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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.
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.
These proxy reconstructions are indirect inferences of temperature and thus tend to have greater uncertainty than instrumental data. Most proxy records have to be calibrated against local temperature records during their period of overlap, to estimate the relationship between temperature and the proxy.
A research question is "a question that a research project sets out to answer". [1] Choosing a research question is an essential element of both quantitative and qualitative research . Investigation will require data collection and analysis, and the methodology for this will vary widely.
For example, tree rings, ice cores, and corals generally show variation on an annual time scale, but borehole reconstructions rely on rates of thermal diffusion, and small scale fluctuations are washed out. Even the best proxy records contain far fewer observations than the worst periods of the observational record, and the spatial and temporal ...
Indicator bacteria themselves may not be pathogenic but their presence in waste may indicate the presence of other pathogens. [1] Similar to how there are various types of indicator organisms, there are also various types of indicator bacteria. The most common indicators are total coliforms, fecal coliforms, E. coli, and enterococci. [2]
They raised questions later adopted by critics of Mann's work, including the point that bristlecone pines from the Western U.S. could have been affected by pollution such as rising CO 2 levels as well as temperature. The temperature curve was supported by other studies, but most of these shared the limited well dated proxy evidence then ...