Rising temperatures is already causing the ice in the Arctic to melt. If the Arctic tundra also follows suit, it will tumble vast organic wastes into rivers heading for the Arctic Ocean, upping carbon dioxide emissions, fear scientists.

“Large amounts of organic carbon are currently stored within the permafrost. If released, they will result in an increased release of carbon dioxide to the atmosphere,” says Sofia Hjalmarsson, who submitted her doctoral thesis at Gothenburg University.

Several Russian rivers enter the Arctic Ocean, particularly in the Laptev Sea north of Siberia, including Lena, one of the world’s 10 largest rivers, in terms of its drainage basin and length.

The river water carries organic carbon from the tundra, and research by the university shows that this adds a considerable amount of carbon dioxide to the air when it is degraded in the coastal waters.

The increase in temperature in the Arctic, which has already made an impact in the form of reduced sea ice cover during the summer, may also cause the permafrost to melt.

In her thesis, Ms. Hjalmarsson has studied the carbon system in two different geographical areas: partly in the Baltic Sea, the Kattegat and the Skagerrak, and partly in the coastal waters north of Siberia (the Laptev Sea, the East Siberian Sea and the Chukchi Sea), says a university release.

The two areas receive large volumes of river water containing organic carbon and nutrients, mainly nitrogen.