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Examples of proxies include stable isotope measurements from ice cores, growth rates in tree rings, species composition of sub-fossil pollen in lake sediment or foraminifera in ocean sediments, temperature profiles of boreholes, and stable isotopes and mineralogy of corals and carbonate speleothems. In each case, the proxy indicator has been ...
In statistics, a proxy or proxy variable is a variable that is not in itself directly relevant, but that serves in place of an unobservable or immeasurable variable. [1] In order for a variable to be a good proxy, it must have a close correlation, not necessarily linear, with the variable of interest. This correlation might be either positive ...
Global paleoclimate indicators are the proxies sensitive to global paleoclimatic environment changes. They are mostly derived from marine sediments.Paleoclimate indicators derived from terrestrial sediments, on the other hand, are commonly influenced by local tectonic movements and paleogeographic variations.
Examples of these conditions for coral include water temperature, freshwater influx, changes in pH, and wave disturbances. From there, specialized equipment, such as the Advanced Very High Resolution Radiometer (AVHRR) instrument, can be used to derive the sea surface temperature and water salinity from the past few centuries.
An important distinction is between so-called 'multi-proxy' reconstructions, which attempt to obtain a global temperature reconstruction by using multiple proxy records distributed over the globe and more regional reconstructions. Usually, the various proxy records are combined arithmetically, in some weighted average.
A paleothermometer is a methodology that provides an estimate of the ambient temperature at the time of formation of a natural material. Most paleothermometers are based on empirically-calibrated proxy relationships, such as the tree ring or TEX 86 methods.
Paleotempestology is the estimation of tropical cyclone activity with the help of proxy data. The name was coined by Kerry Emanuel of the Massachusetts Institute of Technology; [1] the field has seen increased activity since the 1990s [2] and studies were first carried out in the United States of America [3] on the East Coast.
A biological indicator is also the name given to a process for assessing the sterility of an environment through the use of resistant microorganism strains (e.g. Bacillus or Geobacillus). [5] Biological indicators can be described as the introduction of a highly resistant microorganisms to a given environment before sterilization , tests are ...