Using the latest observational data from the European Centre for Medium-Range Weather Forecasts, a team led by James Screen of the University of Melbourne has demonstrated that the Arctic is undergoing a distinctive pattern of warming that is highly consistent with the loss of sea ice.

‘In the study, we investigated at what level in the atmosphere the warming was occurring,’ Screen said. ‘What stood out was how highly concentrated the warming was in the lower atmosphere than anywhere else. I was then able to make the link between the warming pattern and the melting of the sea ice.’

According to Screen, the increased Arctic warming is due to positive feedback between sea ice melting and atmospheric warming.

‘The sea ice acts like a shiny lid on the Arctic Ocean,’ he said. ‘When it is heated, it reflects most of the incoming sunlight back into space. When the sea ice melts, more heat is absorbed by the water. The warmer water then heats the atmosphere above it. What we found is that this feedback system has warmed the atmosphere at a faster rate than it would have otherwise.’

July 2010