Growing-season moisture variability in the eastern USA during the last 800 years

An 800 yr tree-ring-based reconstruction of the Palmer Hydrological Drought Index was used to document the frequency, severity, and duration of growing-season moisture anomalies (both wet and dry events) in the southern mid-Atlantic region of the USA. The data indicate that this region has experienced significant growing-season moisture variability (interannual to multidecadal) since A.D. 1185. Conditions during the 18th century were much wetter than they are today, and the droughts that occurred during the 16th century tended to be both longer and more severe. The recent growing-season moisture anomalies that occurred during 2002 and 2003 can only be considered rare events if they are evaluated with respect to the relatively short instrumental record (1895 to 2003). When compared to the 800 yr reconstructed record, neither of these events is particularly unusual. Growing-season moisture conditions during the 20th century appear to be well within the range of natural climate variability when compared to the 800 yr record.