The Arctic: A greenhouse gas hotspot?
Vast amounts of organic carbon are stored in Arctic permafrost soils and in the seabed of the Arctic shelves. In a warming world, some of this carbon might be degraded as carbon dioxide or methane and amplify the terrestrial greenhouse effect. How fast and how strong is this climate feedback? Earth System Model simulations predict increasing carbon losses from thawing permafrost during this century. However the global context, Arctic surface-atmosphere fluxes of these gases are currently still very modest. Longer-term comprehensive measurements in north-eastern Siberia and Alaska over permafrost indicate that the local hydrological regime during summer time thaw determines the budget of greenhouse gases, but also the local energy balance. The micro topography of permafrost landscapes constitutes thus a critical parameter controlling Arctic greenhouse gas emissions.