Proxy (climate research)
A climate proxy ( English proxy "proxy") is an indirect indicator of the climate , which in natural archives such as tree rings , stalagmites , ice cores , corals , sea or ocean sediments , pollen was recorded or human archives and historical records or diaries. Climate proxies can be used to reconstruct the climate of the past, when no instrumental record existed.
In order to obtain a quantitative picture of temperatures, precipitation or other past climatic conditions from a climate proxy, a transfer function , also called a climate proxy function , must be derived through calibration and verification.
- At the beginning there is the determination of the age of the examined archive and the chronological classification of the proxy data.
- A period of time is selected for which data of the climatic quantity sought is already available, for example instrumental measurement data. The proxy data is calibrated on the measurement data, that is, a functional relationship, the transfer function, is derived between proxy and measurement data.
- Using this transfer function, the expected climatic data is calculated from the proxy data for a further period of time for which data of the climatic variable is already available. The data calculated in this way are compared with the available data and a check is made to determine whether the calculation is sufficiently accurate; the transfer function is verified ,
- It is now possible to calculate approximate climate parameters from the proxy data for periods for which no measurement data is available.
- Information and Example of proxies at the NOAA (English)
- Information on proxies at Real Climate (English)