Monday, May 08, 2017
The Warming Arctic Adding More CO2 And Methane
Think of it this way - permafrost, methane emissions; tundra, CO2 emissions. We've known for some time that melting permafrost in the Arctic is leading to the release of troubling volumes of the powerful greenhouse gas, methane. Now the focus is on the tundra and the release of the less-powerful but more persistent greenhouse gas, CO2, carbon dioxide.
A new study of Alaskan tundra reveals how CO2 release is accelerating due to the warmer Arctic climate. The tundra is now freezing later and thawing earlier.
Measurements of carbon dioxide levels taken from aircraft, satellites and on the ground show that the amount of CO2 emitted from Alaska’s frigid northern tundra increased by 70% between 1975 and 2015, in the period between October and December each year.
Researchers said warming temperatures and thawing soils were the likely cause of the increase in CO2 at a time of year when the upper layers of soil usually start freezing over as winter sets in.
In the Arctic summer, the upper level of soil, which sits above a vast sheet of permafrost that covers much of Alaska, thaws out and decomposing organic matter starts to produce CO2. From October, colder temperatures help freeze the soil again, locking up the CO2.
Alaska’s warming autumns and winters are altering this process. Whereas soils 40 years ago took about a month to completely freeze over, the process can now take three months or longer. In some places in the state, the soil is not freezing until January, particularly if there is a layer of insulating snow.