Abstract
Evidence is offered to demonstrate that past changes in sea level (eustasy) and oceanic 18O content are not direct measures of corresponding global ice volume changes and causal palaeoclimatic episodes. Geoidal eustasy is known to have caused non-synchronous eustatic changes in sea level over the globe. The hypothetical glacial expansion at around 115 000 yr BP, inferred from oceanic 18O records, is seriously questioned. It is proposed that expansions and contractions of the Arctic Ocean caused by geoidal eustasy significantly influenced the oceanic 18O records from time to time and were responsible for the isotopic substage 5d signal. Similarly, groundwater fluctuations in Africa and other equatorial areas affect the carbonate content of the oceanic records. Obviously, different impulses may lead to similar signals in records of supposed indicators of past climates. Such considerations must be borne in mind in analysing past climatic fluctuations as well as predicting future climatological events.
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