41.   Four massive icebergs broke away from the ice shelf in April and May of last year.

42.   Greenpeace also predicted the likely collapse of the Larsen B ice shelf in Antarctica.

43.   Greenpeace sent two helicopters from the Arctic Sunrise over Larsen B on Wednesday and reported that the surface of the ice shelf is riven with cracks and deep fissures.

44.   He said scientists still know too little about the behavior of Antarctic ice sheets to predict whether these ice shelves will remain intact for decades or centuries.

45.   Huge chunk of ice shelf breaks off.

46.   Ice shelves are thick plates of ice, fed by glaciers, that float on the ocean around Antarctica.

47.   Ice shelves are floating plates of ice that are still attached to continents, which form when large glaciers flow toward the ocean in polar areas.

48.   Ice shelves are floating masses of ice that extend out from land glaciers.

49.   In a recent paper, glaciologists David Vaughan and Chris Doake said ice shelves on the peninsula were starting to retreat south as temperatures continued to increase.

50.   If that warming starts melting much larger ice shelves in the main part of Antarctica, environmentalists and scientists worry that catastrophic environmental changes could result.