Science - December 11, 2014

Disturbing tundra makes permafrost melt faster

Text:
Joris Tielens

The subsoil of the tundra in Siberia is permanently frozen. This permafrost is a store for large amounts of carbon, which gets converted into the strong greenhouse gas methane if the ice melts. Because of the vast scale of the permafrost, this is seen as a time bomb which could speed up to climate change.

New research by researchers in the Nature Management and Plant Ecology chair group  suggests that the tundra is more vulnerable  than was first believed.  Monique Heijmans and colleagues  conducted an experiment in Yakutia in  the tundra of eastern Siberia, well inside  the arctic circle. The average temperature  there is 13 degrees below zero. In the inhospitable landscape, the researchers  removed low bushes and studied  the effect of doing so over the subsequent  years. Due to the lack of shade and  heat insulation from the bushes, the soil  warmed up in the summer and the top  layer of the underlying ice melted. Within  five years the ground therefore sank at  least 30 centimetres. In the winter more  snow stayed lying in the hollows, and in  the summer more water, leading to the  formation of small lakes. Heijmans explains  that the lakes speed up the process: ‘The snow insulates in the winter,  so the permafrost does not cool off so  much. In the summer, the dark water  causes more heat to be absorbed from  the sun, which speeds up the process.’ 


Lower house

Degradation to tundra vegetation, as is  happening in western Siberia and Alaska  due to oil and gas extraction, can therefore  set a process in motion which causes  the permafrost to melt. Heijmans: ‘A thick layer of ice at minus 13 degrees average  looks like a stable system. But it  does not take much to set off a chain reaction  which makes the permafrost  melt. Our recommendation is not to allow  any human activity within the arctic  circle.’  The Wageningen study prompted a  motion in the lower house of the Dutch  parliament during the recent debate on climate policy. In the motion, the Animal  Rights Party and the Socialist Party  called for the government to make a stand for keeping the Arctic region free  of oil and gas extraction.


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