Climatostratigraphy

Authors: Martin J Aitken Stephen Stokes

Publish Date: 1997

Volume: , Issue: , Pages: 1-30

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Abstract

The initial framework for global Quaternary climate change and climatostratigraphy was that based on the advance and retreat of alpine glaciers Subsequently this was supplemented by observation of such climatic indicators as fossil pollen varves and loess In recent decades knowledge of past climate has been revolutionised by measurement of the oxygen isotope ratios of fossil microfauna in cores extracted from sediment on the floor of the deep ocean and detailed analysis of physical properties of continuous loess sequences and polar ice cores The oxygen isotopic variations observed in ocean cores define the major global warmcold transitions which characterise the glacial and interglacial stages the basic climatostratigraphic units An absolute timescale for the climatic variations is derived from the Milankovitch astronomical theory of climate Isotopic and other variations on higher resolution timescales have been obtained for the last glacialinterglacial cycle from the polar ice caps and some deep sea cores It is increasingly being realised that the frequently rapid climatic shifts between glacial stadial and interstadial substages are more pronounced than had previously been thought There is growing indication that the climatic predictions from ice core and oceanic sources are manifested terrestrially by climatic indicators such as those mentioned above thereby allowing linkage of Palaeolithic chronology with the timescales used Climate changes during the Quaternary period exhibit global synchroneity on millennial and longer timescales On multimillennial 10 ka timescales they are principally controlled by the solar radiation budget On shorter millennial and submillennial timescales the changes are likely to be modulated to a large extent by changing ocean circulation patterns and interactions between the oceans the cryosphere and the atmosphere Fine resolution analysis of ice core climatic proxies have demonstrated that late Quaternary climatic changes have occurred on occasions on timescales of relevance to human activities sometimes as short as decades

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