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Reconstructions of global temperature of the past 2000 years, using composite of different proxy methods. In the study of past climates ("paleoclimatology"), climate proxies are preserved physical characteristics of the past that stand in for direct meteorological measurements [1] and enable scientists to reconstruct the climatic conditions over a longer fraction of the Earth's history.
John Imbrie (July 4, 1925 – May 13, 2016) was an American paleoceanographer best known for his work on the theory of ice ages. He was the grandson of William Imbrie, an American missionary to Japan. After serving with the 10th Mountain Division in Italy during World War II, Imbrie earned his bachelor's degree from Princeton University.
Paleoceanography makes use of so-called proxy methods as a way to infer information about the past state and evolution of the world's oceans. Several geochemical proxy tools include long-chain organic molecules (e.g. alkenones), stable and radioactive isotopes, and trace metals. [1]
Proxies of global climatic significance are, however, less ambiguous in paleotemperature interpretation. Marine biota have offered by far the most proxies for paleotemperature, of which the microfossils, because of their widespread, abundance and sensitive to latitudinal changes, have provided many primary important paleotemperature indicators.
For recent proxy archives of tree rings and corals the individual year rings can be counted, and an exact year can be determined. Radiometric dating uses the properties of radioactive elements in proxies. In older material, more of the radioactive material will have decayed and the proportion of different elements will be different from newer ...
Also called Indianite. A mineral from the lime-rich end of the plagioclase group of minerals. Anorthites are usually silicates of calcium and aluminium occurring in some basic igneous rocks, typically those produced by the contact metamorphism of impure calcareous sediments. anticline An arched fold in which the layers usually dip away from the fold axis. Contrast syncline. aphanic Having the ...
Five million years of glacial cycles are shown, based on oxygen isotope ratio believed to be a good proxy of global ice volume. The MPT is the transition between the periodicities shown in green. The Mid-Pleistocene Transition ( MPT ), also known as the Mid-Pleistocene Revolution ( MPR ), [ 1 ] is a fundamental change in the behaviour of ...
John Williams Valley (born February 28, 1948, in Winchester, Massachusetts) is an American geochemist and petrologist. He is an expert on stable isotope geochemistry, [ 1 ] especially as applied to understanding the evolution of the Earth's crust .