Thursday, 5 January 2017

NZ scientist alarmed at vanishing sea ice

A Kiwi climate scientist says he's been alarmed at how much sea ice the planet's poles lost in 2016, in what was one of the hottest years on record.

Dr James Renwick of Victoria University has been tracking levels of sea ice in the Arctic and Antarctica, where, as 2017 dawned, more than one million square kilometres of ice was missing when compared with the historical average.

Renwick said sea ice extent had been more than two million square kilometres below normal every day since September 1, according to the Sea Ice Index published by the US-based National Snow and Ice Data Centre.

Over a 76-day stretch between October 13 and December 27, more than three million square kilometres of ice were missing.

Although overall ice extent had been below average at both poles, the picture in the Arctic has been much clearer and more dramatic over time.

There, the rate of loss was much more rapid - it now had 40 per cent less ice in late summer than it did in the 1980s.

Meanwhile, Antarctica overall saw around 4 per cent more sea ice in winter, up to 2014.
In the past two years, however, sea ice has been in decline around the frozen continent, with the extent falling to record lows in the last few months of the year.

In the Northern Hemisphere, the sea extent had been close to record low levels on most days in 2016, and, as winter advanced, ice extent decreased three separate times at a time ice should have been growing.

"So, after the sun went down and the Arctic ocean became dark and cold, even then, sea ice managed to melt, which is pretty remarkable."

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