claim: Previous studies have shown that weakening carbon sinks will add 0.25°C, forest dieback will add 0.11°C, permafrost thaw will add 0.9°C and increased bacterial respiration will add 0.02°C.
evidence: Farquharson and her team guess that about 231,000 square miles ( 600,000 square kilometers ) of permafrost, or about 5.5% of the zone that is permafrost year-round, is vulnerable to rapid surface thawing.