Using indicator molecules, a team of researchers headed by ETH Zurich demonstrates that carbon stored in the Arctic permafrost is being mobilised in Eurasian river basins.
Arctic permafrost soils store vast amounts of carbon in the form of dead but not decomposed plant debris. Around half of the global soil carbon reservoir is stored in these permanently frozen Arctic soils. Through global warming, however, the permafrost is thawing to increasing depths, which may mobilise the carbon stored within. The amount of water drainage from rivers such as the Yenisey and the Ob in Siberia or the Kalixälven in Northern Sweden, which drain vast land areas, has also changed. Due, among other things, to a changing precipitation regime, these rivers are conducting more water away into the seas than a few decades ago, also transporting the carbon from their basins towards the sea. The main concern for scientists is that the activity of microbes or other organisms that live off organic matter and exhale CO2 could cause carbon that has been stored for thousands of years to get back into the atmosphere – and in a big way.