Living Reference Work Entry

Encyclopedia of Geochemistry

Part of the series Encyclopedia of Earth Sciences Series pp 1-8

Date: Latest Version


  • Jennifer E. HertzbergAffiliated withDepartment of Marine Sciences, University of Connecticut Email author 
  • , Matthew W. SchmidtAffiliated withDepartment of Ocean, Earth and Atmospheric Sciences, Old Dominion University


A paleotemperature is the temperature of a location, either on land or in the ocean, at a specific time in the geologic past. Scientists use paleothermometers to reconstruct past temperature records from archives – natural features of the Earth that preserve clues about past climate and environmental change. Examples of archives include marine and lacustrine sediment, glacial ice, and corals. Paleothermometers are often referred to as temperature proxies, which are measurable physical, geological, geochemical, or biological characteristics that get preserved in archives, standing in for instrumental measurements. Each proxy is associated with a calibration that transforms the proxy measurements into the parameter of interest, which in this case is temperature.

Scientists rely on proxy measurements from archives because direct observations of temperature extend back only as far as the middle of the nineteenth century (Smith et al. 2008). Direct temperatur ...

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