Thawing permafrost likely to boost global warming

Sep 01, 2008

The thawing of permafrost in northern latitudes, which greatly increases microbial decomposition of carbon compounds in soil, will dominate other effects of warming in the region and could become a major force promoting the release of carbon dioxide and thus further warming, according to a new assessment in the September 2008 issue of BioScience.

The study, by Edward A. G. Schuur of the University of Florida and an international team of coauthors, more than doubles previous estimates of the amount of carbon stored in the permafrost: the new figure is equivalent to twice the total amount of atmospheric carbon dioxide. The authors conclude that releases of the gas from melting permafrost could amount to roughly half those resulting from global land-use change during this century.

Schuur and his colleagues refine earlier assessments by considering complex processes that mix soil from different depths during melting and freezing of permafrost, which occur to some degree every year. They judge that over millennia, soil processes have buried and frozen over a trillion metric tons of organic compounds in the world's vast permafrost regions. The relatively rapid warming now under way is bringing the organic material back into the ecosystem, in part by turning over soil. Some effects of permafrost thawing can be seen in Alaska and Siberia as dramatic subsidence features called thermokarsts.

Schuur and his colleagues acknowledge many difficulties in estimating carbon dioxide emissions from permafrost regions, which hold more carbon in the Arctic and boreal regions of the Northern Hemisphere than in the Southern Hemisphere. Data are limited, and emissions are influenced by the amount of surface water, topography, wildfires, snow cover, and other factors. Thawing, although believed to be critical, is hard to model accurately.

Some warming-related trends in Arctic regions, such as the encroachment of trees into tundra, may cause absorption of carbon dioxide and thus partly counter the effects of thawing permafrost. But Schuur and colleagues' new assessment indicates that thawing is likely to dominate known countervailing trends.

Source: American Institute of Biological Sciences

Explore further: Leave that iguana in the jungle, expert tells Costa Rica

add to favorites email to friend print save as pdf

Related Stories

Sunlight, not microbes, key to CO2 in Arctic

Aug 21, 2014

The vast reservoir of carbon stored in Arctic permafrost is gradually being converted to carbon dioxide (CO2) after entering the freshwater system in a process thought to be controlled largely by microbial ...

Recommended for you

Team defines new biodiversity metric

Aug 29, 2014

To understand how the repeated climatic shifts over the last 120,000 years may have influenced today's patterns of genetic diversity, a team of researchers led by City College of New York biologist Dr. Ana ...

Danish museum discovers unique gift from Charles Darwin

Aug 29, 2014

The Natural History Museum of Denmark recently discovered a unique gift from one of the greatest-ever scientists. In 1854, Charles Darwin – father of the theory of evolution – sent a gift to his Danish ...

User comments : 0