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Arctic Sea Ice May Be Shrinking Faster Than Thought, says Study

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Canadian Arctic
An iceberg floats past Bylot Island in the Canadian Arctic Archipelago. VOA
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Arctic sea ice may be thinning faster than predicted because salty snow on the surface of the ice skews the accuracy of satellite measurements, a new a study from the University of Calgary said on Tuesday.

The report from the Canadian university’s Cryosphere Climate Research Group published in the academic journal Geophysical Research Letters found satellite estimates for the thickness of seasonal Arctic sea ice have been overestimated by up to 25 percent.

That means the Arctic Ocean could be ice-free much sooner than some scientific predictions, which forecast Arctic sea ice will first disappear completely during summer months between 2040 and 2050, according to lead author Vishnu Nandan.

Ice-free summers in the Arctic Ocean would impact global weather patterns by increasing the magnitude and frequency of major storms and alter the Arctic marine ecosystem, making it harder for animals like polar bears to hunt.

There is a wide range of projections as to when Arctic sea ice will start disappearing in the summertime as a result of warming global temperatures, and the University of Calgary study calls into question satellite measurements provided so far.

“The problem is, microwave measurements from satellites don’t penetrate the salty snow very well, so the satellite is not measuring the proper sea ice freeboard and the satellite readings overestimate the thickness of the ice,” Nandan said.

The Arctic sea ice freeboard refers to ice that can be seen above sea level and co-researcher John Yackel said, “Our results suggest that snow salinity should be considered in all future estimates on the Arctic seasonal ice freeboard made from satellites.”

Reporting by Nia Williams; editing by Diane Craft.(VOA)

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Arctic and Antarctic Sea Ice hit its lowest extent ever recorded by Satellites: Scientists

The ice floating on top of the Arctic Ocean and surrounding seas shrinks in a seasonal cycle from mid-March until mid-September

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Ice Loss in Antarctic Sea, VOA

Washington, March 23, 2017: While Arctic Sea ice reached this year a record low wintertime maximum extent, sea ice around Antarctica also hit its lowest extent ever recorded by satellites at the end of summer in the Southern Hemisphere, scientists have said.

In February this year, the combined Arctic and Antarctic sea ice extent was at its lowest point since satellites began to continuously measure sea ice in 1979, said scientists at NASA and the NASA-supported National Snow and Ice Data Center (NSIDC) in Boulder, Colorado.

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Total polar sea ice covered 16.21 million square km, which is two million square km less than the average global minimum extent for 1981-2010 — the equivalent of having lost a chunk of sea ice larger than Mexico, the study said.

“It is tempting to say that the record low we are seeing this year is global warming finally catching up with Antarctica,” Walt Meier, a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in a NASA release on Wednesday.

“However, this might just be an extreme case of pushing the envelope of year-to-year variability. We’ll need to have several more years of data to be able to say there has been a significant change in the trend,” Meier added.

The ice floating on top of the Arctic Ocean and surrounding seas shrinks in a seasonal cycle from mid-March until mid-September.

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As the Arctic temperatures drop in the autumn and winter, the ice cover grows again until it reaches its yearly maximum extent, typically in March.

The ring of sea ice around the Antarctic continent behaves in a similar manner, with the calendar flipped –it usually reaches its maximum in September and its minimum in February.

This winter, a combination of warmer-than-average temperatures, winds unfavourable to ice expansion, and a series of storms halted sea ice growth in the Arctic, the scientists said.

This year’s maximum extent, reached on March 7 at 14.42 million square kilometres, is 97,00 square kilometres below the previous record low, which occurred in 2015, and 1.22 million square kilometres smaller than the average maximum extent for 1981-2010, according to the scientists. (IANS)