每日英語跟讀 Ep.952: How low did it go? Scientists calculate Earth’s Ice Age temperatures 科學家算出冰河期地球氣溫

Guided by ocean plankton fossils and climate models, scientists have calculated just how cold it got on Earth during the depths of the last ice age, when immense ice sheets covered large parts of North America, South America, Europe and Asia.

在海洋浮游生物化石和氣候模型的引導之下，科學家近日計算出地球在上一次冰河時期最酷寒的期間，氣溫到底有多冷。浩瀚無際的冰原當時覆蓋著北美洲、南美洲、歐洲和亞洲的大多數區域。

The average global temperature during the period known as the Last Glacial Maximum from roughly 23,000 to 19,000 years ago was about 7.8°C, 7°C colder than last year, the researchers said Aug. 26. Certain regions were much cooler than the global average, they found. The polar regions cooled far more than the tropics, with the Arctic region 14°C colder than the global average.

研究人員於八月二十六日指出，大約在二萬三千年到一萬九千年前的「末次冰盛期」，地球平均溫度約為攝氏七‧八度，比去年均溫低了七度左右。他們發現，特定地區的溫度比全球平均還要冷上許多。極圈地區降溫的程度遠大於熱帶地區，像是北極圈就比全球平均溫度還要低十四度。

The researchers made their calculations with the aid of chemical measurements on tiny fossils of zooplankton and the preserved structures of fats from other types of plankton that change in response to water temperature — what they called a “temperature proxy.” This information was then plugged into climate model simulations to calculate average global temperatures.

研究人員藉由化學量測的輔助完成計算。他們測量了微小的浮游動物化石，以及其他種類浮游生物被保存下來的脂肪結構，這類隨著水溫改變而發生的變化被稱為「溫度替代指標」。接下來，研究人員再將這些資訊帶入氣候模式模擬，來算出全球平均溫度。

“Past climates are the only information we have about what really happens when the Earth cools or warms to a large degree. So by studying them, we can better construe what to expect in the future,” said University of Arizona paleoclimatologist Jessica Tierney, lead author of the research published in the journal Nature.

該研究的主要作者、美國亞利桑那大學的古氣候學家潔西卡‧提爾尼表示：「過去的氣候是我們擁有的唯一資訊，藉此得知地球在大幅度冷卻或暖化時實際發生過什麼。所以，藉由研究過去氣候，我們可以進一步推斷未來可預期的情況。」這份研究近日發表於《自然》科學期刊。

During the ice age, which lasted from about 115,000 to 11,000 years ago, large mammals well adapted to a cold climate, such as the mammoths, mastodons, woolly rhinos and saber-toothed cats, roamed the landscape.

冰河時期從十一萬五千年前持續到一萬一千年前。這段時期，對寒冷氣候適應良好的大型哺乳類動物，例如猛瑪象、乳齒象、披毛犀，以及劍齒虎，漫步於冰封的地貌中。

Humans entered North America for the first time during the ice age, crossing a land bridge that once connected Siberia to Alaska with sea levels much lower than they are today. Human hunting is believed to have contributed to mass extinctions globally of many species at the end of the ice age.

人類在冰河時期首度進入北美洲。由於當時的海平面比現在低很多，人類得以跨越曾經把西伯利亞和阿拉斯加連結起來的陸橋。人類的狩獵活動被認為是許多物種在冰河時期結尾發生全球性大滅絕的主因。

“What is interesting is that Alaska was not entirely covered with ice,” Tierney said. “There was an ice-free corridor that allowed humans to travel across the Bering Strait, into Alaska. Central Alaska was actually not that much colder than today, so for ice age humans it might have been a relatively nice place to settle.”

「有趣的是，阿拉斯加當時並非全面被冰覆蓋。」提爾尼指出：「當時那邊有一條無冰的『廊道』，讓人類得以穿過白令海峽，抵達阿拉斯加。另外，當時的阿拉斯加中部其實沒有比今日冷很多，所以對冰河時期的人類而言，當地也許曾經是一個相對舒適的定居地。」

Source article: https://www.taipeitimes.com/News/lang/archives/2020/09/06/2003742869