California drought of 2012–2016
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| California drought of 2012–2016 | |
|---|---|
| Name | California drought of 2012–2016 |
| Location | California |
| Period | 2012–2016 |
| Causes | El Niño–Southern Oscillation variations; Pacific Decadal Oscillation; Arctic Oscillation; reduced Sierra Nevada snowpack; anthropogenic greenhouse gas forcing |
California drought of 2012–2016 The California drought of 2012–2016 was a prolonged multi-year hydrological event that produced record-low precipitation, diminished Sierra Nevada snowpacks, and historically low reservoir levels across California. The episode intersected with broader climate variability linked to the El Niño–Southern Oscillation, the Pacific Decadal Oscillation, and trends attributed to anthropogenic climate change, prompting emergency actions by state and federal authorities including Jerry Brown, the United States Department of Agriculture, and the United States Bureau of Reclamation.
Background and climatic causes
The drought followed variable precipitation during the 2010–2011 winter and coincided with persistent ridging associated with the so-called "Ridiculously Resilient Ridge" identified by researchers at institutions such as the Scripps Institution of Oceanography and NASA. Studies published by teams affiliated with the National Oceanic and Atmospheric Administration and the United States Geological Survey linked the event to negative phases of the Pacific Decadal Oscillation and shifts in the Arctic Oscillation, while attribution analyses from the Intergovernmental Panel on Climate Change and the American Geophysical Union explored the role of greenhouse gas warming. Snowpack declines in the Sierra Nevada and reduced runoff into the Sacramento River and San Joaquin River were exacerbated by unusually warm winters noted by researchers at the University of California, Davis and Stanford University.
Timeline and severity
The multi-year event began with below-average precipitation in 2012 and deepened through 2013 and 2014, culminating in extreme drought classifications by the U.S. Drought Monitor and declarations by Governor Jerry Brown and federal agencies including the United States Department of Agriculture. By 2014–2015, climatologists at NOAA and the California Department of Water Resources reported record-warm temperatures and the lowest combined reservoir and snowpack totals since instrumental records kept by the National Weather Service. The severe phase persisted until heavy precipitation associated with a strong El Niño and consecutive atmospheric river events in 2016–2017 eased conditions, as noted by analyses from California Energy Commission partners and researchers at the Scripps Institution of Oceanography.
Impacts on water resources and agriculture
Reservoirs such as Shasta Lake, Lake Oroville, Don Pedro Reservoir, and Trinity Lake dropped to historic lows, reducing deliveries from the Central Valley Project and the State Water Project and prompting curtailments under laws administered by the California State Water Resources Control Board. Groundwater extraction increased, accelerating subsidence documented by the United States Geological Survey and researchers from the California State University, Fresno. The drought strained Central Valley irrigated agriculture, affecting commodities tracked by the United States Department of Agriculture and specialists at the University of California, Davis, including reductions in almond and rice acreage and shifts in crop choices reported by the California Farm Bureau Federation.
Environmental and ecological effects
Ecological impacts included stressed populations of steelhead and chinook salmon in the Sacramento–San Joaquin River Delta and tributaries, with mortality events monitored by the California Department of Fish and Wildlife and the National Marine Fisheries Service. Wetland habitats in the Sacramento–San Joaquin River Delta and the Salton Sea experienced declines, influencing bird populations monitored by the Audubon Society and researchers at the Point Reyes National Seashore. Wildfire risk increased in Sierra National Forest and Los Padres National Forest, with major incidents observed by the United States Forest Service and state fire agencies such as the California Department of Forestry and Fire Protection.
Socioeconomic and public health consequences
Economic analyses by the Public Policy Institute of California and the Economic Research Service of the United States Department of Agriculture estimated multi-billion-dollar losses in agricultural revenue and employment impacts across counties like Fresno County and Kern County. Urban water suppliers including the Metropolitan Water District of Southern California and the San Francisco Public Utilities Commission implemented conservation measures and mandatory restrictions under orders from Governor Jerry Brown and the California State Water Resources Control Board. Public health concerns surfaced around drinking water access in small communities monitored by the California Department of Public Health and in tribal areas represented by organizations such as the InterTribal Council of California.
State and federal responses and water management
Responses included emergency proclamations by Governor Jerry Brown, emergency funding from the United States Congress, and operational changes by the United States Bureau of Reclamation and the California Department of Water Resources. Policy actions encompassed temporary restrictions administered by the California State Water Resources Control Board, incentives through the United States Department of Agriculture drought programs, and groundwater management reforms culminating in the Sustainable Groundwater Management Act passed by the California State Legislature. Infrastructure responses involved accelerated projects by entities such as the Metropolitan Water District of Southern California and storage and conveyance studies by the California Water Commission.
Recovery and long-term policy changes
Recovery following heavy precipitation and runoff in 2017 prompted assessments by the California Natural Resources Agency, U.S. Geological Survey, and academic centers at the University of California, Berkeley and Stanford University regarding resilience and adaptation. Long-term policy changes included implementation of the Sustainable Groundwater Management Act by local agencies, updated urban water conservation standards overseen by the California State Water Resources Control Board, and planning documents by the California Department of Water Resources and the California Energy Commission integrating climate projections from the Intergovernmental Panel on Climate Change. The drought shaped debates involving stakeholders such as the California Farm Bureau Federation, Sierra Club, tribal governments represented by the California Tribal Water Coalition, and federal partners including the Bureau of Indian Affairs.