Sea Ice around Antarctica Shows Sharp Decrease


04 July, 2019

蜗蜗牛小游戏网 www.liandama.cn Scientists say the amount of sea ice around Antarctica has decreased from a record high to a record low in only a few years.

Sea ice is ice covering the ocean rather than land.

Ice floating in the waters around the Antarctic continent started increasing in 1979, about the time satellite observations first started.

This January 2017 photo provided by Ted Scambos shows sea ice on the ocean surrounding Antarctica during an expedition to the Ross Sea.
This January 2017 photo provided by Ted Scambos shows sea ice on the ocean surrounding Antarctica during an expedition to the Ross Sea.

The amount of Antarctic sea ice reached a record high in 2014. But a study of data gathered by satellites from the United States space agency NASA showed something different three years later. The data suggested that the yearly average amount of Antarctic sea ice reached its lowest level.

Scientists released the findings on July 1 in a study published in the Proceedings of the National Academy of Sciences.

National Snow and Ice Data Center director Mark Serreze said that, in recent years, "things have been crazy." He told The Associated Press the quickly decreasing ice levels are a "white-knuckle ride."

Serreze and other experts said they do not know what has caused the loss of ice. It could be a natural change, or a result of rising world temperatures caused by human activity.

"But the fact that a change this big can happen in such a short time should be viewed as an indication that the Earth has the potential for significant and rapid change," said University of Colorado ice scientist Waleed Abdalati.

In the polar areas, sea ice levels increase during the winter and shrink in the summer. Around Antarctica, sea ice covered an average area of 12.8 million square kilometers in 2014. But the study shows that by 2017, only 10.7 million square kilometers of sea was covered by ice.

The difference represents an area bigger than the size of Mexico.

Claire Parkinson is the NASA climate scientist who wrote the report. She says losing that much sea ice in just three years "is pretty incredible" and faster than anything scientists have seen before.

Antarctic sea ice increased slightly in 2018. Although sea ice is expanding during the winter in Antarctica, levels in May and June of this year were the lowest on record, the ice data center reported.

Antarctica's temperatures are generally lower than those near the North Pole. In the north, the Arctic is a floating collection of ice on an ocean surrounded by land. Antarctica, in the south, is just the opposite, with land surrounded by an ocean. That causes the ice to develop much farther out, Parkinson said.

When Antarctic sea ice was expanding, scientists pointed to changes in wind and air pressure or the movements of the ocean. They also considered natural ongoing changes in the climate.

Now, some of those explanations may need to be reconsidered, making what happens next a mystery, Parkinson said.

I'm Pete Musto.

Seth Borenstein reported this story for the Associated Press. Pete Musto adapted it for VOA Learning English. Mario Ritter Jr. was the editor.

We want to hear from you. What effect do you think decreasing sea ice around Antarctica will have? Write to us in the Comments Section or on www.liandama.cn.

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Words in This Story

crazy adj. very unusual

white-knuckle riden. an experience marked by, causing, or experiencing intense worry or nervousness

indicationn. something, such as a sign or signal, that points out or shows something

potentialn. a chance or possibility that something will happen or exist in the future

significantadj. large enough to be noticed or have an effect

rapid adj. happening quickly

polaradj. of or relating to the North or South Pole or the region around it

incredibleadj. difficult or impossible to believe

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