Jay Zwally, NASA scientist, says that the Arctic has probably reached a 'tipping point'.

"The sea ice is decreasing faster than all the models predicted," says Jay Zwally, the ice satellite project scientist at NASA Goddard.

"We not only have the warming of the atmosphere, we have a warming of the ocean that is affecting this.

It has been surprising to everybody, this decrease in area. This is a marked departure, and this is suggesting to us that maybe we are getting at this tipping point."

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