Ahrens, C. Donald. Meteorology Today: An Introduction to Weather, Climate, and the Environment. 7th ed. Pacific Grove, Calif.: Thomson Brooks/Cole, 2003. National Weather Service, National Oceanic and Atmospheric Administration, home page. Available online. URL: http://www.nws.noaa.gov/. Last modified September 15, 2008. Data updated continuously.
paleoclimatology Paleoclimatology is the study of past and ancient climates, their distribution and variation in space and time, and the mechanisms of long-term climate variations. A wide variety of different types of data are used to determine past climates, such as the distribution of certain plant and animal species that are climate sensitive and the distribution of certain rock types that form in restricted climate conditions. other types of data serve as paleoclimate indicators, including tree-ring studies (dendrochronology), ice-core data, cave deposits (speleothems), and lake sediment studies. Increasingly, studies are using isotopic data, such as ratios between light and heavy oxygen isotopes, as paleoclimate indicators since these ratios are very sensitive to past global climates, glaciations, and elevations at which rainwater fell.
Most paleoclimate studies reveal that there have been major climate shifts on the planet throughout Earth history, with periods of near global glaciation, periods of intense heat and humidity, or hot and dry weather, and more temperate periods such as the current interglacial stage. Many factors play a role in climate change, including orbital and astronomical variations described by Milankovitch cycles, plate tectonics and the distribution of continental land masses, and volcanic productivity.
Paleoclimate studies have been used widely by scientists who study the past distribution of continents in supercontinents and continental drift. For instance, if a continental land mass moves equatorial regions to more polar regions, it will experience a progressive shift in the surface climates. Any rocks deposited during these different climates will reflect the climatic conditions that prevailed during that time period, and any plant or animal fossils in the rocks will reflect species that were able to survive under the prevailing climate conditions. Thus, studying the rock record reveals information not only about the past climates for a continental block, but also the history of climate zones that a plate or continental block moved through during its drift across the surface of the Earth.
See also climate; climate change; Milanko-vitch cycles; plate tectonics; supercontinent cycles.
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