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Decline of Arctic sea ice increases

For the fourth consecutive year, scientists using satellite data have tracked a stunning reduction in arctic sea ice at the end of the northern summer. If current rates of decline in sea ice continue, the summertime Arctic could be completely ice-free well before the end of this century.

Arctic sea ice extent, or the area of ocean that is covered by at least 15 percent ice, typically reaches its minimum in September, at the end of the summer melt season. On September 21, 2005, the five-day running mean sea ice extent dropped to 5.32 million square kilometers (2.05 million square miles), the lowest extent ever observed during the satellite record

This decline in sea ice amounts to approximately 1.3 million square kilometers (500,000 square miles). This is an area roughly equivalent to twice the size of Texas.

Having four years in a row with such low ice extents has never been seen before in the satellite record. It clearly indicates a downward trend, not just a short-term anomaly.

Since 2002, satellite records have also revealed that springtime melting is beginning unusually early in the areas north of Alaska and Siberia. The 2005 melt season arrived even earlier, beating the mean melt onset date by approximately 17 days, this time throughout the Arctic

In addition, arctic temperatures have increased in recent decades. Compared to the past 50 years, average surface air temperatures from January through August, 2005, were 2 to 3 degrees Celsius (3.6 to 5.4 degrees Fahrenheit) warmer than average across most of the Arctic Ocean

posted by: kyawoo at 21:19 | link | comments |
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