Climate change is dramatically affecting virtually every aspect of life in the San Joaquin Valley and our surrounding mountains. Mostly because of a warming planet, state and region. In 2018, California published its Fourth Climate Change Assessment. This massive report surveys the impacts of climate warming with computer models and data. It paints a grim picture. Since then, the state has experienced four of the six hottest years on record spanning 2018 through 2021.
Joshua Viers, a professor of engineering at UC Merced, is focused on Valley impacts, “Every indication is that it will be much warmer in California as a whole and certainly much warmer in the San Joaquin Valley. We’re talking about four to six degrees Fahrenheit on average.
“This means that the minimum temperatures will be much warmer and the maximum temperatures in fact will be quite a bit warmer, and there will be more days greater than 90 degrees Fahrenheit, upwards of 30 days by the end of the century.”
The climate assessment found that, statewide, average daily high temperatures could rise by as much as 8.8 degrees Fahrenheit by the end of the century. For Fresno, that could mean 43 more days with highs exceeding 106 degrees.
By 2050, the average water supply from snowpack is projected to decline by two-thirds. UC Merced Professor Josue Medellin-Azuara says that will seriously affect the Valley’s agricultural economy, “Reductions in irrigated crop area are inevitable due to the needed reductions in consumptive water use that are needed to balance the groundwater basins. So that will be more challenging than the potential reductions in climate change only.”
He also concludes that Valley farmers could be growing different types of crops in the future to compensate for the loss of water resources, “There are changes in technology that could change the varieties that are grown so that they can adapt to those incremental effects of warming.
“I think much more important is the impact of groundwater regulations because that will limit the amount of groundwater that can be pumped during dry years.”
The warming climate in the San Joaquin Valley will be compounded by wildly varying weather patterns. Researcher Joshua Viers says that will present major challenges for public health and the economy of the region.
“Not only will it be much warmer but it’s anticipated that precipitation, while on average might remain the same, the extremes of precipitation are likely to be much more pronounced. So that we’ll have prolonged dry periods, droughts much like that of 2011 to 2016 as well as very wet periods such as the one we had in 2017. We’re starting to refer to this as the whiplash effect where we have the prolonged dry and the pronounced wet.
“Daniel Swain at UCLA, as well as others, has shown that the increased frequency of that will probably be twice as often. So being able to manage those extremes is going to be a challenge for our infrastructure and our institutions.”
Other factors, such as wildfires, are expected to complicate matters even more. Climate change models predict that by 2100 the state could experience wildfires that burn up to 178% more acres per year than current averages.
Nowhere is that truer than in our nearby mountains. The massive Creek Fire is a stark example. Our closest national parks have experienced large fires year after year. In Sequoia National and Kings Canyon National Park, wildfires in 2020 and 2021 alone killed an estimated 20% of giant sequoias.
The chief of resources and science for the park, Christy Brigham, describes vast burned areas without any cones or seeds present. Even more disturbing, researchers have discovered some sequoias had been killed in moderate and even low-intensity fire zones.
Conditions leading up to the ferocious 2020 fires have been building over the past century. Fire suppression has resulted in a tangle of undergrowth and forest floor litter that’s ripe for a lightning strike. Then came the exceptional five-year drought beginning in 2012, which hit hardest in the southern Sierra, home to most of Sierra’s giant sequoias.
Brigham says the big trees could survive the stress of climate change on their own, but the combination of forces could be life-threatening.
“Climate change made that drought more severe than past droughts, and climate change and the hot weather and the dry winters are continuing to stress these trees and make all of the vegetation and fuels drier and more liable to burn at high intensity and generate these crazy new fires that generate their own, whether they’re burning so hot. So, the interaction between climate change and fire is very serious for us in the Sierra Nevada.”