People are more familiar with things like tree rings and ice cores or ocean sediment cores.

人们更熟悉树木年轮、冰核或海洋沉积物核等东西。

Using a sediment core as a detailed history of climate change, scientists can see how the forested Arctic gradually became covered in ice and snow.

将沉积物岩心作为气候变化详尽说明，科学家们能够弄清草木茂盛的北极如何逐渐被冰雪覆盖的。

But the expedition was able to recover sediment cores stretching all the way down to the underlying rock-a thickness of 100 metres in some cases.

但是这次探险能够恢复一直延伸到地下岩石的沉积物岩心，在某些情况下其厚度达了100米。

Analyses of sediment cores have revealed that back then summers reached about 15 to 16 degrees Celsius, a good 8 degrees warmer than modern Arctic summers.

对沉积物岩心的分析显示，那时夏天气温能到约 15-16 摄氏度——比北极现在夏天气温至少高了 8 度。

While that study of sediment cores only looked at this cycle over the last 100,000 years, it was probably happening back in the Miocene Epoch, too.

虽然这项对沉积岩心的研究只关注了过去 10 万年的这个循环，但它很可能也发生在中新世时期。

So, researchers have also been looking at ocean sediment cores, which show what’s been piling up on the ocean floor over time, and can be sampled around the globe.

因此，研究人员也一直在研究海洋沉积物岩心，这些岩心显示了随着时间的推移在海底堆积的物质， 并且可以在全球范围内进行采样。

And that’s what this new research did, using data from 59 ocean sediment cores to estimate temperatures over the past two million years – back to the middle of the Pleistocene era.

这就是这项新研究所做的，它使用来自 59 个海洋沉积物岩心的数据来估计过去 200 万年的温度——可以追溯到更新世中期。