Climate change is supposed to unfold slowly, over decades. But that is not true up in the great white north, as those attending

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问题     Climate change is supposed to unfold slowly, over decades. But that is not true up in the great white north, as those attending the AAAS meeting’s session on climate change in the Arctic were reminded. Temperatures there are 2°C higher than their long-term average, and the upper layers of parts of the Arctic Ocean are hotter than they have been for at least 2,000 years. Summer sea ice has been vanishing faster than even the gloomiest researchers thought likely, with some now predicting the first completely ice-free summer as soon as the 2020s.
    The Arctic is not, though, isolated from the rest of the world; rapid changes there could have knock-on effects elsewhere. Whether or not that is happening was a question addressed by Jennifer Francis, an atmospheric scientist at Rutgers University. It is a topical subject. Along with much of the rest of America, Chicago endured a fierce and prolonged cold snap in January, in which temperatures fell to -27°C, the lowest since 1884. Meanwhile, Brits at the conference were fleeing a country that had been soaked by the heaviest winter rains in two and a half centuries, and battered by a seemingly endless succession of Atlantic storms and gales.
    Campaigners in both countries have been quick to blame climate change for the rotten weather. But things are rarely so straightforward in climatology. The best Dr Francis could offer was a theory as to why a warmer Arctic might be expected to lead to wilder weather in mid-latitudes, and some tentative but suggestive evidence that this is already happening.
    Her idea rests on the jet stream, a powerful, persistent, high-altitude "river of air" which flows around the world from west to east, affecting the weather as it goes. The jet stream is driven in part by the temperature difference between cold Arctic air and the warmer air of middle latitudes. Because the Arctic is warming more rapidly than the rest of the planet, that difference is shrinking. This ought to produce a less potent jet stream. And a less potent jet stream is a more unpredictable one.
Pessimistic researchers foretell that ______.

选项 A、climate change will slowly show up in decades
B、ice of the Arctic may melt in summer very soon
C、the Arctic temperature has been the hottest in 2,000 years
D、global temperatures are 2°C higher than long-term average

答案B

解析 根据题干中的“pessimistic researchers”定位到第一段最后一句。其中“pessimistic researchers”对应“gloomiest researchers”;“foretell”对应“predicting”,故答案来自predicting后面的内容。即“the first completely ice-free summer as soon as the 2020s”,该句内容对应B项ice of the Arctic may melt in summer very soon,因此答案为选项B。
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