Lake Sediments Reveal the Long History of California’s Past Droughts:
Global warming is changing Earth’s climate.
While California will certainly warm, it remains uncertain whether precipitation amounts will increase or decrease. Water shortages, however, are almost certain as the loss of snowpack with rising temperatures reduces water storage and increases flashiness of runoff. Overpopulated and water-stressed, the Coastal Southwestern United States (CSWUS) already faces a perennial freshwater shortage. Rising temperatures, even without a decrease in precipitation amounts, will stress the region’s socioeconomic stability and water management practices. Critical to planning for and mitigating against future risks from drought in this highly variable climate requires a long perspective, longer than our instrumental records. Here, we present various decadal to multi-decadal resolved lake sediment records from the CSWUS used to reconstruct the history of drought. Importantly, these lake-based reconstructions extend our knowledge of hydroclimatic variability beyond the tree ring records, which, for the CSWUS are rarely longer than 1000 years. Moreover, tree ring records do not cover the driest and low-lying areas of the state where some of our largest cities are found. Our results indicate drought conditions of longer duration than anything observed in the tree-ring records. Regional comparisons indicate also that the tropical Pacific is linked to drought in the study region. Finally, our results highlight the complex relationships between climatic forcings and the region’s hydroclimate, often producing abrupt, sustained change. The paleoclimatic record allows us to study the longer perspective of drought frequency, magnitude, and duration in the context of changing forcings and boundary conditions. Learning from, and planning for, these extreme (paleo) droughts should be an important objective of our state’s water management program.
Our Presenter Dr. Matthew Kirby
Another 100's yr. Drought ?
Dr. Matthew Kirby was raised along the Susquehanna River in Binghamton, NY. He received a BA from Hamilton College, a MSc from the University of Colorado, Boulder, and a PhD from Syracuse University. Prior to landing a job at Cal-State Fullerton, he served as a post-doc at the University of Southern California. In 1992, he spent 38 days on the RV Polar Duke along the Antarctic Peninsula collecting sediment cores for his undergraduate thesis project. From that time on, Kirby knew he wanted to study Earth's climate history. Today, he studies past climate using lake sediments collected in the rare, but wonderful lakes of the coastal southwest United States
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