One of Siberia's largest rivers is dumping about 10% more fresh water into the Arctic today than it was some 60 years ago, thanks to the complex effects of increased snowfall, melting permafrost and changing weather.
The result is in line with predictions of how climate change is expected to alter the Arctic water cycle, and is a worrying sign in terms of maintaining important ocean currents. The more fresh water that enters the northern seas, the less dense this water becomes and the less likely it is to sink. This sinking currently helps to drive a powerful Atlantic current that keeps the climate temperate and steady. Freshening of the Arctic Ocean may already have begun to affect this so-called thermohaline circulation, but oceanographers and climate modellers are still puzzling about the magnitude and likely effects of the changes (see 'Climate change: A sea change').
Jessie Cherry of the University of Alaska in Fairbanks and her team analysed records of precipitation, snow depth and runoff in the catchment area of the Lena River, an area of more than a million square kilometres east of the Ural mountains in Siberia.
The team, including two Russian scientists, found that the average winter snow depth there has doubled to 44 centimetres from 22 centimetres in 1940. Although summers in the region have become significantly dryer, and also slightly cooler, total runoff from the Lena has increased by around 10%, they reported at the European Geosciences Union annual meeting in Vienna, Austria, on 5 April.
EDIT
http://www.nature.com/news/2006/060403/full/060403-9.html