全球变暖或引发更多特大暴雨和洪灾

全球变暖带来的不只是酷热的夏天，还可能引发暴雨、洪灾和供水不足。研究发现，全球温度每升高1摄氏度，高海拔地区发生特大暴雨的几率就会增加15%。

A warming world is transforming some major snowfalls over mountains into extreme rain, worsening both dangerous flooding as well as long-term water shortages, a new study has found.

一项新研究发现，全球变暖正在将山区的强降雪转变成特大暴雨，从而引发危险的洪灾和长期的缺水问题。

Using rain and snow measurements since 1950 and computer simulations for future climate, scientists calculated that for every degree Fahrenheit the world warms, extreme rainfall at higher elevation increases by 8.3% (15% for every degree Celsius), according to a study in journal Nature.

根据发表在《自然》杂志上的这项研究，科学家查看了1950年以来的雨雪测量结果以及电脑模拟未来气候的数据，估算出这样一个结果：全球温度每升高1华氏度/1摄氏度，高海拔地区发生特大暴雨的几率就会增加8.3%/15%。

Heavy rain in mountains causes a lot more problems than big snow, including flooding, landslides and erosion, scientists said. And the rain is not conveniently stored away like snowpack that can recharge reservoirs in spring and summer.

科学家指出，相比山区的强降雪，强降雨引发的问题多得多，包括洪水、滑坡和侵蚀。因为雨水不像积雪那么容易储存，积雪融化以后还能在春夏充盈水库。

"It is not just a far-off problem that is projected to occur in the future, but the data is actually telling us that it’s already happening and we see that in the data over the past few decades,” said lead author Mohammed Ombadi, a Lawrence Berkeley National Laboratory hydrologist and climate scientist.

该研究的首席作者、劳伦斯伯克利国家实验室的水文学家、气候学家穆罕默德·翁巴迪称：“这不是未来可能发生的遥远的问题，而是已经在发生，从过去几十年的数据就能看到。”

The study looked at only the heaviest rains each year over six decades in the northern hemisphere, finding that as altitude rose, so did the turbocharging of rain. The biggest increase in rains were noticed at about 10,000ft (3,000 meters). That includes much of the American west, where Ombadi said “it’s very pronounced”, as well as parts of the Appalachian Mountains. Another big hotspot in Asia is the Himalayas, Tian Shan and Hindu Kush mountains, with the Alps also affected.

这项研究考察了北半球60年来每年最强降雨的数据后发现，海拔越高，雨下得越大。降雨量增幅最明显的地方海拔高度约为3000米，其中包括美国西部的大部分地区（翁巴迪表示“降雨增幅非常显著”）以及阿巴拉契亚山脉的部分地区。另外一个降雨增幅明显的地区是亚洲的喜马拉雅山、天山山脉和兴都库什山脉。阿尔卑斯山脉的降雨量也受到了气候的影响。

About one in four people on Earth live in an area close enough to the mountains or downhill that extreme rain and flooding would hit them, Ombadi said.

翁巴迪称，地球上大约有四分之一的人口生活在可能遭遇特大暴雨或洪水的山区或山脚附近。

The flooding also can hurt food production, Ombadi said. He pointed to California department of agriculture estimates of $89m in crop and livestock losses from this year’s torrential rains.

翁巴迪表示，洪水还会损害粮食生产。他指出，美国加州农业部估计今年的暴雨将造成8900万美元（约合人民币6.45亿元）的农作物和牲畜损失。

But in the long term, another problem is water supply. When the American west gets heavy snowfall in the winter, that snow melts slowly in spring and summer, filling reservoirs where it can be useful when it is needed later.

但是长期来看，供水也是一个问题。通常美国西部地区冬天下大雪时，积雪会在来年春天和夏天慢慢融化填充到水库中，以供不时之需。

"It’s going to decrease your snow, your water supply in the future,” said study co-author Charuleka Varadharajan, a lab climate scientist and hydrologist.

该研究的合著者、实验室气候科学家、水文学家查如乐卡·瓦拉德哈拉詹表示：“降雪将会减少，未来供水也会不足。”