There is evidence in this ice-corerecord of seven periods when the ice caps expanded, and each of them shows a steady decline in the level of greenhouse gases after the ice receded again.
The Quelccaya icecore, drilled just 125 miles from Lake Titicaca, contains an annual record of precipitation for the region.
从提提卡卡湖125英里深处钻取的奎卡亚冰岩芯记录了该地区的年降雨量。
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Thee next step will be to point to a single piece of the geological record (an icecore, perhaps, or samples from lake sediments) that can serve as the officially accepted reference point.