Ice falls to near record low

Ice falls to near record low
This mosaic of satellite images over the Arctic Ocean shows ice levels nearing a record low set in 2007. Acquired from the European Space Agency's radar satellite Envisat ASAR, the blue areas represent regions where ice accounts for more than 80 per cent of the sea surface. ASAR captured the high resolution images over the course of three days beginning 9 September. The satellite's radar penetrates the obscuring effects of the Arctic's frequent dark hours and thick cloud cover.

Sea ice levels have plummeted since 1979, when satellite records of conditions in the Arctic began. By the 1980s, minimum ice levels observed at the end of each summer summer had already fallen 50 per cent.

The past five years have seen the five lowest levels on record. According to the National Snow and Ice Data Center in Boulder, Colorado, this year's minimum ice extent is 4.33 million square kilometres, just 160,000 square kilometres above the 2007 level. However, a team of researchers at the University of Bremen in Germany have come up with a separate estimate using a microwave sensor on board NASA's Aqua satellite. They suggest sea ice extent may have shrunk beyond 2007's minimum extent to an all-time low.