National Climatic Data Center, 15 July 2004

Paleoclimatic data, such as tree-rings, can be used to extend the climate record back several centuries beyond the 110-year instrumental record. Bald cypress tree-ring chronologies were used to reconstruct statewide spring (March-June) precipitation for Georgia (Stahle and Cleaveland, 1992). The tree-ring reconstruction explains 68% of the variance of Georgian precipitation. Reconstructed precipitation extends back to AD 933 and ends in 1985. Smoothed (10-year moving average) reconstructions show a range of variability in both drought intensity and duration over the past millennium. The 20th century part of the reconstruction is characterized by a high degree of variability and less severe droughts of shorter duration than the rest of the record. Two of the most persistent periods of droughts occurred around 1800 and in first half of the 12th century. The drought centered in the 1750s was also severe.

Reference:

More information on the Georgia and South Carolina tree-ring chronologies can be found in this publication:

Stahle, D.W. and M.K. Cleaveland, 1992, "Reconstruction and analysis of rainfall over the southeastern U.S. for the past 1000 years." Bulletin of the American Meteorological Society 73(12): 1947-1961.

Additional Resources:

These reconstructions are available from the NOAA Paleoclimatology Program web site:

http://www.ngdc.noaa.gov/paleo/recons.html#hydro