Climate Proxy

Observations of past climates are necessarily indirect. Hence, the main tool in the study of past climates involves climate proxies i.e. measurements in geological (e.g. lake or marine sediments, living or fossil coral reefs, cave deposits), glaciological (ice cores or snow pits) or biological (trees) archives. Many data streams can be collected from these archives, each sensing a different aspect of the environment (sometimes, several aspects at once).

Evans et al, [2013] define

- The sensor model may realistically be comprised of physical, chemical and biological components, and be multivariate, seasonal and/or nonlinear or thresholded in its response to environmental or climatic variation.

an archive is the medium in which the response of a sensor to environmental forcing is recorded (Fig. 1). Observations are made on archives.