Drought: Past and Present - March 19, 2003 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Water is important to every resident of the arid southwest. Arizona is faced with a growing population and a limited water supply. We all need to learn how to conserve water in our homes, landscapes, and lives. This week, rather than discuss ways to decrease water consumption, lets look at a historic reconstruction of long-term drought conditions. I think you may find it interesting and, perhaps, sobering. The University of Arizona Tree Ring Research Lab has reconstructed our southwest climate going back over 1,000 years. Through dendrochronology (the study of tree rings), they utilize wood samples from living trees, dead wood samples, and archeological samples (beams and uprights in prehistoric structures). By measuring annual ring width in hundreds of samples, scientists have correlated the living and dead samples to reconstruct past climatic conditions. Tree rings are not perfect rain gauges, but they do respond clearly to extremes such as droughts. If you are interested, you can try tree ring reconstruction yourself on their web site: www.ltrr.arizona.edu. The following is a summary of their findings: Looking at cool-season precipitation (November-April) over the past 1,000 years, only 32 years in Arizona and 27 years in New Mexico had cool-season precipitation totals equal to or less than the 2002 cool-season precipitation. This tells us that if droughts occur entirely by chance, a value as low as the 2002 case might be expected about three times in a century. In Arizona, only 15 four-year periods since AD 1,000 were as dry as the last four years (1999-2002). However, some of these cumulative deficits lasted for more than four years. So, it could get worse! Four-year periods with similarly low cumulative totals to that of 1999-2002 were even more common in New Mexico since AD 1,000. It is important to note that warm-season precipitation totals also have been low over the last four years, exacerbating regional drought conditions. While not necessarily unprecedented in the last 1,000 years, the most recent drought has certainly been relatively unusual. The National Oceanic and Atmospheric Administration (NOAA) produces many weather and climate related products, including three-month and nine-month weather forecasts. NOAA predicts temperatures will be 10-20% above normal and precipitation will be 5-10% above normal March through May 2003. NOAA's long-term forecasts (April through September) are for 10-20% above normal temperatures and 5-10% above normal precipitation through June (beyond June, the reliability of their precipitation forecast is poor, so no prediction is made). If you would like to keep updated on the current state of knowledge of the long-term drought and weather predictions, then I encourage you to visit the CLIMAS web site at: www.ispe.arizona.edu/climas/. CLIMAS is the acronym for Climate Assessment for the Arid Southwest and is a part of the Institute for the Study of Planet Earth at the University of Arizona. This is truly a useful resource for understanding southwestern climatic conditions. I know some readers do not have access to the Internet, but the information resources available are mind-boggling. Some scientist's feel that we may be seeing the beginning of a long-term dry period that could extend for 20-30 years. My personal philosophy is to prepare for continued drought. Then, I will not get as disheartened if the drought continues and will be overjoyed if we get normal or above average precipitation. The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at mgardener@verdeonline.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://ag.arizona.edu/yavapai/anr/hort/byg/. Back to Backyard Gardener Home Page

Arizona Cooperative Extension Yavapai County 840 Rodeo Dr. #C Prescott, AZ 86305 (928) 445-6590

Last Updated: March 13, 2003 Content Questions/Comments: jschalau@ag.arizona.edu Legal Disclamer