Climate Change is Transforming California Agriculture - But There are Ways to Adapt

By Patty Guerra, UC Merced

July 31, 2024

The special issue of PNAs was published this week.

California's agriculture faces challenges from a highly variable climate with temperatures that will increase over the next several decades. Droughts worsening and the Sierra snowpack, integral to the water supply, is volatile.

However, there are a number of ways to mitigate those changes, as outlined in in a new paper coauthored by a group of UC faculty.

The Proceedings of the National Academy of Sciences, a peer-reviewed journal of the National Academy of Sciences, published a special issue on "Climate Change and California Sustainability - Challenges and Solutions." It includes the paper titled "Cultivating Climate Resilience in California Agriculture: Adaptations to an Increasingly Volatile Water Future."

"Climate change impacts on productivity and profitability of California agriculture are increasing and forebode problems for standard agricultural practices, especially water use norms," lead writer Josué Medellín-Azuara, a UC Merced professor of environmental engineering, said in the paper. "In the face of clear conflicts among competing interests, we consider ongoing and potential sustainable and equitable solutions, with particular attention to how technology and policy can facilitate progress."

Though California's soil is among the most fertile on Earth, at first glance the state might seem a poor choice for farming: Much of the state doesn't see rainfall for six months of the year. But toward the beginning of the 20 ^th century, irrigation infrastructure and pumping allowed cultivation of water-intensive summer crops. Now the state produces $60 billion worth of agricultural products each year, according to the California Department of Food and Agriculture.

The multidisciplinary team of coauthors included economists Kurt Schwabe from UC Riverside and Daniel Sumner from UC Davis, agroecologist Amélie Gaudin from UC Davis, and water systems engineer Alvar Escriva-Bou, who works with both UC Davis and UCLA.

Researchers identified three key areas of action to help reduce California agriculture's vulnerabilities to climate change: water demand, water supply and the institutions that govern its use.

On the demand side, how and when water is delivered can have a major impact on how much is used.

"More efficient watering, fallowing land when needed and changing the crop mix will likely reduce overall water demand by agriculture," according to the paper, although the authors caution that proposed farm-level efficiencies may not lead to overall savings of any appreciable degree.

Over the past four decades, agricultural water use in California has decreased by nearly 15% while overall farm revenue has increased by nearly 40%, the researchers found.

On the supply side, researchers listed options that include better capture and use of flood water, maintaining healthy soils, and effectively monitoring and responding to extreme weather events. Groundwater recharge, water recycling and reuse, and desalination also provide opportunities to enhance supply. Another option, trading water with areas that have more of it, can help reallocate water supplies to reduce costs of both temporary and long-term shortfalls.

Institutions have a vital role to play in providing data, information and research.

"Investments in water-related data and information platforms have the potential for large payoffs by helping entities make more informed decisions," the researchers wrote. "By narrowing crucial information gaps, agencies may improve prospects for agriculture, ecosystems, and underrepresented communities as they confront less reliable and potentially lower overall, water supply allocations in the future."

Research and development conducted at universities, private businesses and government has saved resources and improved environmental outcomes, the researchers found. They advocate developing a coherent research agenda to better integrate climate projections, pest and disease forecasting, soil ecosystems, new genotypes and system designs into agricultural management.

"Though climate change presents a more variable and uncertain future, it provides opportunities to adapt agricultural landscapes to better steward the environment," the researchers wrote. "Bold measures are urgently needed as water availability limits have already been exceeded and adaptation pathways adequate to address these challenges require faster interventions than current trends. Approaches that decrease exposures to stress, reduce vulnerabilities, and enhance stress resistance and recovery, are important for California to address its climate change challenges."

The paper was partially supported by grants from the California Department of Food and Agriculture and the United States Department of Agriculture.

Patty Guerra