Journal of Geophysical Research: Biogeosciences
© 2013 American Geophysical Union
Impact Factor: 3.021
ISI Journal Citation Reports © Ranking: 2011: 21/170 (Geosciences Multidisciplinary)
Online ISSN: 2169-8961
Associated Title(s): Journal of Geophysical Research
High-resolution peatland photos show change with global warming
As global average temperatures rise, vast tracks of peatland currently encased in permafrost will be affected. As the ground thaws, peatlands will evolve in either of two directions. Along one path, land that was previously propped up by supportive permafrost subsides, forming a shallow basin that fills with water-a thermokarst lake. In the new lake, peat undergoes anaerobic bacterial decay, releasing methane to the environment. Alternatively, permafrost thawing can result in lake drainage. In the drained lake beds fen vegetation and mosses can grow, drawing down atmospheric carbon dioxide levels. The prevalence of these two processes, and their relationship with changing temperatures, remains an important question in understanding the consequences of permafrost thaw on the global carbon cycle. Using high-resolution satellite imagery and aerial photography stretching back to the 1950s, Sannel and Kuhry (2011) track the transformation of three permafrost peatlands: a Canadian and a Russian site with relatively cold ground temperatures and a Swedish peatland with permafrost temperatures close to 0oC. The authors found that as winter precipitation, average atmospheric, and average ground temperatures increased throughout the study period, the Canadian and Russian peatlands saw small changes in lake extent. However, the Swedish site had 7.6% of its lake area overgrown by vegetation per decade, along with the formation of some small new lakes. The authors suggest that there is a threshold air temperature, between -5oC and -3oC, above which temperature and precipitation changes begin to significantly affect peatland behavior.