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Updates to the State of California Climate Change Assessment

September 10, 2018

The latest California Climate Change Assessment, drafted and released on August 27, 2018, by the State of California, projects multiple threats to human life and business from climate change in the coming decades. These threats include rising temperatures, longer and more frequent droughts, more damaging wildfires, and changes in the timing and form of precipitation.

The latest Assessment estimates an increase in average daily temperature of 5.6 degrees to 8.8 degrees by 2100, which could have staggering impacts on agriculture in California. For instance, the Assessment estimates that yields could decline by 2 to 11 percent as a result of the direct effects of temperature increase for many field crops, orchards, grains, grapes, and corn, whereas some crops like cotton and tomatoes may see slight increases in yield.

A more fundamental and nearer-term shift, however, could be the climate change impact on water supply. By 2050, the report projects that California’s water supply may decline by two-thirds. The Report predicts that Sierra snowpack will cease to reserve as much water for the summer, affecting the timing and location of water flow, potentially resulting in flooding in the winter and lower supplies in the summer. Rising sea levels may also increase salinity levels in the Sacramento-San Joaquin Delta, through which Northern California water supplies head south to cities and farms. 

Together, these two concerns will place additional pressure on projects to increase storage and conveyance capacity, such as the proposed Sites Reservoir in Northern California and the Twin Tunnels (or California WaterFix), to move water under rather than through the Delta. The Assessment also suggests that new management and legal structures will have to be developed to take advantage of the winter runoff, possibly by routing that water to recharge depleted groundwater aquifers.

The reduced availability and increased cost of water would have adverse downstream effects. For instance, an increase in water costs would raise the cost of corn, silage, and hay, which are major inputs for dairy cows and beef cattle. Shifting crops to those that can tolerate a changing climate and yet provide high value, moreover, would make growing low-value feed crops less common in California. This could lead to a decline in California’s dairy industry, which is now the largest in the nation.

The Governor’s Office of Planning and Research, the California Natural Resources Agency, and the California Energy Commission jointly prepared the assessment, which relies on existing research done by California’s universities. It can be read in full here.


This memorandum is a summary for general information and discussion only and may be considered an advertisement for certain purposes. It is not a full analysis of the matters presented, may not be relied upon as legal advice, and does not purport to represent the views of our clients or the Firm. Matt Kline, an O'Melveny partner licensed to practice law in California, Heather Welles, an O’Melveny associate licensed to practice law in California, and Dimitri Portnoi, an O'Melveny counsel licensed to practice law in California, contributed to the content of this newsletter. The views expressed in this newsletter are the views of the authors except as otherwise noted.

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