A critical assessment of proxy data for climatic reconstruction
Gordon Manley devoted most of his time and his indefatigable zeal to reconstructing climatic records extending as far back as possible; his classic article of 1974 is one of the most quoted papers. The number of reliable observation series for climatic reconstruction before about 1850 is limited, and in many areas of the globe there are no series for this period. Investigations on climatic variability are only meaningful if they are based on data series which are homogeneous and representative. Phenological data have also been used for climatic reconstruction. The use of proxy data series for climatic reconstruction depends first on a careful comparison with simultaneous observations from a truly representative climatic station. If proxy data are sufficiently homogeneous, they can even be used for testing the homogeneity of old climatic records. Controversy has focused on the cause of climatic change with respect to the ‘Little Ice Age’.