Researchers' clues to the Eemian climate come from measurements of the ratios of two slightly different types of oxygen, isotopes oxygen-16 and oxygen-18, preserved in the GRIP core.

研究人员对间冰期气候的线索来自保存在 GRIP 冰芯中的两种略微不同类型的氧——即同位素氧-16和氧-18的比率。

youdao

Most hydrogen and oxygen atoms in water are stable, but traces of both elements are also present as heavier isotopes.

在水中大多数氢原子和氧原子是稳定的，但这两个元素也有微量以较重的同位素形式存在。

youdao

By measuring the proportion of heavier hydrogen and oxygen isotopes along a strand of hair, scientists can construct a geographic timeline.

通过测量一束头发上较重的氢和氧同位素的比例，科学家可以构建一个地理时间轴。

youdao

To find out how warm the earth was before that, climatologists have had to resort to indirect methods, such as measuring tree-rings, or counting the different isotopes of oxygen in layers of polar ice.

ECONOMIST: The hole story of global warming

The researchers looked at the different types, or isotopes, of oxygen atoms trapped in the samples and, using a well-established technique, were able to infer water temperatures at the time the organisms built their shelly parts.

BBC: Dinosaurs felt the heat