Atmosphere Journal Entry

Arctic Ice Shrinks to 3rd Smallest (October 26, 2009)

Arctic sea ice melted to its third lowest total ever recorded this summer, according to the National Snow and Ice Data Center. At its low-point in September, the sea ice covered slightly more than two million square miles.

This year's total is 400,000 square miles more ice than the record-low total seen in 2007. It's also a modest increase over last year's total. But it's still 650,000 square miles less ice than the long-term average. Even more worrisome, most of the ice is thinner, "younger" ice. About 49% of it is less than a year old and 32% is between one and two years old. Less than 20% is thicker, more stable ice at least two years old, way below the long-term average of 48%.

Meteorologists say this year's increase in sea ice is not a sign the Arctic is cooling again. The increase was due to shifting wind patterns over the Arctic Ocean that kept sea ice from reaching the warmer waters of the Pacific. The ice is expected to keep shrinking in the decades ahead with rising global temperatures. The rise is blamed on the increase in greenhouse gases in the atmosphere from the burning of fossil fuels.

Another recent study showed the Arctic was warmer over the past decade than in any other 10-year period over the past 2,000 years. The warming trend has been going on since the start of the Industrial Revolution, reversing a long cooling trend.

The changes are alarming. The Arctic's ice cap works like a gigantic air conditioner for Earth's climate control system. The glassy ice surface reflects huge amounts of sunlight back into space. As more ice melts, less light is reflected and more solar energy is absorbed by the darker ocean. The extra heat speeds the melting of the ice.