经济学人下载:古气候学—先知水域

Throughout history, people have viewed springs as mystical.
纵观历史，人们都认为泉水是神秘的。

From the warm pools of Roman Bath, whence sheets of lead inscribed with prayers have been recovered,
从罗马浴场温暖的水池（刻有祈祷文的铅片在那里被发现）

to the gassy waters beneath the Oracle of Delphi that are thought to have stimulated the visions experienced by Apollo's sacred priestesses,
到德尔斐神谕下面的气体（被认为促使了阿波罗的神圣女祭司所经历的幻象）

these sites have been sought out for purposes of divination.
寻找这些地点的目的都是为了占卜。

With a modern twist, this is still happening, for Jason Ricketts of the University of Texas at El Paso thinks
随着现代科技的发展，这种情况仍在发生，厄尔巴索德克萨斯大学的詹森·里基茨认为

the remnants of ancient springs can be used to help monitor climates of the past by dating when warm and cold periods occurred.
古代泉水的遗迹可以用来帮助监测过去的气候，方法是确定温暖期和寒冷期的年代。

Dr Rickett's starting point is his assumption that, as ice ages end and the world warms up,
里基茨博士的出发点是他的一个假设—随着冰河时代的结束，世界变暖，

underground water flows will increase simultaneously all around the planet.
地球各地的地下水流量将同时增加。

Moreover, as water travels through the ground it dissolves and picks up minerals, particularly calcium carbonate.
此外，当水穿过地面时，它会溶解并吸收矿物质，尤其是碳酸钙。

When it subsequently bubbles to the surface, it deposits these minerals as a type of limestone called travertine,
当它随后冒泡在地表时，它将这些矿物质沉积为一种叫做石灰华的石灰石，

which has bands in it that reveal by their thickness approximately how long the water which created them was flowing.
石灰华中存在条带，可以通过它们的厚度显示出创造它们的水大约流动了多长时间。

The age of a band can be determined by analysis of the radioactive isotopes within it, particularly those of uranium and its decay products.
条带的年龄可以通过分析其中的放射性同位素来确定，尤其是铀及其衰变产物。

Dr Rickett therefore predicted that the thicknesses of bands of travertine of the same age from all around the world would be correlated,
因此，里基茨博士预测世界各地年代相同的石灰华条带的厚度是相关的，

and that those thicknesses would decrease and increase with the coming and going of ice ages.
并且这些厚度会随着冰河时代的到来和结束而减少或增加。

To test this idea he and his colleagues searched the scientific literature for all the previous studies of travertine they could find.
为了验证这一观点，他和他的同事们查阅了所有他们能找到的关于石灰华的科学文献。

By doing so, as they report in the Journal of Quaternary Science,
正如他们在《Journal of Quaternary Science》中的报告所述，

they discovered the ages of 1,649 deposits of the rock, scattered across every continent except Antarctica.
这么做让他们发现1649年的岩石沉积物，这些沉积物分布在除南极洲以外的所有大陆上。

To his delight, when Dr Rickett plotted these ages against the thickness of the bands reported,
令他高兴的是，当里基茨博士将这些年代与所报告中的条带厚度进行对比时，

he found that those thicknesses did indeed rise and fall in step.
他发现这些厚度确实是同步上升和下降的。

To his further delight, the dates he deduced for warm and cold periods matched those from the existing way of dating them,
令他更高兴的是，他推断出的温暖期和寒冷期的年代与用现有年代计算方式所得结果吻合，

which measures the ratio of isotopes of oxygen in fossil teeth—for this ratio is temperature dependent.
通过现有方式测算出了牙齿化石中氧同位素的比例—因为这个比值与温度有关。

That different dating methods have arrived at the same conclusion in this way
不同的年代测定方法以这种方式得出了相同的结论

is a useful confirmation that palaeoclimatologists' dates for events in the past few hundred thousand years are correct.
这有力地证实了古气候学家对过去几十万年事件的年代测定是正确的。