Frozen soil, atmosphere warmed up
By Denis Delbecq • December 5th, 2008 in 11:50 · Category: Actuality
Reality sometimes takes amazing positions. While they often recall the programmes of methane caused by the thaw of the boreal soil, researchers show that the Nordic marshes also liberate some gas when they freeze, in autumn.
The humid lands of high degrees of latitude are an important source of programme of methane in the atmosphere. A consequence of intense bacterial activity in soil. A powerful gas with greenhouse effect (twenty times more than the carbon dioxide) which contributes to the warming of climate. Until now, the seasonal observations of these boreal programmes did not stick with models. Jobs of an international team published this week could well explain this divergence (1).
Six rooms of measure were installed in the valley of Zackenberg, north of Greenland, who measures every hour the content of natural gas at the level of the soil, as well as several parametres (temperature of the soil in three depths, etc.) . Usually, these instruments are disassembled at the end of August. But thanks to the international Polar year, the research station of Zackenberg remained opened two months more in 2007. As planned, the programmes of methane went down at the beginning of September. But at the beginning of October, at instant or the temperature of the soil went past again under the bar of 0°C, some methane splashed back, during some days, in strong quantities. One of the rooms even noticed a peak of 112 milligrammes of gas an hour and square metre, a record for a soil of tundra, explain the researchers. On average, the rhythm per hour of the rejections of methane was four times as high the October first half, as it was it during the summer peak of July!
The explanation of this phenomenon remains to find. The researchers offer a hypothesis: as the methane is not soluble in the water and remains present in the humid soil under forms of bubbles, these last would be evicted by the training of ice crystals.
(1) Sweden, Denmark, the United States, the Netherlands. Jobs published in the edition of Nature of December 4th, 2008.
Article read 1,604 times. Tags:climat, greenhouse effect, methane, tundra
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