dendroclimatology

thumb|496px|Variation of tree ring width translated into summer temperature anomalies for the past 7000 years, based on samples from holocene deposits on [[Yamal Peninsula and Siberian now living conifers.]]

Dendroclimatology is the science of determining past climates from trees (primarily properties of the annual tree rings). Tree rings are wider when conditions favor growth, narrower when times are difficult. Other properties of the annual rings, such as maximum latewood density (MXD) have been shown to be better proxies than simple ring width. Using tree rings, scientists have estimated many local climates for hundreds to thousands of years previous. By combining multiple tree-ring studies (sometimes with other climate proxy records), scientists have estimated past regional and global climates.