Arctic sea ice melting at near record rate


SEA ICE cover at the North Pole continues its inexorable melt-down, shrinking to a near record extent, according to new satellite data.

A related study also shows that the permanent ice cap over the Arctic is also thinning rapidly.

Data released yesterday by the National Aeronautics and Space Administration (Nasa) and the US National Snow and Ice Data Centre in Boulder, Colorado, shows that ice over the Arctic continues to disappear at a startling rate.

A Nasa satellite has tracked the extent of wintertime maximum sea ice cover since 1979. Maximum ice cover was reached this year on February 28th, extending to 15.15 million sq km.

This was the fifth lowest ice extent on record, Nasa pointed out, adding that the six worst years for Arctic ice cover have occurred in the past six years.

The data also showed that just 10 per cent of the wintertime cover is older, thicker ice that tends to survive through the summer. Several decades ago this figure was 40 per cent.

This older ice is also rapidly thinning. In another study released yesterday, Nasa researchers in California used satellite data to reconstruct ice thickness from 2005 and 2006. The older, thicker ice is declining and being replaced by thinner ice that is vulnerable to summer melt. This in turn served to hasten ice loss as the sea water warmed, the researchers said.

It has been a bad few days for the Earth’s polar ice caps. Satellite images of the Antarctic Peninsula taken last Friday by the European Space Agency showed that the vulnerable Wilkins Ice Bridge has finally snapped.

The 25-mile (40km) long strip of floating ice is believed to hold the larger Wilkins Ice Shelf in position. The British Antarctic Survey reported that the ice bridge had snapped at its narrowest point, where the bridge was no more than 500m across.

The initial break-up released a flotilla of small icebergs that have begun drifting away from the peninsula. More of the Wilkins shelf is now expected to break up, although the loss will not immediately add to a global sea-level rise.

The programme manager for the Environmental Protection Agency’s climate change unit, Dr Ken Macken, yesterday expressed concern at the continuing loss of sea ice in the Arctic. “The results confirm the continuing seriousness of climate change as a global issue, and underline the need to reach an international agreement in Copenhagen later this year.”

The data shows that climate change has not gone away, according to Oisín Coughlan of Friends of the Earth. The current focus on the global economic crisis was understandable “but this is a signal there is a much bigger crisis to be tackled”.

“That is really frightening,” said Tony Lowe of Friends of the Irish Environment. Reduced ice cover was speeding up the heating process because the sea absorbs more solar radiation than ice.