How extreme will it get?
- Emissions by people cause global warming, with temperatures rising around the globe, including the Arctic.
- Soot, dust and volatile organic compounds settle down on snow and ice, causing albedo change. More heat is absorbed, rather than reflected as was previously the case. This causes accelerated warming in the Arctic.
- Accelerated warming in the Arctic threatens to weaken methane stores in the Arctic with the danger that releases will cause runaway global warming.
Could extreme weather, like the U.S. is now experiencing, also occur in the Arctic?
Well, it actually did, not too long ago. The image on the right, from the Cryosphere Today, shows air temperature anomalies in the Arctic of up to 6 °C (10.8 °F) for the month September 2007.
By how much will the sea warm up during such extreme local warming events?
This also happened in 2007. The image on the right, produced with NOAA data, shows mean coastal sea surface temperatures of well over 10 °C (50 °F) in some areas in the Arctic on August 22, 2007.
How extreme was this?
The image below, from NOAA, shows that sea surface temperature anomalies of over 5.5 °C were recorded for August 2007 in some areas in the Arctic.
Could such warming reach the bottom of the sea?
Again, this did happen in 2007, when strong polynya activity caused more summertime open water in the Laptev Sea, in turn causing more vertical mixing of the water column during storms in late 2007, according to one study, and bottom water temperatures on the mid-shelf increased by more than 3 °C (5.4 °F) compared to the long-term mean.
Another study finds that drastic sea ice shrinkage causes increase in storm activities and deepening of the wind-wave-mixing layer down to depth ~50 m (164 ft) that enhance methane release from the water column to the atmosphere. Indeed, the danger is that heat will warm up sediments under the sea, containing methane in hydrates and as free gas, causing large amounts of this methane to escape rather abruptly into the atmosphere.
Would this heat be able to penetrate sediments?The image on the right, from a study by Hovland et al., shows that hydrates can exist at the end of conduits in the sediment, formed when methane did escape from such hydrates in the past. Heat can travel down such conduits relatively fast, warming up the hydrates and destabilizing them in the process, which can result in huge abrupt releases of methane.
Since waters can be very shallow in the Arctic, much of the methane can rise up through these waters without getting oxidized.
Shakova and Semiletov warned, in a 2010 presentation, that some 75% of the East Siberian Arctic Shelf (ESAS) is shallower than 50 m, as shown on the image below. Furthermore, the ESAS region alone has an accumulated methane potential of some 1,700 Gt in the form of free gas and hydrates under the sediment, in addition to organic carbon in its permafrost.
As the methane causes further warming in the atmosphere, this will contribute to the danger of even further methane escaping, further accelerating local warming, in a vicious cycle that can lead to catastrophic conditions well beyond the Arctic.