Something crazy is happening at the poles; satellite pictures show just what...

Something crazy is happening at the poles; satellite pictures show just what is wrong

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There are some really crazy things going on in the polar regions. The Arctic and Antarctic regions together have lost about 3.76 million square kilometres of sea ice as of December 4. This is more than the total area of India, or two Alaskas! Global warming is real. The poles are melting.

This animation from NASA’s Goddard Centre shows the Arctic sea ice age for the week of the minimum ice extent for each year, depicting the age in different colors. Younger sea ice, or first-year ice, is shown in a dark shade of blue while the ice that is four or more years old is shown as white. A color scale identifies the age of the intermediary years. A bar graph displayed in the lower right corner quantifies the area covered by the ice in each age category on the day of the annual minimum. In addition, memory bars shown in green portray the maximum annual value for each age range seen since Jan. 1, 1984, on the day of the annual minimum.

So far while Antarctica was not so much affected by global warming, and sea ice had in fact tended to expand in recent years, now it comes out that Earth’s southern tip is also losing ice. And steadily.

To quote Mark Serreze, director of the US National Snow and Ice Data Centre (NSIDC), “There are some really crazy things going on.” 

Why the poles are melting

Arctic ice index
The pink line shows the 1981 to 2010 median extent for the month. The black cross indicates the geographic North Pole. Credit: National Snow and Ice Data Center

European Space Agency’s (ESA) Cryosat satellite revealed on December 2 that Arctic ice freeze is slowing down and are currently at record lows. It shouldn’t be surprising given that temperatures in the Arctic region rose 20 degrees Celsius above normal in November, and 2016 is likely to be the hottest year recorded ever.

arctic-ice-levels
Monthly November Arctic ice extent for 1979 to 2016 shows a decline of 5.0% per decade. Credit: National Snow and Ice Data Center

Data analysis from NSIDC shows that Arctic sea ice for November 2016 was 9.08 million square kilometres, the lowest November in the satellite record. This is 800,000 square kilometers less than November 2006, the previous lowest November, and 1.95 million square kilometers below the 1981 to 2010 long-term average for November.

What Serreze’s team finds crazy is that in November this year the sea ice might have shrunk at the exact time of year that it should actually be increasing.

The sleeping elephant is beginning to stir

ice-anomaly-antarctica
This map of sea ice concentration difference from
average for November 2016 shows very low ice
in Antarctica. Credit: National Snow and Ice
Data Center

While scientists had been resigned to the fate of Arctic melting, the Antarctic had so far held up and was seen to be adding ice in the past decade. In fact, Antarctica’s expanding sea ice has been a big argument used by Climate Change deniers.

But now Serreze at the NSIDC is worried that “Antarctica is the sleeping elephant that is beginning to stir.”

This year the Antarctica ice has scored a new record low for the month of November over the period of satellite observations. It is the smallest for early December at 11.22 million square kilometers (4.33 million square miles), beating a record from 1982, as per NSIDC.

In 2016, the Antarctic sea ice reached its annual maximum extent on August 31, much earlier than average, and has been declining rapidly. Scientists worry that Antarctica’s glaciers are likely to slip more quickly into the ocean, thus increasing the pace of sea level rise, if there is less ice floating on the sea to pin them back.

Why this is happening

This is happening because of abnormally high air temperatures, winds from the south, and a warm ocean, says the NSIDC. Air temperatures near the sea were above the 1981 to 2010 average over the entire Arctic Ocean and, locally up to 10 degrees Celsius above average near the North Pole. As a result, the water was too warm for ice to form. In the southern hemisphere air temperatures were 2 to 4 degrees Celsius above average near the sea ice edge during late October and early November, corresponding to the period of rapid sea ice decline.

ocean-temp-earth
Sea surface temperature on October 25, 2016. Ocean surface temperatures were found to be 4 degrees Celsius above the salinity-adjusted freezing point.
air-temp-arctic
Air temperature difference in the Arctic for Nov 2016. Credit: NSIDC courtesy NOAA/ESRL Physical Sciences Division
antarctic-air-temp
Air temperature difference in the Antarctic for Oct 27 to Nov 17, 2016. Credit: NSIDC courtesy NOAA/ESRL Physical Sciences Division

A research by students from the University Centre in Svalbard, Norway, noted an unusually warm ocean surface layer about 4 degrees Celsius above the salinity-adjusted freezing point.

The Arctic Ocean was expected to get warmer for a reason. As the climate gets warmer and Arctic Ocean was to have less sea ice, thus turning the ocean darker. This dark ocean in turn was expected to absorb more energy from sunlight, energy the white ice would have reflected away otherwise. The heat absorbed by the ocean would also prevent sea ice formation.

What makes it a triple whammy is the fact that as the ice caps shrunk, the oldest and thickest ice has either thinned or melted away, leaving the sea ice cap more vulnerable to the warming ocean and atmosphere.

NSIDC’s Sea Ice Index data relies on NASA-developed methods using passive microwave data from the Defense Meteorological Satellite Program (DMSP) F-18 Special Sensor Microwave Imager/Sounder (SSMIS). The basis for the Sea Ice Index is the data set, Near-Real-time DMSP SSM/I-SSMIS Daily Polar Gridded Sea Ice Concentrations, and the NASA-produced Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I Passive Microwave Data. The Sea Ice Index was developed with financial support from NOAA NESDIS and in cooperation with NOAA NGDC.

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