by EditorDavid on (#6W8X5)
The Washington Post reports that after months of polar darkness, the extent of sea ice blanketing the Arctic this winter "fell to the lowest level on record, researchers announced this week... the smallest maximum extent in the 47-year satellite record, according to the National Snow and Ice Data Center. "Since then, the ice has already begun to melt again." "Sea ice is acting like the old canary in the coal mine," Dartmouth University geophysicist Don Perovich said. "It's saying loud and clear that warming is occurring...." In the summer, when the sun's radiation shines down on the Arctic for 24 hours a day, the ice acts as a shield, reflecting more than half of the light that hits it back into space.... With so little sea ice in the Arctic this year, more sunlight will be able to reach the open ocean, which absorbs more than 90 percent of the radiation that hits it. This will further warm the region, accelerating ice melt and exposing even more water to the light. This feedback loop helps explain the rapid warming of the Arctic, and it is expected to lead to a complete lack of summer sea ice in the region within decades, [said explained Melinda Webster, a sea ice scientist at the University of Washington]. The consequences would be dire for seals, polar bears and other wildlife, which depend on a stable sea ice platform to birth their young and hunt for food. It would also expose miles of coastline to pounding ocean waves, accelerating the erosion that threatens to tip some communities into the sea. But the effects will also be felt in places far from the poles, Perovich said. Studies suggest that a complete loss of Arctic sea ice would raise global temperatures as much as adding a trillion tons of carbon dioxide to the atmosphere. Changes in the Arctic could also affect the jet stream, the river of winds that flows through the upper atmosphere, contributing to more extreme weather around the globe. "What happens in the Arctic doesn't stay in the Arctic," Perovich said. Earlier this year sea ice also fell 30% below the amount typical in the Antarctic prior to 2010, the researchers report. The total amount of sea ice on earth has now reached an all-time low, declining by more than a million square miles (2.5 million square kilometers) below the pre-2010 average. "Altogether, Earth is missing an area of sea ice large enough to cover the entire continental United States east of the Mississippi."Read more of this story at Slashdot.