"Historic Climatology and California Climatic Reconstructions A.D. 1670 to 1961," Journal of Interdisciplinary History 25 (2): 225-253, 1994.

Abstract Historic records reveal that over the centuries people living in California have experienced many extreme climatic events. Today's conditions of water rationing, increased electric bills, depressed segments of agricultural economy, and the state's high unemployment rate are, in part, a direct result of prolonged drought. It is projected that the ever-increasing concentrations of atmospheric carbon dioxide and other trace gases, the natural processes of climatic variability, and a projected doubling of California's human population by 2010 will significantly increase society's vulnerability to extreme climatic conditions. Indeed, recent events along the Mississippi River flood plain have raised our collective awareness of the potential for profound climatic disaster in the United States. An area of 25,000 square miles, a region greater than the size of Lake Michigan, was inundated, causing the deaths of more than 50 people and a conservative estimate of $15 billion in property damage. The magnitude of the destruction was unanticipated by hydrologists and government planners. These recent climatic events and historic accounts force us to question if similar disasters could occur in California and other states in the future. Clearly, there is a real and practical need to better understand the frequency, duration, and amplitude of climatic extremes.

The purpose of this paper is threefold: First, to briefly discuss the availability and value of historic records as proxy evidence for the reconstruction of California climate. Second, to present the results of a high resolution dendrohydrological reconstruction for the Santa Ana, San Gabriel, and Los Angeles rivers drainage systems. Third, evaluate the nature of extreme climatic events over the last 300 years using historic records and high-resolution climatic reconstructions.

In reviewing the literature on historic climatology for California, one is struck by the paucity of focused research. The work carried out to date consists of narratives of folk histories of extreme events, limited historic verification efforts associated with early dendroclimatic reconstructions, and general studies of extreme climatic events including floods and droughts. The paucity of research is probably related to the difficult and time consuming effort necessary to conduct extensive and intensive literature reviews of many different kinds of documentation, a lack of scholarly interest likely related to negativism directed towards it in earlier years, and the availability and abundance of accurate instrumental records over a long period of time. The results of a brief survey of the sources, reliability, and usefulness for verification of dendroclimatic reconstructions is presented below.