BBC News is reporting on a disturbing study presented this week at the American Geophysical Union meeting that shows the polar ice sheet is melting more quickly than anyone imagined. This past summer, the sheet retreated to a size of 4.13 million sq kilometers, the smallest in recorded history. You can see a flash animation of the ice cap's size over the past 27 years with the BBC story. The scientists who worked on the study say this new data means the ice cap might melt entirely by summer 2013. [BBC News]