It has long been believed that the thawing of permafrost in the Arctic would lead to runaway greenhouse gas emissions. However, extensive analysis of data from satellites and field sensors has found no sign of this. On the contrary, permafrost areas in the far north have to date actually absorbed more carbon than they have released.
A warming Arctic has resulted in an early spring which, in tundra areas, is producing more woody vegetation cover than before. As a result, these plants are storing enough carbon to alter the balance.
“Since around 1980, the Arctic tundra has actually become a much stronger carbon dioxide sink overall,” said Prof. Kimball, one of the researchers involved.
A shift took place around the year 2000, he said. Before that, the tundra was relatively carbon neutral. Now, it’s showing “much stronger carbon uptake.”
However, not only is spring coming earlier, but autumn is staying longer. During the fall, forest areas emit more carbon back into the atmosphere than at other points in the year.
As the climate continues to warm in years to come, those late-season emissions call into question “the continued stability of northern forests as a carbon sink,” Prof. Kimball cautioned.
Scientists predict that permafrost contains two to three times the carbon in the atmosphere. In its frozen state, permafrost locks in place carbon in organic matter. When it thaws, it begins to decompose, releasing carbon dioxide and methane, both greenhouse gases.
Contrary to some concerns from years past, the release of great volumes of carbon from permafrost is no longer expected to be a sudden event, resulting in what some had termed “runaway climate change.”
https://www.theglobeandmail.com/world/article-climate-change-carbon-northern-polar-regions/