Sea ice is frozen sea water that waxes and wanes in response to the cooling and
warming of the Arctic throughout the year. The ice pack reaches its greatest extent
at the end of the winter, during March, and its lowest point at the end of the
summer, usually in mid-September. This point is known as the sea ice minimum.
Since the early 1970s scientists have been using satellites to monitor the amount
of Arctic sea ice present throughout the year. Data suggests that during this period
the amount of sea ice in the Arctic has decreased by around 3% every ten years but,
worryingly, they have discovered that the rate of melting has increased significantly
in recent years.
The lowest ever sea ice minimum was in 2007, when the Arctic covered 4.13 million square kilometres on September 16th. The 2011 minimum was the second lowest on record and scientists are now suggesting that the extent of summer sea ice in 2012 could reach a new low.