Good afternoon, committee members.
My name is Deirdre Des Jardins. I’m a consultant to the Institute for Fisheries Resources and the Pacific Coast Federations of Fishermen’s Associations on climate change and modeling, as well as the Director of California Water Research. My research background is in nonlinear dynamics and complex systems theory. I did research at the Center for Nonlinear Studies at Los Alamos, and the Santa Fe Institute.
I’ve worked on climate adaptation in the California water sector since 2010, advocating for use of best available science in climate adaptation.
In 2012 I made comments to the Department of Water Resources that the extreme drought in the Southwest could come to California, citing recent research. The next year it did.
In 2022 I made comments to the Water Board that the Department of Water Resources’ snow runoff forecasts had fatal flaws, in that they were based on analog years in the historic hydrology. The first half of 2022 turned out to be the driest 6 months on record. The California legislature requested an audit of the Department of Water Resources’ runoff forecasting based in part on my comments.
There has since been research by the US Forest Service that indicates that the source of the snow runoff forecast errors is related to increased Sierra forest root zone deficits.
In late 2022 I began a comprehensive literature review on the effects of climate change on Pacific Ocean/ atmosphere dynamics and California precipitation and temperature, reviewing over 1600 published papers. The more I looked at the literature, the more I realized that we’re in the middle of climate change. There was a regime shift in the Pacific Ocean in 1977, and there was a warmer, wetter period from 1977 to the next regime shift after the 1997/98 El Nino.
After the 1997/98 El Nino, there was a shift to a more La-Nina like pattern in the tropical Pacific, and a cold Pacific Decadal Oscillation pattern in the North Pacific. That was associated with a reduction of precipitation in January and February across western North America, and a megadrought in the Southwest.
I started doing a comprehensive analysis of California climate data. I found that the reduction in precipitation accelerated in 2013, and there was also a step increase in temperatures associated with hot droughts.
It’s clear that we’re no longer in the 20th century hydroclimate. The precipitation distribution has flattened out and there are more very dry and very wet years. And the dry years are much drier due to increased atmospheric thirst.
There has been intense research on the “pattern effect” of cool sea surface temperatures in the eastern Pacific. Climate model experiments indicate that the La-Nina like trend could be caused by slow recovery from anthropogenic aerosols, and that this will last for decades.
Research also shows that this “pattern effect” may have masked higher climate sensitivity. This is the subject of a major international research effort through the CLIVAR program, coordinated through the World Meteorological Association. This new research is the best available science, and I will get summaries of the research to the panel.
As far as adaptation, the water projects have been using “greedy” strategy and optimize operations to move as much water as possible in any given year to the San Luis Reservoir and reservoirs in Southern California. But this creates major risks of draining Northern California reservoirs to near dead-pool. We need to move to much more risk-based management, and also recognize that human systems have a much greater capacity to adapt to reduced surface water availability than ecosystems.
Further reading
Albano CM, Abatzoglou JT, McEvoy DJ, Huntington JL, Morton CG, Dettinger MD, Ott TJ. 2022. A Multidataset Assessment of Climatic Drivers and Uncertainties of Recent Trends in Evaporative Demand across the Continental United States. Journal of Hydrometeorology. 23(4):505–519. https://journals.ametsoc.org/view/journals/hydr/23/4/JHM-D-21-0163.1.xml.
DesJardins D. 2021 May 1. The “greedy” strategy for SWP and CVP reservoir operations. California Water Research blog. https://cah2oresearch.com/2021/05/01/the-greedy-strategy-for-swp-and-cvp-reservoir-operations/
DesJardins D. 2022 Mar 18. Fatal errors in DWR’s runoff forecasting: comments to the State Water Resources Control Board. California Water Research. https://cah2oresearch.com/2022/03/18/fatal-errors-in-dwrs-runoff-forecasting-comments-to-the-state-water-resources-control-board/
Hwang Y-T, Xie S-P, Chen P-J, Tseng H-Y, Deser C. 2024. Contribution of anthropogenic aerosols to persistent La Niña-like conditions in the early 21st century. Proceedings of the National Academy of Sciences. 121(5):e2315124121. https://www.pnas.org/doi/abs/10.1073/pnas.2315124121
Lapides DA, Hahm WJ, Rempe DM, Whiting J, Dralle DN. 2022. Causes of Missing Snowmelt Following Drought. Geophysical Research Letters. 49(19):e2022GL100505. doi:10.1029/2022GL100505. https://onlinelibrary.wiley.com/doi/abs/10.1029/2022GL100505
Lee S, Karnauskas K, Heede U, L’Heureux M. 2023. How the pattern of trends across the tropical Pacific Ocean is critical for understanding the future climate. ENSO blog. http://www.climate.gov/news-features/blogs/how-pattern-trends-across-tropical-pacific-ocean-critical-understanding-future.
Meehl GA, Hu A, Santer BD. 2009. The Mid-1970s Climate Shift in the Pacific and the Relative Roles of Forced versus Inherent Decadal Variability. Journal of Climate. 22(3):780–792. http://journals.ametsoc.org/doi/10.1175/2008JCLI2552.1
Mukhin D, Gavrilov A, Feigin A, Loskutov E, Kurths J. 2015. Principal nonlinear dynamical modes of climate variability | Scientific Reports. Scientific Reports. 5(1):15510. https://www.nature.com/articles/srep15510
Rugenstein M, Zelinka, Mark, Karnauskas, Kristopher, Ceppi, Paulo, Andrews, Timothy. 2023 Oct 31. Patterns of Surface Warming Matter for Climate Sensitivity. Eos. http://eos.org/features/patterns-of-surface-warming-matter-for-climate-sensitivity.
Williams AP, Cook BI, Smerdon JE. 2022. Rapid intensification of the emerging southwestern North American megadrought in 2020–2021. Nat Clim Chang. 12(3):232–234. https://www.nature.com/articles/s41558-022-01290-z
I agree that “the water projects have been using a “greedy” strategy to optimize operations to move as much water as possible in any given year to the San Luis Reservoir and reservoirs in Southern California. and that this creates major risks of draining Northern California reservoirs to near dead-pool, which is tantamount to death for salmonids, especially the endangered winter-rrun and spring-run Chinook salmon.
This is extremely well reasoned and well written. And should be given close attention by everyone, particularly organizations studying the climate as it moves forward.
Note the author’s credentials – having studied at Los Alamos and now having extensively reviewed papers addressing our changing climate. Not to be taken lightly.