A team of Earth and Space Sciences Department of the University of Washington (Seattle) proposes to reassess sharply higher organic carbon content of the soil very high latitudes.
While inventories were previously estimated at 1 billion tonnes in the peripheral area of the Arctic desert and 17 million in the arctic desert itself, Ronald Sletten and colleagues suggest 8,7 and 2,1 billion tons respectively for these two areas .
They rely on the results of fieldwork conducted during three successive're on a sector 365 km2 northwest Greenland.
Unlike previous studies, the samples of permafrost analyzes are not limits in the top soil (the first 25 centimeters) but were levied up to a meter deep.
The researchers then was surprised to see the presence of high concentrations of organic carbon in the lower horizons of the soil.
According to them, this burial of carbon would be due to a phenomenon of "cryogenic mixing".
While the studied sector represents just over 0,01% of the area of polar areas concerned at global scale. But if the validity of the extrapolation made by the team of Dr. Sletten is confirmed, the melting of permafrost occur, for massive gas release greenhouse, positive retroaction much more dramatic than expected on global warming.
These studies were presented at the autumn session of the American Geophysical Union (San Francisco, 5-9 December).