Thaw in Greenland threatens new ice age - This week's big chill could prove a taster of winters to come

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Thaw in Greenland threatens new ice age - This week's big chill could prove a taster of winters to come

Paul Brown, environment correspondent Saturday January 11, 2003 The Guardian

The snowfalls of the past week may be just a taster of what is to come, if the latest predictions from scientists are correct. The amount of ice melting from the surface of the Greenland ice sheet broke all known records last year, threatening a rapid rise in sea levels and a return of very cold winters to Britain because of a slowing down in the Gulf Stream.

Already the Gulf Stream, which bathes the west coast of Britain in warm water from the Gulf of Mexico and keeps the country much milder than normal for such northern latitudes, is slowing down. Even greater melting of the Greenland ice could shut off the currents altogether, allowing depressions to dump snow rather than instead of rain in Britain and leading to a much colder continental climate, as has been experienced in the past week.

As happens on the eastern seaboard of Canada, which on the same latitude, the sea could freeze and snow lie for weeks or months instead of a day of two.

Last year large areas of the Greenland ice shelf, previously too high and too cold to melt, began pouring billions of gallons of fresh water into the northern Atlantic. Melted water trapped between the ice and the rock beneath is causing an acceleration of glaciers breaking off in huge chunks and increasing the number of icebergs.

According to scientists at the University of Colorado a very dramatic melting trend has been in progress since 1979. Extreme melt years were 1991, 1995 and 2002.

-- Anonymous, January 11, 2003

Answers

Climatologist Konrad Steffen, a professor of geography at Colorado, said a change in the Greenland climate towards warmer conditions would lead to an increase in the rate of sea level rise, mainly due to the dynamic response of the large ice sheet rather than just the surface melting.

"For every degree increase in the mean annual temperature near Greenland, the rate of sea level rise increases by about 10%," Professor Steffen said. Oceans are now rising by a little more than half an inch every 10 years.

Both sea ice and glacier ice cool the earth, reflecting back into space about 80% of springtime sunshine and 40% -50% during the summer melt. But winter sea ice cover slows heat loss from the relatively warm ocean to the cold atmosphere. Without large sea ice masses at the poles to moderate the energy balance, warming escalates.

-- Anonymous, January 11, 2003


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