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  3. In 2020, ice cover in the Arctic Ocean hit an all-time low for this time of year on July 15, according to the National Snow and

In 2020, ice cover in the Arctic Ocean hit an all-time low for this time of year on July 15, according to the National Snow and

admin2021-09-25  4
问题     In 2020, ice cover in the Arctic Ocean hit an all-time low for this time of year on July 15, according to the National Snow and Ice Data Center. Its data also suggests that sea ice was disappearing at a rate of more than 56,400 square miles a day earlier this month compared with the typical rate of 33,000 square miles. Satellites have never seen so little ice in July. The Siberian coast has been hit hardest. The Northeast Passage, a shipping route along the Russian shoreline, was ice-free two weeks ago.
    Sea ice typically continues to melt in the Arctic Ocean through the summer, hitting its lowest point in September, before it begins to refreeze. Given the remarkable season so far, some experts have speculated that it could reach an all-time low in September. That record was last broken in 2012, the most extreme year in history for Arctic ice cover. Sea ice extent that year was 18% lower than the previous all-time low in 2007 and nearly 50% lower than the average between 1979 and 2000.
    Those records might be toppled this year. Unusually hot and sunny conditions have primed the region for a big melt. In June, a persistent high-pressure system—a kind of swirling atmospheric current often associated with clear, sunny skies—set up camp over the Siberian Arctic. Temperatures soared, culminating in a shocking 100-degree Fahrenheit day in the town of Verkhoyansk, Russia. It was the first time that ever happened.
    Then, this week, scientists flagged another threat to the ice. A swirling cyclone has brewed over the western Arctic Ocean for the last few days, sparking concerns that the storm could break up the sea ice and cause it to melt even faster. Faster melting tends to become a self-reinforcing system in the Arctic. As the ice disappears, patches of open ocean absorb more sunlight and heat, further warming the water and melting more ice. Arctic cyclones aren’t uncommon—they happen all the time. But this storm was unusually strong for July and raised warnings about the impact of a similar cyclone in 2012 that some scientists say helped cause record melting that year.
    But it’s likely too soon to tell how this storm may affect dwindling sea ice. Zachary Labe, a climate scientist at Colorado State University, noted that this year’s events aren’t a direct parallel to what happened in 2012. He suggested that an unusually intense cyclone damaged the ice in 2012 and contributed to the astonishing record low extent in September. But that cyclone was abnormally persistent, lasting about two weeks, while this week’s cyclone is fizzling out after just a few days.
    With the ocean warming up so much along Siberia, it would not a surprise if the sea ice takes longer to re-form in the fall, because there’s been so much heat building up. And this, in turn, could set the region up for even more declines in ice storage next summer.
What prompted the sea ice extent in the Arctic Ocean to hit an all-time low according to Paragraph 3?
选项 A、Extreme weather conditions.
B、Human camping activities.
C、Wildfire in Russian Forests.
D、Global warming.
答案A
解析 细节题。第三段主要提到了造成海冰融化的因素，不寻常的炎热、阳光充足的条件、持续的高压系统等都属于天气因素，由此可知，2020年这次海冰融化主要是由极端恶劣的气象条件引发的，因此，选[A]。
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