Proxies stand in for direct measurements of past environmental conditions such as temperature, salinity, etc.
Measured climate information such as temperature is only available back to the late nineteenth century. To extend the record further back in history, proxies have to be used. Proxies are physical and chemical parameters that can be transformed through a calibration process to real measured variables such as temperature. From the ratios of stable oxygen isotopes in the carbonate shells of marine organisms, e.g., past temperatures can be reconstructed if the isotopic composition of the seawater is known. The information is stored in sediments of the shelf areas, continental margins and abyssal plains, and in the skeletons of tropical or cold-water corals. Environmental information can be obtained from the quantity and composition of organic matter, carbonate, and opal shells and from the species compositions of plants and animals. An overview of the use of...
KeywordsBenthic Foraminifera Planktonic Foraminifera Accelerator Mass Spectrometry Boron Isotope Biological Pump
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