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& # 39; Precipitation & # 39; fall in the sea of ​​Antarctica since 2014 revealed | World news



The high prevalence of sea ice around Antarctica has suffered a "precipitation" decline since 2014, satellite data shows and fell faster than seen in the Arctic.

The jump in the average annual volume means that Antarctica lost so much sea ice for four years as an Arctic lost in 34 years. The cause of the sharp Antarctic losses is still unknown, and only time will tell if the ice regains or continues to fall.

But scientists said that ice could disappear much faster than previously thought. Unlike melting ice sheets on land, sea melting does not raise sea level. But losing the bright white sea ice means that the sun's heat is instead absorbed by dark sea water, leading to a vicious circle of warming.

Antarctica's average annual volume is 1979-2018

Sea ice spreads over vast areas and has major implications for the global climate system, with losses in the Arctic strongly associated with extreme weather at lower latitudes, such as. Heat waves in Europe.

The loss of ice in the Arctic clearly tracks the increase in global air temperatures as a result of man-made global warming, but the two poles are very different. The Arctic is a sea surrounded by continents and exposed to the warming of the air, while Antarctica is a frosty continent surrounded by oceans and is protected from the warming of the air by a circle of strong winds.

Antarctic sea ice was slowly rising over 40 years of measurements and reached a record high in 2014. But since then, the ice boundary has been nosedived and reached a record low in 2017.

"There has been a big drop," Claire Parkinson at Nasa's Goddard Space Flight Center in the United States. In her study, published in the journal Proceedings of the National Academy of Sciences, she called the decline and a dramatic turn.

"We don't know if that will continue," she said. "But it raises the question of why [has it happened] and we will see some great acceleration in the fall of the Arctic? Only the continuing record tells us."

"The Arctic has become a poster child for global warming," Parkinson said, but it The recent sea ice decline in Antarctica has been much worse. She has been tracking antarctic sea ice for more than 40 years. "All of us scientists finally thought that global warming will catch up in Antarctica," she said.

Kaitlin Naughten, a marine scientist at the British Antarctic Study, said: "Westerly winds that surround the continent mean that the Sea of ​​Antarctica does not respond directly to global warming around the world."

"Climate change affects the winds, but is also the ozone hole and short-term cycles like El Niño. The sea ice is also affected by melt water flowing from the arctic sheet in the Antarctic, "she said. "Until 2014, the overall impact of all of these factors was that the Antarctic sea ice was to be expanded. However, in 2014, something fluctuated and the seismic has since fallen dramatically. Now, scientists are trying to figure out exactly why this happened."

Prof Andrew Shepherd of Leeds University in the UK said: "The rapid fall has surprised us and alters the picture altogether. Now the seismic returns in both hemispheres, and it poses a challenge because it can cause further warming." He said it too would be important to find out if the ice thickness has changed as well as its extent.

The new research was collected microwave satellite data from 1979 to 2018, providing excellent measurements of sea ice, as the various signals from the ice and sea are very different, and microwaves can be detected day or night and usually through clouds.

In the winter, Havis expands and retreats in the summer each year, so Parkinson spent annual averages to assess long-term trends. The biggest annual decline fell in 2016, when an El Niño increased man-made heating to result in record high temperatures.

She said that the decline after 2014 was three times faster than the fastest melting ever recorded in the Arctic. Sea ice stretch had a slight increase in 2018, but by 2019 so far there had been a further reduction, she said.

Parkinson said the dramatic leap was a strong evidence that scientists could use to narrow down the causes of change. "As a Nasa researcher, my main responsibility is to get satellite data out, and I hope others will take this 40-year record and try to figure out how these dramatic declines have been explained since 2014," she said.


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