Arctic sea ice 2nd lowest on record

Warming in the Arctic shrank the ice covering the polar ocean this year to its second-lowest extent in four decades, scientists announced Monday, yet another sign of how climate change is rapidly transforming the region. 

Satellites recorded this year's sea ice minimum at 3.74 million square kilometers on Sept 15, only the second time the ice has been measured below 4 million square kilometers in 40 years of record keeping, said researchers at the National Snow and Ice Data Center.

The record low of 3.41 million square kilometers, reached in 2012 after a late-season cyclonic storm broke up the remaining ice, is not much below what researchers see today.

This year's decline was especially fast between Aug 31 and Sept 5, thanks to pulses of warm air coming off a heat wave in Siberia, according to the NSIDC. The rate of ice loss during those six days was faster than during any other year on record. Another team of scientists found in July that the Siberian heat wave would have been all but impossible without human-caused climate change.

As the Arctic sea ice vanishes, it leaves patches of dark water open. Those dark waters absorb solar radiation rather than reflecting it back out of the atmosphere, a process that amplifies warming and helps to explain why Arctic temperatures have risen more than twice as fast as the rest of the world over the last 30 years.

The loss of sea ice also threatens Arctic wildlife, from polar bears and seals to plankton and algae.