A By the time you read these words, winter should have gone within the Northern Hemisphere (半球). But at its worst, this winter was unusually cold. Here in New York City on January 31, the low temperature dropped to -17°C. In Chicago, it was also -17°C—but that was the high. The low jumped to -29°C. And the wind chill within the Windy City was -44°C or -46°C, relying on which climate station was crying out in pain. As comic Lewis Black said, “That is not weather. That’s an emergency condition.” When the forecast warned us a few days earlier that Arctic air was looming (阴森地逼近), President Trump issued a sincere and helpful tweet, which ended with: “What the hell is going on with Global Waming? Please come back fast, we need you!” And being the most powerful man on Earth, he was successful in his polite request. On February 4 the Chicago temperature reached 11°C. And the following day the Big Apple was in a sunny 19°C. The Arctic is warming at twice the speed as the global average. This heat might help disrupt (打破)the polar vortex, a gradual wind pattern that usually stays focused on circling the North Pole. A shaky jet stream(高速气流)then runs right into a brick wall of that Arctic air, which continues to be fairly cold by human standards, and both wind up lots of miles farther south than they usually belong. And for a few days we in the Deep South—by which I mean Chicago or New York compared with the Arctic—freeze our butts off. But less than a week later, thanks to some warm air coming up from the real South, I was walking outside without a coat on a date when the temperature in Chicago reached 11°C on February 4. Like so much else we are currently living through, this experience is not normal. Or it didn’t used to be, anyway. After all, scientists have been waming—sorry, warning—that warming can have these very results. Climate change deniers may sneer(冷笑), “So when it’s warmer than usual, that’s because of global warming. And when it’s colder, that’s also because of global warming?” Well, yes. And anybody who just can’t accept these kinds of seemingly paradoxical conditions needs to reflect on the expression “freezer burn.” 1. By mentioning Lewis Black’s words in Paragraph 1, the author intends to _______.