Friday, 3 February 2017

New records for Antarctic sea ice

Antarctic Sea Ice Likely to Hit New All-Time Record Lows Over Coming Days

2 February, 2017
Throughout the record global heat of 2016 and on into 2017, the world’s sea ice has taken a merciless pounding.
In the Northern Hemisphere, extreme warming of the polar region pushed Arctic sea ice extents to record low daily ranges throughout the winter, spring and fall of 2016. And even today, after many months of daily record lows, sea ice in the Arctic remains more reduced (in most measures) than it has ever been for this time of year.

On the other side of the world, the story is much the same. For it now appears that the ocean region around Antarctica is about to experience an all-time record annual low for sea ice:

(JAXA Antarctic sea ice measure for all years since 1978 shows a strong challenge to the previous record low for extent set in 1997 [lower left hand corner of the graph]. With 2-4 weeks left in the melt season, the present measure is just about 170,000 square kilometers above the 1997 record low during Southern Hemisphere summer.)

Anomalous warmth, though less intense than in the Arctic zone, did finally begin to invade the austral polar region during Southern Hemisphere spring and summer (2016-2017). And since mid October, sea ice surrounding Antarctica has remained in record low daily ranges (see lower red line on the graph above). Wednesday, February 1st’s, JAXA measure of 2.42 million square kilometers of sea ice extent remaining is now just about 170,000 square kilometers above the previous record low sea ice extent set during mid-to-late February of 1997.
During this time of year, average drops in sea ice extent are around 50,000 square kilometers per day. So if all things were equal, we’d expect melt inertia to push the measure into new record low ranges over the next 3-5 days. Unfortunately, there appears to be an added impetus for melting as another blast of above average temperatures is being drawn into Antarctica underneath strong ridging features in the Southern Hemisphere Jet stream.

(Warmth building into Antarctica over the next two weeks may be the final straw that tips the near ocean region into new all-time record lows for sea ice extent. The above GFS model prediction for February 9th rendered by Climate Reanalyzer shows temperature anomalies predicted for Antarctica and the surrounding regions. Red to orange is warmer than average, blue to purple is colder than average.)

As a result, over the next week, temperatures around Antarctica and in the nearby region of the Southern Ocean are expected to average between 1.2 and 1.8 C above the already warmer than normal 1979 through 2000 average. Meanwhile, parts of West Antarctica’s coastal zone are expected to hit as high as 5-20 C above that average.
With more warmth on the way, with measures already striking nearly half a million square kilometers below previous daily record lows, and with at least two weeks remaining in the melt season, it appears likely that we are in for a new all-time record low for sea ice extent in the ocean region surrounding Antarctica. If the new record does occur, it will happen during a time when the Arctic is also experiencing daily record lows for sea ice during Northern Hemisphere winter and as the world is experiencing global temperatures in the range of 1 to 1.2 degrees Celsius above 1880s averages.

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