Katey Anthony (University of Alaska, Fairbanks), Novus steering committee member Michelle Mack (University of Florida), and colleagues recently published a new study in Nature highlighting the shift of thermokarst lake carbon dynamics during the Holocene epoch. Specifically, thermokarst lakes of Siberia and Alaska, which formed during the last delgaciation, shifted from serving as a carbon source (due to release of greenhouses gases during lake formation) to carbon sinks (due to carbon accumulation in deep lake sediments). In total, carbon accumulation since the last deglaciation was estimated to be ~1.6 times larger than permafrost carbon released during lake formation. Consequently, thermokarst lakes switched from a net radiative warming climate effect, to net cooling effect about 5,000 years ago. The authors estimate that 160 petagrams of Holocene carbon has been sequestered in deep lake basins throughout Siberia and Alaska, increasing the circumpolar carbon pool estimate of permafrost by over 50%. This carbon sink may, however, be vulnerable to mineralization as permafrost disappears.
The full paper can be reviewed here.
Walter Anthony KM, SA Zimov, G Grosse, MC Jones, PM Anthony, FS Chapin III, JC FInlay, MC Mack, S Davydov, P Frenzel, S. Frolking (2014) A shift of thermokarst lakes from carbon sources to sinks during the Holocene epoch. Nature. 511: 452-456