The San Joaquin Valley in California has experienced vast variability in climate extremes, with droughts and floods that were more severe and lasted longer than what has been seen in the modern record, according to a new study of 600 years of tree rings from the valley.
The researchers used the tree rings to reconstruct plausible daily records of weather and streamflow scenarios during the 600-year period.
This new approach, combining paleo information with synthetic weather generation, may help policymakers and scientists better understand – and anticipate – California’s flood and drought risks and how they will be compounded by climate change.
The group’s paper published in Earth’s Future , a journal of the American Geophysical Union.
The San Joaquin Valley sits in the southern part of California’s Central Valley, a major agricultural hub from which much of the nation gets its produce. Over the last few years, the region has seen a wild swing between severe drought and significant atmospheric rivers, which makes the valley a bellwether for the climate hazards that are facing the rest of California and much of the world, according to Patrick Reed , professor of engineering at Cornell University, and co-senior author of the paper.
The models show how flood and drought extremes have evolved within the San Joaquin Valley and can help clarify how natural variability and climate change can compound each other’s effects.
“Folks typically want to separate out internal variability versus climate change, just to get a sense of the signal change with anthropogenic warming,” Reed said. “But when we’re planning in complex water systems, both are occurring. And we need a sense of what happens when they come together. And what happens is we get extremes we’ve never seen. This opens the envelope of plausible futures in a much wider sense.”
Among the findings:
The research was supported by a National Science Foundation Graduate Research Fellowship.
For additional information, see this Cornell Chronicle story .
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Understanding the Contributions of Paleo-Informed Natural Variability and Climate Changes to Hydroclimate Extremes in the San Joaquin Valley of California
13-Nov-2023