There are an estimated 77,500 farms in California, the largest and most varied agricultural state in the nation. California produces over one-third of the country’s vegetables and two-thirds of its fruits and nuts. That critical food supply is at great risk of mostly vanishing as a result of the greenhouse gas emissions from our relentless burning of fossil fuels.
That is the finding of a new study published in Agronomy, in a recent paper by a University of California team led by Tapan Pathak of UC Merced. Climate change in California will have huge impacts on our food supply of almonds, pistachios, oranges, apricots, nectarines and prunes, more than a third of our vegetables, including artichokes, broccoli, spinach and carrots and other food crops.
Agricultural production in California is highly sensitive to climate change. Changes in temperatures and in the amounts, forms, and distribution of precipitation, increased frequency and intensity of climate extremes, and water availability are a few examples of climate-related challenges to California’s agriculture sector. Irrigated agriculture produces nearly 90% of the harvested crops in California and a decrease in water availability could potentially reduce crop areas and yields [3]. Permanent crops are among the most profitable commodities in California. They are most commonly grown for more than 25 years, which makes them more vulnerable to impacts of climate change. For California, as an agricultural leader for various commodities, impacts on agricultural production due to climate change would not only translate into national food security issues but also economic impacts that could disrupt state and national commodity systems.
The LA Times tells the sorry tale of a phenomenon that threatens a large portion of the food supply for the United States from just one American state. Also worrying for future food production is that climate change is threatening south and central Florida agricultural lands by sea level rise that poisons the state’s fresh water supply by salt water intrusion into the Floridan aquifer. Today, nearly 40% of the continental United States is in drought. And the high plains suffered a “flash drought” that destroyed up to 40% of the 2017 winter cereal crops.
Michael Hiltzik writes:
Among the chief manifestations of climate change will be changes in precipitation patterns, leading to more drought and more flooding, and spottier water storage. Generally warmer temperatures, not to mention more frequent and severe heat waves, will reduce yields of wine grapes, strawberries and walnuts; shorter chill seasons will make vast areas no longer suitable for chestnuts, pecans, apricots, kiwis, apples, cherries and pears. Plant diseases and pests will move into regions where they haven't been a problem before.
Few crops will escape the dire effects of the transformation. Seasonal chilling is necessary to break some crops out of dormancy and launch pollination and flowering. By the end of this century, according to a study cited by the UC paper, the shrinking winter chill period will reduce the acreage of the Central Valley suitable for chestnut, pecan and quince by 22%, and for apricot, peach, nectarine and walnut by more than half. By 2000, only 4% of the Central Valley was suitable for apples, cherries and pears, but none of that will be left by 2060 under almost any climate change scenario.
Put it all together, and the prospect is for a dramatic change in the mix of California produce and overall output. The UC paper foresees a decline of more than 40% in avocado yields, and as much as 20% in almonds, table grapes, oranges and walnuts. (Wine grape yields will be generally unaffected, but their quality might be compromised.)
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"Central Valley chill-sensitive perennial crops, especially the ones that require a higher number of chill hours, are vulnerable to climatological changes," Pathak says. "Heat-sensitive crops, such as strawberries and vegetables, drive vulnerability in coastal areas. Heat-stress-related vulnerability would greatly impact desert regions."
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