstrand, who first drew my attention to the blog at Eli’s place, if he could tidy up the translation. And he did, overnight. Thanks Magnus, have a schnapps on me. Here are some extracts [full text at Magnus’ blog]:
At around 110 degrees easterly longitude, when we where wrestling with drift ice in western Laptev Sea, we discovered two new areas where methane concentrations in both the water and in the air above clearly exceeded the normal methane concentration in Arctic.
The blogger, Ã–rjan Gustafsson, then goes on to describe how the methane deposits were formed, and how the gas might now be escaping.
Big methane reservoirs are located in the sea bed both in and under a layer of permafrost. This permafrost layer where created in this region during the latest â€œice ageâ€ and some have thought that this frozen layer stops the methane gas from leaking out in the sea water and further to the atmosphere. The sea level at the last ice age where much lower then the present level and the Siberian costal sea where at that time above sea level. When the glaciers melted the sea level rise and the frozen land was flooded.
To release the trapped methane the permafrost have to thaw this could happen in several ways.
1. The overlaying sea water warms the sediment slowly.
2. Geothermal heat â€“ in fault zones (cracks in the earths crust).
3. River plumes gets longer â€“ warm river water thaws up an area of permafrost.
Process 1 and 3 could accelerate because of the greenhouse effect, warmer river water, increased discharge and higher temperature in the water close to land along the east Siberian coast. Data from NOAA show that the average temperature during mars-may in the region have been up to 4 degrees warmer in the beginning of 2000 compared to the last three decades at the end of 1900.
Semiletov suggests that one reason that it might not have been a degaussing earlier is the extreme slow thawing of the permafrost in the frozen sea bed. Now the anthropogenic warming of the northeast Siberian area have lead to increased river discharge and higher temperature on both river water and other costal water which could contribute to an accelerated erosion of the permafrost layer.
This is important research, and we are privileged to be able to learn first hand what’s going on. Thanks again, Magnus. That’s another good night’s sleep you’ve ruined… 😉