Antarctic meltdown? – Earth News – Brief Article

Antarctic meltdown? – Earth News – Brief Article – Statistical Data Included

Nicole Dyer

LAST MARCH, a Rhode Island-size ice chunk sheared off the northern portion of the Larsen B Ice Shelf, a massive plate of floating ice lining the eastern coast of the arm-shaped Antarctic Peninsula. The 650-ft. (220-meter) thick slab smashed into the Weddell Sea at a speed described as “staggering” by glaciologist (glacier scientist) David Vaughn of the British Antarctic Survey: “It’s hard to believe that 720 billion tons of ice sheet has disintegrated in less than a month.”

The amount of ice lost? Enough to fill about 12 trillion 10-kilogram (22-pound) bags! Larsen B is now 40 percent of its original size, having lost 3,250 [km.sup.2] (803,088 acres) of ice over a 35-day period starting last January. It was the largest single Antarctic ice shelf collapse in 30 years.

Scientists monitored the gradual decay of Larsen B over five years, but were startled by its sudden accelerated demise. The ice shelf may have existed since the end of the last major ice age, about 12,000 years ago.

Few dispute the cause of the collapse: Rapid-warming temperatures. The Antarctic Peninsula has warmed about 2.2 [degrees] C (4 [degrees] F) since the 1950s, a rate much faster than the global average. But why global warming has occurred is at the center of a fiery scientific debate: On one hand, many scientists say temperature increases are triggered by emissions of man-made heat-trapping gases like carbon dioxide released into the air by the burning of fossil fuels. In the atmosphere, the gases react with chemicals to create a shield that reflects heat back to Earth–a process called the greenhouse effect.

Others claim warming temperatures are the result of a natural climate cycle, pointing to Antarctica’s polar deserts, whose average temperatures may have cooled by about 0.6 [degrees] C (1 [degrees] F) in the past 14 years.

What’s your take on the collapse? To help form an opinion, visit the National Snow and Ice Data Web site at: nsidc.org

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