全國高溫濕熱持續不斷，而這僅僅是個開始……
極端天氣
近日，我國持續高溫濕熱天氣，多地遭遇了暴雨襲擊，引發各方的密切關注。而美國、加拿大、英國等國家也遭受了嚴重高溫濕熱的影響。在加拿大，超過七十人死於異常悶熱的天氣；在美國賓夕法尼亞州，公路因高溫融化。
哥大的一項研究表明，長時間的高溫環境會極大損害人的認知能力。
近年來，全球高溫天氣愈發頻繁，高溫預警持續不斷。去年底，一項哥倫比亞大學拉蒙特-多爾蒂地球觀測研究所的研究表示，這些均是氣候變化的嚴正警告。科研人員認為，基於目前氣候變化的趨勢，至本世紀末，高溫天氣將超出人類的承受範圍。
The frequency of lethally hot weather is increasing, as is the duration of high-risk heat. These facts are grim reminders of the findings of a report, published late last year, by climatologists from Columbia"s Lamont-Doherty Earth Observatory. The researchers reported that, considering the present climate change trajectory, heat stress could exceed human endurance by the end of the century.
該項研究顯示，在未來的幾十年內，極端濕熱天氣將造成更為劇烈的影響。屆時，濕熱天氣會讓人們無法正常工作，甚至在某些極端情況下，造成生命威脅。特別是在那些以戶外勞動為主、空調尚未普及的地區，人類健康和經濟發展將遭受重創。目前氣候已經十分潮濕的地區則更容易受到影響，包括美國東南部、亞馬遜河流域、非洲西部和中部、中東南部和阿拉伯半島、印度北部以及中國東部。
A new global study projects that in coming decades the effects of high humidity in many areas will dramatically increase. At times, they may surpass humans" ability to work or, in some cases, even survive. Health and economies would suffer, especially in regions where people workoutside and have little access to air conditioning. Potentially affected regions include large swaths of the already muggy southeastern United States, the Amazon, western and central Africa, southern areas of the Mideast and Arabian peninsula, northern India and eastern China.
這份研究報告以「濕球溫度」為測量標準，即表示熱度和適度的指數。實驗證明，當濕球溫度達到32℃時，人類面臨戶外活動的最大臨界值。超過32℃，人們將無法在戶外進行正常活動。儘管這類天氣情況在今天仍屬罕見，但該項目的第一作者Ethan Coffel表示，至本世紀末，高溫濕熱天氣的發生頻率將大幅上升。
The report discusses "wetbulb" measurements, an index of the combination of heat and humidity. Lab experiments have shown wet-bulb readings of 32 degrees Celsius are the thres hold beyond which many people would have trouble carrying out normal activities outside. Although it is not frequently occurred nowadays, 「the conditions we』re talking about are projected to occur close to the end of the century,」 said lead author Ethan Coffel.
Map: Ethan Coffel
儘管對高溫濕熱天氣的預測集中發生在未來幾十年，但目前的天氣狀況已經給人們帶來了很多不可小覷的健康問題。
Although the report"s most grim projections are set in the future, the increasing periods of high heat and humidity are already having dramatic health impacts.
通常情況下，人們認為全球變暖會影響降水量，從而讓乾燥的地區更為乾燥。但隨著全球氣溫的升高，大氣中聚集了更多的水蒸氣。這就意味著沿海或長時間處於濕熱天氣的地區會變得越來越潮濕。濕熱往往要比乾熱更讓人難受，這是因為人類和其他哺乳動物都是通過汗液蒸發散熱來降溫。這種降溫方式在沙漠中很有效。但當空氣中含有大量水汽，汗液從體表蒸發的速度減慢，最終因為空氣中濕度過高，人類自身的降溫機制將受到阻礙。這就導致人類體內溫度的變化較小，一旦氣溫過高，在沒有空調的情況下，人體機能會開始崩潰，會導致嗜睡、噁心嘔吐，甚至可能致死。
Warming climate is projected to make many now-dry areas dryer, in part by changing precipitation patterns. But by the same token, as global temperatures rise, the atmosphere can hold more water vapor. That means chronically humid areas located along coasts or otherwise hooked into humid-weather patterns may only get more so. And, as many people know, muggy heat is more oppressive than the 「dry」 kind. That is because humans and other mammals cool their bodies by sweating; sweat evaporates off the skin into the air, taking the excess heat with it. It works nicely in the desert. But whenthe air is already crowded with moisture—think muggiest days of summer in the city–evaporation off the skin slows down, and eventually becomes impossible. When this cooling process halts, one"s core body temperature rises beyond the narrow tolerable range. Absent air conditioning, organs strain and then start to fail. The results are lethargy, sickness and, in the worst conditions, death.
該項研究的聯合作者、拉蒙特-多爾蒂地球觀測研究所氣候學家萊德利·霍爾頓表示：「極端濕熱天氣可能造成的健康危害一直被人們忽視，隨著氣溫和濕度的不斷上升，在更多地區，戶外勞動將會威脅人類健康，同時空調也會變得必不可缺。」
「The health dangers associated with extreme heat and humidity remain grossly under appreciated,」 saidcoauthor Radley Horton, a climate scientist at Lamont-Doherty. 「As temperature and humidity rise in the future, more and more regions will experience conditions in which outdoor labor is dangerous, and air conditioning is essential.」
此前，僅有少數研究在關注濕度變化。拉蒙特-多爾蒂地球觀測研究所在已有的相關研究的基礎上，將其擴展至全球氣候模型，並也將未來人口增長納入了考量範圍。
Only a handful of previous studies have looked at the humidity issue in relation to climate change. The new study builds on the earlier research, extending the projections globally using a variety of climate models and taking into account future population growth.
編譯：紅旗
責編：翩躚
