最后一个冰期的气温到底有多低？ zt

华盛顿（路透社）-在海洋浮游生物化石和气候模型的指导下，科学家们计算出在上一个冰河世纪的深度期间，地球上的冰冷程度，当时冰盖覆盖了北美，南美，欧洲和亚洲的大部分地区。

研究人员在周三表示，在大约23,000至19,000年前的最后一次冰河最高时期，全球平均温度约为46华氏度（7.8摄氏度），比2019年低13华氏度（7摄氏度）。

他们发现，某些地区比全球平均温度低很多。极地地区的冷却远远超过热带地区，北极地区的华氏温度比全球平均水平低25华氏度（14摄氏度）。

研究人员借助化学测量对浮游动物的微小化石和其他类型的浮游生物中保存的脂肪结构进行了计算，这些浮游生物的脂肪会随着水温的变化而变化-他们称之为“温度代理”。

然后将此信息插入气候模型模拟中，以计算全球平均温度。

亚利桑那大学古气候学家杰西卡·蒂尔尼（Jessica Tierney）表示：“过去的气候是我们掌握的有关地球在很大程度上变冷或变暖时真正发生的情况的唯一信息。因此，通过研究它们，我们可以更好地约束未来的期望。”该研究的作者发表在《自然》杂志上。

在大约115,000至11,000年前的冰河时期，大型哺乳动物非常适应寒冷的气候，例如猛ma象，乳齿蜥蜴，羊毛犀牛和剑齿猫在周围漫游。

人类在冰河时期首次进入北美，穿过一座陆桥，该桥曾经将西伯利亚与阿拉斯加连接起来，海平面比今天低得多。

人们认为，在冰河时代末期，人类狩猎已导致全球许多物种的大规模灭绝。

蒂尔尼说：“有趣的是，阿拉斯加并未完全被冰覆盖。” “有一条无冰的走廊，使人类能够穿越白令海峡进入阿拉斯加。阿拉斯加中部实际上并不比今天冷得多，因此对于冰河世纪的人类来说，这可能是一个相对不错的住所。”

 

WASHINGTON (Reuters) - 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.

The average global temperature during the period known as the Last Glacial Maximum from roughly 23,000 to 19,000 years ago was about 46 degrees Fahrenheit (7.8 degrees Celsius), some 13 degrees Fahrenheit (7 Celsius) colder than 2019, the researchers said on Wednesday.

Certain regions were much cooler than the global average, they found. The polar regions cooled far more than the tropics, with the Arctic region 25 degrees Fahrenheit (14 degree Celsius) colder than the global average.

 

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.

"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 constrain what to expect in the future," said University of Arizona paleoclimatologist Jessica Tierney, lead author of the research published in the journal Nature.

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.

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.

"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."