Is California too dry, too wet, or both? Just weeks after greater Los Angeles was hit by January’s devastating wildfires, which were exacerbated by several months with almost no rain, a wetter-than-usual February brought flooding and mudslides to the region. The variability is just as pronounced on a year-to-year scale: The average annual rainfall at Los Angeles International Airport is around 360 mm, but several recent years, including 2023, have brought more than twice that amount, whereas others have had less than half. That weather whiplash, which isn’t confined to California, seems to be connected to anthropogenic climate change, so it’s expected to continue, intensify, and spread.1
Rainfall and surface water don’t tell the whole story. Groundwater is an important part of California’s water supply, not just in the agricultural Central Valley but also in urban areas, such as greater Los Angeles. Stored in the cracks of rock and...
