Eric Chaney
Published: October 21,2015
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New images from NASA show a dramatic change in the maximum extent of Antarctic sea ice observed in 2014 and 2015.
A
new map released by NASA shows a dramatic change in the level of sea
ice around Antarctica, but scientists at the agency’s Goddard Space
Flight Center say the change is simply a “return to normalcy” after a
streak of record-breaking high ice years.
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The
maximum extent of Antarctic sea ice in 2015 was considerably lower this
year than in the past three years, each of which have been record
breaking.
(NASA)
Each of the
previous three years broke a new record for the largest maximum extent
of sea ice around the southern pole in the satellite era. In 2014,
Antarctic sea ice reached is maximum extent on September 20, covering
7.78 million square miles. In 2015, the maximum extent covered just 7.27
million square miles, 16th on the list and the lowest since 2008. According
to the National Snow and Ice Data Center, this year’s maximum extent
was slightly above average for all measurements taken between 1981 and
2010 average and occurred relatively late in the year compared to past
years.
NASA reports indicate that the growth of Antarctic sea ice
was erratic this year. Sea ice was at much higher than normal levels
throughout much of the first half of 2015 until, in mid-July, it
flattened out and even went below normal levels in mid-August. The sea
ice cover recovered partially in September, but not enough to match
recent years.
(MORE: Antarctic Sea Ice Reaches Record High in 2014)
Data
for the new maps were acquired by the Advanced Microwave Scanning
Radiometer 2 sensor on Japan’s Global Change Observation Mission
1st–Water (GCOM-W1) satellite. In 2015, sea ice coverage was greater
than average around the Antarctic Peninsula, the Weddell Sea, and the
Wilkes Land coast, according to an analysis by the National Snow &
Ice Data Center. The Ross Sea and the Indian Ocean-facing coast had
below average sea ice.
Scientists still don’t know all of the factors that play into the development of Antarctic sea ice.
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The maximum extent of Antarctic sea ice in 2015 didn't quite make it to the record levels experienced in 2013 and 2014.
(NASA)
“Part
of it is just the geography and geometry,” Goddard research scientist
Walt Meier said in 2014. “With no northern barrier around the whole
perimeter of the ice, the ice can easily expand if conditions are
favorable.”Many other factors are thought to play into ice
development as well, including Antarctic wind patterns, snowfall, and
even El NiƱo.
“There hasn’t been one explanation yet that I’d say
has become a consensus, where people say, ‘We’ve nailed it, this is why
it’s happening,’” Claire Parkinson, a senior scientist at Goddard said
in 2014. “Our models are improving, but they’re far from perfect. One by
one, scientists are figuring out that particular variables are more
important than we thought years ago, and one by one those variables are
getting incorporated into the models.”
MORE: Glacial Melt in Antarctica
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