Scientists warn Arctic sea ice is melting at its fastest rate since records began

By Steve Connor, Science Editor
The Independent
Wednesday, 15 August 2007

The sea ice of the Arctic will melt further and faster than at any time since records began nearly 30 years ago, according to the latest data collected by a satellite survey of the polar region.

Scientists warned yesterday that the sea ice is already approaching the record minimum set in September 2005, even with a further month of the summer melting season still remaining.

This year has seen one of the most rapid rates of sea ice melting, which began in spring after one of the most disappointing winters for ice formation. "Unless something unusual happens we're definitely on track for a record loss of sea ice. We're on track to shatter all records," said Mark Serreze, an Arctic specialist at the US National Snow and Ice Data Centre at Colorado University in Denver. "The rates of sea ice loss this year are really rather remarkable. Some of the daily rates of loss are the biggest we've ever seen. Things are happening really fast," Dr Serreze said.

The area covered by Arctic sea ice has been monitored by American satellites since 1979. Sea ice, which floats on the surface of the ocean, naturally expands in surface coverage each winter and recedes in summer, but there has been a significant overall loss recorded during the past 27 years.

The rate of loss also appears to have accelerated since 2002 and this year has seen one of the fastest melt seasons on record. In July of this year, more sea ice melted than for any month on record. The surface area covered by the ice in July was 3.13 million square miles, about 347,492 square miles below the area recorded for July 2005 - an area seven times the size of England.

"Unless conditions change in an unprecedented way, the Arctic will continue to lose ice for at least another month," said the National Snow and Ice Data Centre. "At this point in the 2007 melt season, this much is already clear: the Arctic is experiencing an unprecedented sixth consecutive year with much less sea ice than normal, and it looks like this year's sea ice-melt season may herald a new and steeper rate of decline," it added.

Some computer models used by the UN's Intergovernmental Panel on Climate Change predict the Arctic will be virtually ice free by the summer of 2070. However, other computer models suggest that the year of an ice-free Arctic summer could come as early as 2030 or 2040.

Dr Serreze said that even these pessimistic predictions may have overestimated the resilience of the Arctic sea ice. He said that we may have already reached the tipping point when there is a rapid disintegration. "The big question is whether we are already there or whether the tipping point is still 10 or 20 years in the future. My guts are telling me we may well be there now," Dr Serreze said.

Most polar specialists agree that as more ice is lost in summer, the Arctic is liable to heat up faster than normal as a result of a positive feedback in the climate - instead of solar energy being reflected from the surface of the white ice, it is absorbed by the open, darker ocean, leading to even more melting of the ice.

The Arctic is already heating up at a faster rate than many other parts of the globe. While average temperatures on Earth rose by about 0.6C since 1900, the regional temperatures of the Arctic have risen by 2C to 3C.

Polar bears, which rely on sea ice to hunt for seals in summer, are already showing signs of malnutrition because they have to swim further between ice floes. Scientists believe the species could quickly go extinct if there is no sea ice at all in summer.

Paradoxically, the loss of sea ice will give Arctic countries such as Russia, Denmark, Canada, Norway and the US easier access to the parts of the seabed that are thought to be rich in oil and gas - the same fossil fuels that have exacerbated the global warming that has caused the sea ice to melt in the first place. "It's really rather disappointing when we talk about 25 per cent of the world's oil and gas reserves being under the Arctic when the loss of sea ice is the reason why we can get to it," Dr Serreze said.

In addition to record melting of sea ice in summer, the past two winters have seen a failure of sea ice to reform to the extent recorded in previous winters. This has meant that there is less sea ice in spring, and a greater chance of record summer ice loss.