According to the Intergovernmental Panel on Climate Change, every increment in warming will negatively impact terrestrial food systems globally (IPCC, 2022). The report states that major food-producing regions will experience loses due do climate extremes (IPCC, 2022). Over the last 30 years major crop yields have decreased by 4-10% globally, with climate change increasing climate hazards such as droughts, floods, and storms (IPCC, 2022). In order to see the effects, the changing climate is having of agriculture and rural agricultural communities, one can focus of the San Joaquin Valley in California. The San Joaquin Valley is an acute example an uneven distribution of impacts of climate change with valley being one of the poorest as well as most polluted in the United States (Espinoza et al., 2023).
About the San Joaquin Valley
- The San Joaquin Valley is one of the most productive agricultural regions on earth with over five million acres of farmland and producing over 400 different commodities (Espinoza et al., 2023).
- Producing 60% of the nation’s fruits and 30% of its vegetables, the environmental conditions of the San Joaquin Valley will have major implications for food availability in the United States (Espinoza et al., 2023).
- Agriculture accounts for 70% of land use in San Joaquin Valley although urban land has been steadily increasing (Hansen, Jurgens, & Fram, 2018).
- California has become 3°F warmer between 1949 and 2005, leading to a persistent decline in precipitation and runoff (Ganesh & Smith, 2018).
- Contains a population of over 3.9 million spread throughout eight counties (Ganesh & Smith, 2018).
Hazards and Vulnerabilities
A Diminishing Water Supply
Perhaps the largest threat to the San Joaquin Valley is the diminishing water supply, as the valley experiences widespread drought and groundwater overdraft (Espinoza et al., 2023). Extreme droughts in this region are especially worrying because the San Joaquin River Basin combined with the Sacramento River Basin are a freshwater drinking source for about 20 million people in central and southern California (Brekke, et al., 2004).
- During 2014 and 2015 California experienced a devastating drought which led to thousands of acres of perennial crops being ripped out, and forcing farmers to draw on underground water which is both unsustainable and expensive (Keppen & Dutcher, 2015).
- Between 2014-2015 2,455 private wells were reported dry, affecting over 12,275 residents (Barreau et al., 2017).
- Anthropogenic climate change has been liked to account for up to 30% of the drought conditions between 2012 and 2014 (Ganesh & Smith, 2018; Williams et al., 2015).
- Irregular temperatures have already caused observable changes in the yield from fruit trees because many factors such as flowering date changes are tied to temperature characteristics of the surrounding environment (El Yaacoubi, Malagi, Oukabli, Hafidi, & Legave, 2014).
- During dry years 53% of California’s applied water is used by just agriculture in the San Joaquin Valley, and with water becoming scarcer, the 25 billion USD worth of agriculture in this area is being put in jeopardy (Espinoza et al., 2023).
- During the droughts of 2007-2009 and 2011-2016, California’s agricultural sector alone lost more than 6 billion dollars, not to mention further stressing energy and water resources (Pu, Jin, Ginoux, & Yu, 2022).
- Climate models have projected major drying conditions over the southwestern United States through the rest of the twenty-first century (Cook, Ault, & Smerdon, 2015).
- This area of the United States is also projected to experience increases in heat waves due to climate change (Palipane & Grotjahn, 2018).
- During these major droughts central and southern California experiences higher levels of vegetation reduction which in turn creates dangerous “dust bowl” effects which lower air quality by sending particulate matter into the air (Pu, Jin, Ginoux, & Yu, 2022).
- Tropical Pacific Ocean sea surface temperatures have been indicated to help control the annual variability of precipitation in the southwest (Seager & Hoerling, 2014).
- Models have indicated that increased drying over continental interiors during the summer season is expected due to changes in tropical oceanic warming caused by climate change (Lau, Leetmaa, & Nath, 2008).
- Increasing pumping for groundwater due to drought has led to land subsidence with parts of the San Joaquin Valley sinking 28 feet which in turn leads to the permanent failure of many wells (Ganesh & Smith, 2018).
In order to combat these growing challenges major changes to the San Joaquin Valley are needed, with some projections stating that 10% (500,000 acres) of land may need to be transitioned from irrigated production to meet groundwater targets (Espinoza et al., 2023).
Erratic Weather Patterns
California is projected to experience unprecedented conditions ranging from extreme drought to intense deluge due to climate change (Maina, et al., 2022). Climate change events such as droughts have increased the reliance on the already thinly stretched groundwater in the San Joaquin Valley.
- Atmospheric rivers bring extreme precipitation when they make landfall, and atmospheric rivers are projected to increase in frequency about 30% by the end of the century (Espinoza, et al., 2018).
- Rising global temperatures will result in reduced snowpack storage in the watershed of San Joaquin River, leading to reduced stream flow and changing seasonal patterns, with hydrology shifting earlier in the water year due to rising temperatures (Kiparsky, et al., 2014).
