美国2017年气候反常 三个月来连破高温纪录

It's been so warm in the United States this year, especially in March, that national records weren't just broken, they were deep-fried.

Temperatures in the lower 48 states were 8.6 degrees above normal for March and 6 degrees higher than average for the first three months of the year, according to calculations by the National Oceanic and Atmospheric Administration. That far exceeds the old records.

The magnitude of how unusual the year has been in the US has alarmed some meteorologists who have warned about global warming. One climate scientist said it's the weather equivalent of a baseball player on steroids, with old records obliterated.

"Everybody has this uneasy feeling. This is weird. This is not good," said Jerry Meehl, a climate scientist who specializes in extreme weather at the National Center for Atmospheric Research in Boulder, Colo. "It's a guilty pleasure. You're out enjoying this nice March weather, but you know it's not a good thing."

It's not just March.

"It's been ongoing for several months," said Jake Crouch, a climate scientist at NOAA's National Climatic Data Center in Ashville, N.C.

Meteorologists say an unusual confluence of several weather patterns, including La Nina, was the direct cause of the warm start to 2017. While individual events can't be blamed on global warming, Crouch said this is like the extremes that are supposed to get more frequent because of manmade climate change from the burning of fossil fuels such as coal and oil.

Normally, March averages 42.5 degrees across the country. This year, the average was 51.1, which is closer to the average for April. Only one other time — in January 2006 — was the country as a whole that much hotter than normal for an entire month.

In March, at least 7,775 weather stations across the nation broke daily high temperature records and another 7,517 broke records for night-time heat. Combined, that's more high temperature records broken in one month than ever before, Crouch said.

"When you look at what's happened in March this year, it's beyond unbelievable," said University of Victoria climate scientist Andrew Weaver.

美国今年天气十分暖和，特别是三月以来，温度居高不下。这不仅是破纪录的高温，而且热度灼人。

据美国国家海洋和大气管理局的测算，美国南部48个州今年三月的温度比正常水平高了8.6华氏度，前三个月的平均温度比平均水平高出了6华氏度。这远远超出了历史记录水平。

美国今年是如此反常，让一些气候学家感到担忧，此前他们已经对全球变暖提出过警告。一位气候学家称，这就像服用了类固醇兴奋剂的棒球运动员刷新历史记录一样，事有异常。

专门研究极端天气的气候学家杰里•米尔说：“大家都有这种不安的感觉。这太诡异了，情况不妙。这是一种让人无法开怀享受的愉悦。你在户外享受着这美好的三月天气，但是你知道，这不是件好事。”米尔在科罗拉多州博尔德的国家气候研究中心工作。

并不只有三月份如此。

气候学家杰克•克劳趣说：“这种高温已经持续了几个月。”克劳趣在国家海洋和大气管理局位于北卡罗来纳州阿什维尔的国家气候数据中心工作。

气候学家称，包括拉尼娜现象在内的几种气候类型的异常交汇是导致2017年初以来温暖天气的直接原因。尽管不能将个别事件归因于全球变暖，但克劳趣称，就像燃烧煤油等化石燃料、人为导致的气候变化引发的极端天气一样，这种极端天气只会愈加频繁。

正常情况下，美国三月的平均气温为华氏42.5度。今年美国三月的平均气温为51.1度，这更接近往年四月的平均温度。这种整个月气温大大高于正常水平的情况在美国只出现过一次——在2006年一月。

三月期间，美国至少7775个气象站测得的日最高气温打破记录，还有7517个气象站测出的夜间气温破了纪录。克劳趣说，二者加在一起，这一个月打破的高温记录比往年都要多。

维多利亚大学的气候学家安德鲁•韦佛说：“如果你好好看看今年三月的天气情况，你会觉得太难以置信了。”