As the Arctic summer comes to an end, focus has returned to sea-ice as it reaches its annual minimum coverage. Last year (2012), there was a record low sea-ice coverage, so scientists, the media and the public are watching closely this year.
Since 1979, when satellites started photographing the region in detail, the amount of ocean covered by ice (termed sea-ice extent) in the Arctic summer has shrunk by about a third, equivalent to 10x the area of the UK. Although there has been a consistent downward trend in minimum sea ice over this period, there is a large variation from year to year in minimum sea ice extent due to differences in weather.
In 2012, there was an extremely low sea ice extent with an additional 6x the area of the UK lost via ice melting. The reasons why 2012 was such an extreme year include: a combination of increasing melting from higher ocean and atmospheric temperatures, and poor weather conditions for sea-ice, including a large storm which swept across the Arctic breaking up the ice and aiding melting. As the ice gets thinner it becomes more vulnerable to such severe weather events.
This year (2013), the summer ice extent is larger than in 2012. Although this is not surprising to climate scientists who expect there to be such year-to-year variations in summer melt, this has led some of the media to speculate that a recovery of the ice is underway. One explanation why there is more sea-ice this year is because Arctic weather conditions have been more benign this summer, without severe storms like in 2012. However, this year’s ice extent is smaller than any year before 2007, so the long-term trend for melting in the Arctic continues.
Dr Ed Hawkins from the Department of Meteorology discussed these issues with Henry Kelly live on BBC Radio Berkshire, and in The Times newspaper.