clipped from www.foxnews.com

An already relentless melting of the Arctic greatly accelerated this summer, a warning sign that some scientists worry could mean global warming has passed an ominous tipping point. One even speculated that summer sea ice would be gone in five years.

Greenland's ice sheet melted nearly 19 billion tons more than the previous high mark, and the volume of Arctic sea ice at summer's end was half what it was just four years earlier, according to new NASA satellite data

2007 shattered records for Arctic melt in the following ways:

552 billion tons of ice melted this summer from the Greenland ice sheet

A record amount of surface ice was lost over Greenland this year

Alaska's frozen permafrost is warming

White sea ice reflects about 80 percent of the sun's heat off Earth

Earth has hit one of his so-called tipping points

"At this rate, the Arctic Ocean could be nearly ice-free at the end of summer by 2012, much faster than previous predictions."