Deirdre Des Jardins, Director of California Water Research, has become a bit of a fixture at state agency meetings, such as the Delta Stewardship Council, Delta Independent Science Board, California Water Commission, and others. If you have attended these meetings, you’ve likely heard her speak during public comments. But who is she? I wanted to know more, so I sent her five questions.
Deirdre has done integrative synthesis of actionable science on climate change and California water issues since 2009. She previously did research on nonlinear dynamics and complex systems theory at NASA Ames Research Center, the Center for Nonlinear Studies at Los Alamos National Laboratory, and The Santa Fe Institute for Complex Systems. She describes herself as a teller of inconvenient truths about climate change impacts on California water, and has advocated for use of best available science in climate adaptation plans and related projects.
What inspired you to start California Water Research?
After the Delta Reform Act passed, I started researching the projections of impacts of climate change on California’s State Water Project and Central Valley Project. I have a background in physics — dynamical systems and complex systems theory. I’ve found systems thinking to be very helpful in thinking about climate change impacts.
In August 2012, I submitted our first detailed climate adaptation report to the Department of Water Resources as comments on their draft Climate Adaptation Strategy. The comments were titled, “Incorporating Drought Risk From Climate Change Into California Water Planning.” I cited the once in a millennium drought in Australia, and in the Southwest, and climate model projections of increased frequency and severity of droughts. I suggested that the drought could come to California.
The following year, 2013, was unprecedentedly dry. The Department of Water Resources staff said, “who could have known?” I thought, “Did you read the comments on your draft climate adaptation strategy?”
My 2012 comments cited some warnings from Department of Water Resources’ modelers about the limitations of DWR’s climate models and planning for risk. In retrospect this quote from a 2010 DWR report seems quite prescient: “there is a lack of analysis of potential drought conditions that are more extreme than have been seen in our relatively short hydrologic record. There is significant evidence to suggest that California has historically been subject to very severe droughts and that climate change could result in droughts being more common, longer, or more severe.”
What do you think is the most significant water issue facing California and why?
I frequently quote David Wallace-Wells, author of The Uninhabitable Earth. After the unprecedented flooding in British Columbia in 2021, he wrote “We aren’t just failing to address the growing climate crisis to come; we’re unprepared even for the impacts already here—in part because they keep surprising us with their intensity and in part because we can’t seem to fathom our genuine vulnerability.”
This is systemic in California’s climate adaptation planning. Most policy actors can’t seem to fathom our genuine vulnerability – to extreme heat, to drought, to flooding, to sea level rise.
We’ve advocated strongly for using disaster impact modeling to guide climate adaptation investments, and particularly for funding for the next phase of the ARkStorm 2.0 studies.
You have expressed concerns about DWR’s forecast models. What do you see as the problem, and what do you think they should do to address it?
There are two important studies that have come out this year. Christine Albano and researchers at the Desert Research Institute, together with Mike Dettinger at Scripps Institute, published a paper showing a big increase in evaporative demand in the Southwest and California. The increase in evaporative demand is two-thirds more than one would expect from temperature increases alone.
This increase in evaporative demand is forcing landscapes to extreme levels of dryness. Another study by Dana Lapides and researchers at the U.S. Forest Service research station in Davis is in preprint. They analyzed DWR’s snow data and 2021 runoff forecasts. They found that DWR’s overprediction of the runoff in 2021 is due primarily to unprecedently large root-zone storage deficits in the Sierra Nevada forests. Increased evaporative demand causes the forest to pull more water out of the root zone, and this creates a deficit that has to be filled before the mountain landscape will generate much runoff.
DWR’s climate change modeling also projects a slight increase in Sacramento River flows. The modeling may not fully capture these land surface / atmosphere interactions.
How do you think sea level rise will affect the Delta? How do you think the state could better prepare?
Over the near term, I’m more concerned about the risks of extreme river flooding. Climate modeling is showing that risks are increasing, and we’ve seen extreme flooding around the world in 2021 and 2022. Stockton has over 235,000 people in the 1 in 500 year floodplain, that will become the 1 in 200 year floodplain with climate change.
The state really needs to allocate more funding for flood risk reduction. We’ve also been advocating for hydraulic routing models to show in detail what areas could flood disaster and inform disaster preparedness.
Over the longer term, we need more 3-D hydrodynamic modeling to inform what will happen with salinity intrusion if and when Delta islands flood due to lack of investment by the state. The Department of Water Resources still hasn’t done adequate modeling of the performance of the proposed Delta tunnel intakes with sea level rise and island flooding in the North Delta, and the Central Valley Project will still be using the Jones pumping plant in the South Delta.
What role do you see for scientists in solving California’s water problems? How could science be better integrated into decision making?
This is an incredibly challenging time, and there are many good things happening. But Max Gomberg was right. Collectively, we are not facing hard truths and making the difficult decisions that need to be made. We need to create a space for state agency scientists to speak inconvenient truths about the impacts of climate change. And to be listened to.
I’ve also written about how the Delta Independent Science Board and the State Water Resources Control Board operate in the eye of the storm that is California water policy. The Governor needs to keep that eye stable, so there is space for independent peer review and making the hard decisions that need to be made in California management.
The Integrated Regional Water Management Plans are facilitating some good regional conversations around climate adaptation needs, which I saw in the 2021 IRWM Roundtable of Regions summit. But the discussions also showed how much regional climate adaptation networks need more advice and support from scientists on climate adaptation strategies.