Fueled by global warming, polar ice sheets in Greenland and Antarctica are now melting three times faster than they did in the 1990s, a new scientific study says.
So far, that's only added about half an inch to rising sea levels, not as bad as some earlier worst case scenarios. But the melting's quicker pace, especially in Greenland, has ice scientists worried.
One of the biggest wild cards in climate change has been figuring out how much the melting of the massive sheets of ice at the two poles would add to the seas. Until now, researchers haven't agreed on how fast the mile-thick sheets are thawing - and if Antarctica was even losing ice.
The new research concludes that Antarctica is melting, but points to the smaller ice sheet in Greenland, which covers most of the island, as the bigger and more pressing issue. Its melt rate has grown from about 55 billion tons a year in the 1990s to almost 290 billion tons a year recently, according to the study.