- Rain on snow events are expected to increase in frequency in the coming decades, accelerating snowpack melt (Cayan, et al., 2018).
- By 2090 about half of April snowpack at the headwaters of the San Joaquin River are expected to disappear with spring runoff being reduced by 5.6 km3, important because reduced spring flows yield salinity increases (Knowles & Cayan, 2002).
- Annual salinity concentrations in the San Joaquin River have doubled since the 1940s, with much of this salt being pumped in from facilities in the Sacramento–San Joaquin Delta in order to irrigate crops (Quinn, Tansey, & Lu, 2021).
- Increasing salinity in groundwater in the San Joaquin Valley is projected to cost billions by 2030 in agricultural loss (Quinn, Tansey, & Lu, 2021).
Adoption of practices such as drip-irrigation would enable farmers to increase yields and use water resources more efficiently but are yet to become widespread (Abaci & Boz, 2022).
Vulnerabilities of the Community
The IPCC states that due to climate change the global hydrological cycle has intensified causing many impacts which are felt disproportionally by vulnerable people (IPCC, 2022). Already the water resources of the San Joaquin Valley are some of the most constrained in the nation (Brekke, et al., 2004).
- The San Joaquin Valley represents this very well with a water crisis being felt by a predominantly poor and minority community (Espinoza et al., 2023).
- Over 88% of farmworkers in the United States are Latino, with median earnings ranging between $10,000 and $12, 499 per year (Nunez, 2019).
- Urban areas in the San Joaquin Valley have some of the highest levels of ozone, which is a harmful greenhouse gas both to humans and the environment, in California.
- Because of its intensive agriculture, the valley contains two of the most contaminated aquifers in the nation and some of the highest nitrate levels in the country.
- Nitrate concentrations in the eastern San Joaquin Valley often exceed the drinking water standard (Dubrovsky et al., 1998).
- Nitrates have been found in 97% of wells sampled throughout the valley, and residents of San Joaquin Valley are 165% more likely to be exposed to polluted drinking water than the average California resident (Espinoza et al., 2023).
- Nitrate in drinking water is incredibly harmful and is associated with methemoglobinemia (“blue baby syndrome”) (Grout et al., 2023).
- Although the aggregate impacts of extreme weather events have been studied many times, one often overlooked impact is the mental health effects of events made more common by climate change.
- In California extreme weather events such as drought have been shown to negatively impact the mental health of residents, especially those who also rely on agriculture as a source of income (Barreau et al., 2017).
Farmers in the San Joaquin Valley have suffered from phycological impacts of drought, including solastalgia which is a loss of identity due to your home or a familiar place becoming unrecognizable due to a changing environment (Ganesh & Smith, 2018).
Although many of these impacts seem daunting, there are many ways to adapt to climate change and mitigate its effects.
- The state of California is implementing Water Evaluation and Planning (WEAP) modeling in order to asses the hydrological ramifications of different climate scenarios (Joyce, et al., 2011). This study found that improvements in irrigation efficiency through the adaptation of new technology and shifts in cropping patterns were both able to offset increasing water demands caused by increasing temperatures (Joyce, et al., 2011).
- In an attempt to mitigate the effects of air pollution and harmful ozone in the San Joaquin Valley, the State of California implemented a “Tune In & Tune Up” to provide residents free emissions tests and vouchers for emissions related repairs (California Regional Assessment Report).
- An ecosystem based adaptation strategy such as managing flood plains as an aspect of green infrastructure can have the benefits of both mitigation the effects of floods as well as providing benefits to native species such as fish and birds (Opperman, et al., 2017).
- Other mitigation practices that have shown promising results are flooding fields of crops in the winter in order to recharge ground water (Dahlke, et al., 2018; Ulrich et al., 2017).
These are a few examples of the many ways California is trying to adapt to the effects of climate change, especially in respect to the growing water crisis effecting both agricultural and the population of the region.
About the Author
Charlie Beams is from Andover, Massachusetts, and graduated in 2025 as an Environmental Studies major with a Statistics minor. He chose this project because of the importance of the Central Valley to the nation's food supply, and to look at how climate change is affecting this area of the country.
The San Joaquin Valley of California is an incredibly important area of the globe to examine when it comes to the impacts of climate change. The San Joaquin Valley has a large population of 3.9 million people who are predominately low income and Latino, experiencing some of the worst impacts of climate change in the lower 48. This valley is experiencing water shortages due to extreme weather such as drought and loss of snowpack in the mountains. These impacts have forced residents to rely increasingly on groundwater causing environmental and health issues. This is especially important because the San Joaquin Basin is part of a hydrological system that supplies over 20 million people with freshwater and supports one of the most productive agricultural areas in the world. Climate change is impacting the community in many ways and major action is required if this is still going to be either a viable place to live or grow food at the turn of the century.
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