Bradley, R. S., H. F. Diaz, J. K. Eischeid, P. D. Jones, P. M. Kelley, and C. M. Goodess, 1987: Precipitation fluctuations over Northern Hemisphere land area since the mid-19th century. Science, 237, 171-175.
An extensive array of measurements extending back to the mid-19th century was used to investigate large-scale changes in precipitation over Northern Hemisphere land areas. Significant increases in midlatitude precipitation and concurrent decreases in low-latitude precipitation have occurred over the last 30 to 40 years. Although these large-scale trends are consistent with general circulation model projections of precipitation changes associated with doubled concentrations of atmospheric carbon dioxide, they should be viewed as defining large-scale natural climatic variability. Additional work to refine regional variations and address potential network inhomogeneties is needed. This study attempts to show secular precipitation fluctuations over hemispheric- and continental-scale areas of the Northern Hemisphere.