The Vanishing Arctic

Vivienne Raper

4th October, 2007

One of the most memorable parts of Al Gore’s film 'An Inconvenient Truth' was the cartoon polar bear trying to climb on the last piece of sea-ice in the Arctic, failing, and despondently swimming off into the sunset. With scientists this week reporting that autumn Arctic sea-ice coverage reached a record low this year, Al Gore’s cartoon may not be as far-fetched as it seems.

Arctic sea ice during the 2007 melt season plummeted to the lowest levels since satellite measurements began in 1979. The average sea ice extent for the month of September was 4.28 million square kilometers, the lowest September on record, shattering the previous record for the month, set in 2005, by 23 percent. The September rate of sea ice decline since 1979 is now approximately 10 per cent per decade, or 72,000 square kilometers per year. Arctic sea ice receded so much that the fabled Northwest Passage completely opened for the first time in human memory. At current rates, the Arctic is expected to be entirely free of sea-ice in summer by 2030.

Factors that contributed to this extreme decline include the fact that the ice entered the warmer weather in an already weakened state. An unusual atmospheric pattern, with persistent high atmospheric pressures over the central Arctic Ocean and lower pressures over Siberia also pumped warm air into the region and helped push ice...