The 100,000-Year Ice-Age Cycle IdentiÞed and Found to Lag Temperature, Carbon Dioxide, and Orbital Eccentricity
The deep-sea sediment oxygen isotopic composition (d18O) record is domi-nated by a 100,000-year cyclicity that is universally interpreted as the main ice-age rhythm. Here, the ice volume component of this d18O signal was extracted by using the record of d18O in atmospheric oxygen trapped in Ant-arct...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.462.7435 http://mastergeosciencesocean.univ-brest.fr/_media/shackleton-2000.pdf |
| Summary: | The deep-sea sediment oxygen isotopic composition (d18O) record is domi-nated by a 100,000-year cyclicity that is universally interpreted as the main ice-age rhythm. Here, the ice volume component of this d18O signal was extracted by using the record of d18O in atmospheric oxygen trapped in Ant-arctic ice at Vostok, precisely orbitally tuned. The benthic marine d18O record is heavily contaminated by the effect of deep-water temperature variability, but by using the Vostok record, the d18O signals of ice volume, deep-water tem-perature, and additional processes affecting air d18O (that is, a varying Dole effect) were separated. At the 100,000-year period, atmospheric carbon diox-ide, Vostok air temperature, and deep-water temperature are in phase with orbital eccentricity, whereas ice volume lags these three variables. Hence, the 100,000-year cycle does not arise from ice sheet dynamics; instead, it is probably the response of the global carbon cycle that generates the eccentricity signal by causing changes in atmospheric carbon dioxide concentration. It has long been apparent that there is an;100,000-year (100-ky) cyclicity in d18O |
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