Scientists’ worst fears about the impact of global warming on the Arctic Sea may be coming true sooner than expected, now that the ice sheet has reached an all-time low.

Measurements of the sea ice reveal it currently covers about 1.58 million square miles, which is less than 30% of the Arctic Ocean’s surface. By the time the summer season ends in a few weeks, the ice will likely shrink to the lowest level ever recorded.

Overall, the volume of sea ice in the summer has shrunk more than 40% since satellite tracking began in 1979, and this year saw the greatest loss in any year since then. Most of the decrease is likely due to global warming, itself the consequence of pollution and the cutting down of forests, according to scientists.

Scientists at Reading University estimate that between 5-30% of the recent ice loss has been due to the Atlantic Multi-decadal Oscillation, a natural climate cycle that repeats every 65-80 years.

NASA’s researchers attribute this year’s unusually large loss to Arctic ice not to warm weather this year, but to increased temperatures in previous years that broke down thicker ice cover.

Some experts originally predicted the Arctic Sea would become free of ice during the summer months by the middle of this century. Now, they warn it could happen within a few years, by 2015 or 2016.

“It’s hard even for people like me to believe, to see that climate change is actually doing what our worst fears dictated,” Jennifer A. Francis, a Rutgers University scientist who studies the effect of sea ice on weather patterns, told The New York Times. “It’s starting to give me chills, to tell you the truth.”

-Noel Brinkerhoff, David Wallechinsky

To Learn More:

Arctic Sea Ice Reaches Record Low, NASA Says (by Roger Harrabin, BBC News)

Arctic Sea Ice Shrinks To New Low In Satellite Era (NASA)

Satellites Show Sea Ice in Arctic Is at a Record Low (by Justin Gillis, New York Times)

As Arctic Ice Melts, U.S. Competes for Oil, Gold and other Resources (by David Wallechinsky and Noel Brinkerhoff, AllGov)

China Prepares for Ice-Free Arctic (by David Wallechinsky and Noel Brinkerhoff, AllGov)