4 December 2008

Much more methane gas is being emitted into the atmosphere from the tundra in northeast Greenland than previous studies have shown. New figures reveal that large amounts of greenhouse gases are being emitted into the atmosphere, not just during the warm summer months, but also during the colder autumn months. Naturally, this raises new questions concerning our understanding of the Earth’s climate system. Scientists at the University of Copenhagen in collaboration with scientists from Lund University in Sweden and the National Environmental Research Institute (DMU), Aarhus University, recently presented new and surprising figures in the scientific journal, Nature.

Methane is a highly efficient greenhouse gas, and the majority of methane in the atmosphere stems from emissions from tundra areas around the world, a significant part of which come from the polar areas. So far, scientists have believed that the tundra emits most of methane gas into the atmosphere during the warm months. However, new results show that nature has a trick up its sleeve. Scientists have learned that the onset of freezing during the long autumn months also forces enormous amounts of greenhouses gases out of the tundra. The readings were made at the Zackenberg research station in northeast Greenland.

“Actually, methane emissions in September and October 2007 matched the total methane emissions during the three warm summer months,” says Charlotte Sigsgaard, research assistant at the Department of Geography & Geology, University of Copenhagen.

The figures are very surprising, and our scientists were pleased that the extended measuring period, which was enabled by the International Polar Year in 2007, has offered new input for our general understanding of the climate system and, in particular, the drastic climate changes in the Arctic regions.

“Monitoring in -20°C can be somewhat problematic, but in this case it was fantastic and quite surprising to monitor how methane emissions from the tundra suddenly increased drastically in connection with the onset of freezing at Zackenberg,” says Charlotte Sigsgaard and adds that the new figures emphasise the importance of intensifying monitoring activities in the high arctic regions.

Charlotte Sigsgaard spent a couple of cold months last autumn in the field at Zackenberg, daily monitoring, operating and using the equipment for collecting samples from the tundra. Her work may now have given science new and previously unknown pieces for the big climate puzzle.

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