由于气候变化，北冰洋夏季的冰覆盖量现在仅是50年前的一半。
Because of climate change, the Arctic Ocean's summer ice cover is now half of what it was 50 years ago.
他希望，在楚科奇海域能钻探出几千年前的岩心，为了解海洋水流和冰之间相互作用提供详实的历史资料。
He hopes to drill cores that date back thousands of years at the Chukchi Sea margin, providing a detailed history of interaction between oceanic currents and ice.
49岁的布兰德从14岁就开始打猎，他说，大约20年前，当冬天海上的冰变得太薄，不再能够承受狗拉雪橇以后，猎海豹不再是这里一种持续的生活方式。
Brandt, 49, has been a hunter since age 14, and said roughly 20 years ago, when winter sea ice became too thin to support dogsleds, seal hunting ceased to be a sustainable way of life here.
在2000年前，南极冰川一直被认为处于平衡状态，融化流失的冰会和降雪达到平衡。
Before 2000, the ice on Antarctica is thought to have been roughly in balance overall, with new snowfall balancing ice lost through surface melt and icebergs.
沉积于冰前湖底或海底的细粒沉积物中间的大石块。
A large rock fragment, deposited in the midst of the fine-grained sediments on the floor of a proglacial lake or of the sea.
威勒斯列夫博士和（日后的）汉森博士从这块冰中找到了57种类群的DNA，包括真菌、植物、藻类与其他微生物，这些类群可追溯到4000年前。
Hansen discovered DNA from 57 species of fungi, plants, algae and other organisms, dating back as far as 4,000 years.
更多近期的地质研究证明了13000年前的冰川消退现象和整个加拿大不列颠哥伦比亚省主要沿海地区内无冰区的存在。
More recent geologic studies documented deglaciation and the existence of ice-free areas throughout major coastal areas of British Columbia, Canada, by 13,000 years ago.
在加拿大的育空地区，科学家们正在利用基因技术来鉴别北美驯鹿，并探究古时驯鹿的相关信息，6000年前它们曾在这块流冰区漫步。
In the Canadian Yukon, scientists are using genetic techniques to identify caribou and to study ancient caribou that roamed the same ice patches 6,000 years ago.
7亿年前地球上还没有植物，浑浊的冰（泥土和冰的混合物）可能是地球表面唯一能够吸收阳光的黑色物质。
Since plants had not yet evolved 700 million years ago, the dirty ice could have been the only dark spots on Earth's surface to absorb the sun's rays.
直到上个冰世纪末——约11000年前，人类才开始建立我们称为“乡村”的农村，当时人类已经存在大约12万年了。
Not until the end of the last ice age, around 11,000 years ago, did he start building anything that might be called a village, and by that time man had been around for about 120,000 years.
最近的证据支持了一个与长期存在的理论对立的观点，该理论认为，在1.1万至1.2万年前，美洲是由从白令海峡沿中大陆无冰走廊向南迁移的人殖民的。
Recent evidence favors a rival to the long-standing theory that the Americas were colonized 11,000-12,000 years ago by people migrating south from Beringia along a midcontinental ice-free corridor.
最近的证据支持了一个与长期存在的理论对立的观点，该理论认为，在1.1万至1.2万年前，美洲是由从白令海峡沿中大陆无冰走廊向南迁移的人殖民的。
Recent evidence favors a rival to the long-standing theory that the Americas were colonized 11,000-12,000 years ago by people migrating south from Beringia along a midcontinental ice-free corridor.
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