Scientists say the amount of ice in the Arctic Ocean shrank to an all-time low this year, smashing old records for the critical climate indicator.
The ice cap at the North Pole measured 1.32 million square miles on Sunday. The previous low was 1.61 million square miles in 2007. Records go back to 1979 based on satellite tracking.
Ice in the Arctic melts in summer and grows in winter, and it started growing again on Monday. National Snow and Ice Data Center scientist Walt Meier says man-made global warming has melted more sea ice and made it thinner.
Meier says in the 1980s, summer ice would cover an area slightly smaller than the Lower 48 states. Now it is about half that size.