For instance, in the original hockey stick (ending 1980) the last 30-40 years of data points slightly downwards.
In order to smooth those time series one needs to "pad" the series beyond the end time, and no matter what method one uses, this leads to a smoothed graph pointing downwards in the end whereas the smoothed instrumental series is pointing upwards — a divergence (Climate Audit). Consequently, tree-ring width and tree-ring density, both indicators of tree growth, serve as useful proxies for temperature.
By measuring tree growth in ancient trees, scientists can reconstruct temperature records going back over 1000 years.
, but that doesn’t say very much about your region’s climate—the area’s average weather conditions over a long period of time (30 years or more).
A growing synchrony has been revealed in ring-width patterns of trees in response to global warming.
A multidisciplinary research team consisting of Russian and Spanish researchers, with the participation of a researcher from School of Forestry Engineering and Natural Resources at Universidad Politécnica de Madrid (UPM), has assessed the tree-ring width patterns of diverse conifer species in Spain and Siberia.The main conclusion was that ice core dates, in particular those ice cores relied upon the Greenland Ice Core Chronology 2005 ( by a collaboration including Earth scientists, dendrochonologists, and historians, the chronology of the Greenland North Eemian Ice Drilling core (NEEM) has been reassessed and re-dated, confirming that such an offset does indeed exist in the GICC05 timescale below AD 1000.The clinching evidence was provided by linking tree-ring chronologies to ice cores through two extraterrestrial events…If the tree has experienced stressful conditions, such as a drought, the tree might hardly grow at all in those years.charm.) and the relationships between it and climatic factors at elevation of 1950m, the sensitivity of tree lines in Changbai Mountain to climatic factors was assessed.