Unraveling the Signals of Global Climate Change

摘要

Over the past 50 million years, Earth's climate has been on a wobbly but persistent march toward cooler conditions. A telltale sign is the dramatic overall increase in global ice volume and decrease in deep-sea temperature. One of the best measures of this trend has been the oxygen isotopic composition (δ~(18)O) of shells of ocean-floor microfossils extracted from deep-sea sediment cores. These δ~(18)O records, which simultaneously capture information regarding global ice volume and deep-sea temperature, are acquired in the vast majority of studies of past deep-sea conditions and have provided Earth scientists with critical paleoceanographic and pale-oclimatic insight.