Paleoclimatology is the study of Earth’s past climate. Because there is no way to directly measure past climates, paleoclimatology relies on proxy measurements to aid reconstructions of historical conditions. Such measurements can include isotopic signature analysis—for example of δ¹⁸O and δ¹⁷O. These analyses take advantage of how variations in climatic conditions differentially affect isotopic abundance to reveal factors such as past temperatures or precipitation levels. Isotopic signature data can be gleaned from historical water samples, such as ice cores, or in certain organism remains, such as seashells. 

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