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How Arctic sea ice has retreated over the years

Retreating ice

NASA

Historically, sea ice forms every winter across the top of the planet, and covers much of the Arctic Ocean. Every summer, the ice melts a bit and retreats, only to repeat the cycle again. But since the 1980s, the Arctic sea ice is melting at a rate far faster than anyone thought, and it is already wildly, and perhaps permanently, changing the region, and the planet.

Scientists say the rapidly melting ice is raising sea level, erasing food sources and habitat, and causing waves and wind so strong they are biting off chunks of coastlines in Alaska, Canada and elsewhere.

"In general, we are losing tremendous amounts of ice from everywhere on the planet," said Tom Wagner, program manager for NASA's cryosphere research. It is happening in "Greenland, Antarctica, the small glaciers and ice caps of Alaska and Canada. And all that stuff is raising sea levels." We even appear to be losing ice in the Himalaya mountain range, he added.

Click ahead to view NASA's graphic renderings of the sea ice levels at various times. Pictured here is 1988.

2007

NASA

"Think of the Earth's climate system as a 1970's stereo, with great big knobs all over it, and that the music coming out of the speakers is climate and temperature and stuff," Wagner said. "Arctic sea ice is one of the big knobs, and we are turning it. And we don't really know how it is going to change the music."

Some of these changes are already occurring.

"We are causing tremendous erosion in Alaska because they are exposed to waves hitting their shore in areas that used to be covered in ice," Wagner said.

One indigenous community in the Arctic voted to move because their village is disappearing into the sea, from water and wave action.

2012

NASA

It is hard even for scientists to understand what is going on. The Arctic is difficult, dangerous and expensive, to get to and travel through, so there is a great deal of it that scientists have not been able to closely examine.

Plus, these changes have already arrived, and are continuing at such a rapid pace, it is difficult for scientists to even form baseline opinions about an area against which they can measure changes.

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