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【雙語學習】140年來最熱夏天!人類身體已達極限?

無論你是身處重慶、武漢這樣的著名“火爐”,還是生活在北京、哈爾濱,是個土生土長的東北人,今年夏天都沒能逃過那個共同的關鍵詞——高溫!各地高溫持續不下,33度已經算是相當适宜,如此炎熱的暑假,大家都是如何度過的呢?

 

近日,一位氣候科學家表示,極端高溫天氣正将人體對溫度的忍耐度推向極限,這意味着部分地區在不久的将來很有可能不再适宜人類居住。

本周,破紀錄的高溫席卷歐洲,一些國家的氣溫超過40攝氏度。然而,在南亞和波斯灣等地,人們需要忍受的高溫竟然已達54攝氏度。2019年7月25日,法國巴黎也實現了一次“壯舉”,當地氣溫超過40攝氏度。如果擁有空調還算是幸福的,對于像德國這樣大多數地方都沒有空調的國家來說,百貨商場是人們最愛的福地。

 

拉夫堡大學氣候科學家湯姆·馬修斯博士在The Conversation網站上說,盡管人體的熱效率很高,目前還能承受,但這些區域可能很快就不宜居住了。當氣溫超過35攝氏度時,人體依靠流汗來将核心溫度保持在安全水平。然而,當反映水分蒸發能力的“濕球溫度”達到35攝氏度時,該機能就不再起作用了。(濕球溫度,通過在相關的傳感器或溫度計上包裹濕布來測量。人體通過汗水蒸發來保持内部溫度平衡,當環境濕球溫度高到某個值時,人體就不能通過出汗來維持體溫。)

馬修斯博士表示:“濕球溫度包括溫度計的水分蒸發冷卻效果,因此通常比天氣預報中的正常溫度低得多”,“一旦濕球溫度超過一定值,空氣中就充滿了水蒸氣,汗水就不再蒸發了。”這意味着人體不能自我降溫,這種情況持續幾個小時就能危及生命。他還解釋道:“如果沒有散熱的方法,無論我們喝多少水,在陰涼地呆了多久,人體的核心溫度照樣會上升。”

 

【新聞來源】CHINA DAILY

【原文】

Extreme global temperatures are pushing the human body “close to thermal limits”, according to a climate scientist.

Record-breaking heat has swept through Europe this week with temperatures topping 40C in a number of countries. However, in places such as South Asia and the Persian Gulf, people are already enduring temperatures reaching up to 54C.

Despite all the body's thermal efficiencies, these areas could soon be uninhabitable, according to Loughborough University climate scientist Dr Tom Matthews in The Conversation.

When air temperature exceeds 35C, the body relies on sweating to keep core temperatures at a safe level. However, when the “wet bulb” temperature – which reflects the ability of moisture to evaporate – reaches 35C, this system no longer works.

“The wet bulb temperature includes the cooling effect of water evaporating from the thermometer, and so is normally much lower than the normal (“dry bulb”) temperature reported in weather forecasts,” Dr Matthews wrote.“Once this wet bulb temperature threshold is crossed, the air is so full of water vapor that sweat no longer evaporates,” he said. This means the human body cannot cool itself enough to survive more than a few hours.

“Without the means to dissipate heat, our core temperature rises, irrespective of how much water we drink, how much shade we seek, or how much rest we take,” he explained.

 

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