全球變暖帶來的不只是酷熱的夏天，還可能引發暴雨、洪災和供水不足。研究發現，全球溫度每升高1攝氏度，高海拔地區發生特大暴雨的幾率就會增加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.

一項新研究發現，全球變暖正在將山區的強降雪轉變成特大暴雨，從而引發危險的洪災和長期的缺水問題。

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.

根據發表在《自然》雜志上的這項研究，科學家查看了1950年以來的雨雪測量結果以及電腦模擬未來氣候的數據，估算出這樣一個結果：全球溫度每升高1華氏度/1攝氏度，高海拔地區發生特大暴雨的幾率就會增加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.

科學家指出，相比山區的強降雪，強降雨引發的問題多得多，包括洪水、滑坡和侵蝕。因為雨水不像積雪那么容易儲存，積雪融化以后還能在春夏充盈水庫。

"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.

該研究的首席作者、勞倫斯伯克利國家實驗室的水文學家、氣候學家穆罕默德·翁巴迪稱：“這不是未來可能發生的遙遠的問題，而是已經在發生，從過去幾十年的數據就能看到。”

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.

這項研究考察了北半球60年來每年最強降雨的數據后發現，海拔越高，雨下得越大。降雨量增幅最明顯的地方海拔高度約為3000米，其中包括美國西部的大部分地區（翁巴迪表示“降雨增幅非常顯著”）以及阿巴拉契亞山脈的部分地區。另外一個降雨增幅明顯的地區是亞洲的喜馬拉雅山、天山山脈和興都庫什山脈。阿爾卑斯山脈的降雨量也受到了氣候的影響。

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.

翁巴迪稱，地球上大約有四分之一的人口生活在可能遭遇特大暴雨或洪水的山區或山腳附近。

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，洪水還會損害糧食生產。他指出，美國加州農業部估計今年的暴雨將造成8900萬美元（約合人民幣6.45億元）的農作物和牲畜損失。

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.

但是長期來看，供水也是一個問題。通常美國西部地區冬天下大雪時，積雪會在來年春天和夏天慢慢融化填充到水庫中，以供不時之需。

"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.

該研究的合著者、實驗室氣候科學家、水文學家查如樂卡·瓦拉德哈拉詹表示：“降雪將會減少，未來供水也會不足。”

英文來源：美聯社

翻譯&編輯：丹妮