A Rhode Island-sized piece of ice shelf has shattered and separated very rapidly from the Antarctic Peninsula, forming a plume of thousands of icebergs. Recent satellite images analyzed at the University of Colorado, Boulder, show that 1,250 sq miles of the Larsen B ice shelf disintegrated over a 35-day period beginning on Jan. 31. This is the largest breakup event of the past 30 years, says Ted Scambos, a glaciologist at the National Snow & Ice Data Center at the University of Colorado.

According to studies of ice flow and sediment thickness beneath the ice shelf, the Larsen B ice shelf seems to have existed for at least 400 years.

Scientists attribute the breakup to strong regional climate warming. Over the past five decades, the average temperature of the Antarctic Peninsula has risen 2.5 °C, or 4.5 °F. Summer temperatures on the peninsula are close to freezing, and pools of meltwater form on the ice shelves, Scambos says. The water fills small cracks in the ice and exerts positive pressure on the crack tips, extending them downward.

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