Torrential storms soaked California and set off flooding across the state this weekend. The heavy rainfall was caused by one of the many atmospheric river events to hit the state this winter. Californians have seen hundreds of inches of snow in the Sierra Nevada mountains and rain elsewhere in the state since January. Atmospheric rivers, long, narrow bands of moisture in the atmosphere that extend from the tropics, are responsible for most of the flood damage in the United States. But climate change is increasing the moisture and precipitation carried by atmospheric rivers, escalating the threat of flooding, landslides, runoff and damage to infrastructure to communities.
A Pajaro River’s levee breach, flash floods, evacuations, power loss, and storm-related deaths plagued California over the weekend. Governor Gavin Newson has declared emergencies in over 30 counties and signed an executive order on Friday easing restrictions on capturing water from the storms. Also Friday, the Biden administration issued a disaster declaration for 35 counties and pledged funding for California’s emergency response. Californians are moving to collect this winter’s flush of water, but torrential rains and saturated landscapes won’t solve the Western region’s ongoing drought.
Years of dry weather has left parched soil compact, making it more difficult to absorb groundwater when it rains, leading to even more flooding and less water storage in the landscape. Many groundwater basins are also at record lows which would take more than just one wet winter to replenish adequately. This cycle is likely to continue, as climate change, caused by the extraction and combustion of fossil fuels, is poised to increase the pattern of dry, hot drought periods followed by heavy rainfall. (Snow: LA Times; Levees: AP, Washington Post $, NPR, Reuters, LA Times $, NPR, Bloomberg, NPR; Evacuations: AP; Deaths; The Hill; Power Loss: Axios, Washington Post $, Axios; Drought: Vox, E&E $; Climate Signals: Atmospheric rivers)
Correction: This story has been corrected to state that many California groundwater basins (not reservoirs) are at record lows.