|d18O from tree-rings and tree-ring width are proxies for both precipitation and temperature and show similar trends.|
Prior posts on non-hockey-sticks
Abstract: Few long and well-dated summer precipitation reconstructions that extend beyond the longest records of instrumental measurements exist in Europe. Further understanding of the past trends in summer precipitation and the mechanisms driving that variability are necessary to improve the predictions of climate models. Tree rings are unique in their ability to provide high-resolution, absolutely dated climate signals for the study of palaeoclimatology. The physiological processes controlling oxygen isotope composition (δ18O) in wood are reasonably well understood highlighting its potential as a climate proxy in a variety of environments. Significant correlation between wood δ18O and precipitation has been demonstrated worldwide reflecting both direct rainout processes and indirectly evaporative enrichment. We present an annually resolved reconstruction of precipitation based upon oxygen isotope variations in tree ring cellulose covering the most recent ˜400 years for England. The May-August precipitation series, which was formed by combining reconstructed values based on oxygen isotope composition (δ18O) in tree ring cellulose of pedunculate oak (Quercus robur) (1613-1893) and instrumental data (1894-2003), indicates significant decadal and centennial precipitation variability culminating in dry conditions in the early-middle 17th century and the late 20th century. The analysis demonstrated statistically robust May-August precipitation signal in the δ18O values of oak cellulose back to 1697, the first year of the oldest instrumental precipitation series in England.