July 29, 2009

Arctic CO2 Fueling Fierce Global Warming Cycle

A new European study finds that climate change is accelerating the release of carbon dioxide (CO2) from sub-Arctic peatlands, stimulating a fierce cycle of global warming.

Northern peatlands contain one-third of the Earth's soil-bound organic carbon, the equivalent of half the CO2 in the entire atmosphere.  An increase of just 1.8 degrees Fahrenheit (1.0 degree Celsius) over current average temperatures would more than double the amount of CO2 released from the peatlands, the study found.

Peat is a buildup of partially decayed vegetation found in wetlands or peatlands, which cover 2 to 3 percent of the Earth's total land mass.  Most peatlands are found in the sub-Arctic regions, but they are present in all climate zones.

The European researchers, led by Ellen Dorrepaal of the University of Amsterdam, artificially warmed plots of natural peatlands in Abisko, in northern Sweden, by 1.0 C over an eight year time period.  They found the plots released an extra 60 percent of CO2 in Spring and 52 percent in Summer over the entire period.

"Climate warming therefore accelerates respiration of the extensive, subsurface carbon reservoir in peatlands to a much larger extent than previously thought," the AFP news agency quoted the researchers as saying.

The study's findings underscore the intense sensitivity of northern peatland carbon reservoirs to climate change, and the peril of a "positive feedback" cycle in which the CO2 released into the atmosphere fuels additional global warming.

Adding to the threat is the fact that unlike the boreal forests in Russia, Canada, and Northern Europe, very little of the extra carbon released by the peatland was absorbed by additional vegetation caused by the warmer temperatures.

The researchers caution that the 38 to 100 million tons of annual surplus CO2 released by peatlands with a 1.0 C temperature increase could negate the European Union's goal of reducing greenhouse gas emissions by 92 million tons per year.

In a separate study released last month, the Australia-based Global Carbon Project found that roughly 1.5 trillion tons of carbon is stored in the Arctic and boreal regions of the world --  more than twice the amount of previous estimates.

The European study will be published Thursday in the British journal Nature.


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