Because Arctic sea ice floats partially submerged in the ocean, its decline does not immediately lead to rising sea levels. However, scientists say that the shrinking ice can lead to warmer ocean temperatures, which in turn can melt ice in Greenland and elsewhere that will contribute to higher waters. Some scientists now think that Arctic ice could vanish altogether by 2015.

Just as the North Korean missile launch on Sunday lent urgency to President Obama’s Prague speech on nuclear disarmament, this revelation adds weight to a meeting of international leaders in Washington to address polar warming issues. According to Secretary of State Hillary Rodham Clinton, the United States may ask the states of the Arctic Council — which includes the United States, Canada, Russia, Sweden, Denmark, Norway, Finland and Iceland — to take steps to reduce short-lived pollutants that contribute to polar warming, including methane and soot (black carbon).

As The Post’s Juliet Eilperin and Mary Beth Sheridan point out, yesterday’s measurements are the latest evidence against columnist George Will’s Feb. 15 assertion in the newspaper that sea ice is actually growing:

As global levels of sea ice declined last year, many experts said this was evidence of man-made global warming. Since September, however, the increase in sea ice has been the fastest change, either up or down, since 1979, when satellite record-keeping began. According to the University of Illinois’ Arctic Climate Research Center, global sea ice levels now equal those of 1979.

Looks like Will might have to get The Post’s ombudsman to defend him again.

Update: Reuters has a good video simulation of the shrinking Arctic ice (starting about a minute in), along with similarly bleak news coming out of Antarctica, where a major ice shelf is on the brink of breaking off.

This puts into perspective the weight of Gov. Sarah Palin’s efforts to keep polar bears off the endangered species list. Palin led her state in suing the U.S. government for classifying the bears as threatened. She argued that the listing would interfere with development in Alaska — not at all surprising, since the governor apparently has a record of supporting runaway growth with no regard for environmental impacts, according to this Salon story.

As for the fate of polar bears, another reason Palin may not support doing something about melting Arctic ice is simply that she thinks the “jury is still out” on whether global warming is caused by human activity.

I’ll have more to come from climate experts who are astonished to hear such comments on climate change coming from the governor of Alaska — an area feeling some of the worst effects of a rapidly increasing climate of anywhere in the world.