In California’s Fourth Climate Change Assessment, the San Joaquin Valley region includes all of San Joaquin, Stanislaus, Merced, Kings, and Tulare counties, plus parts of Madera, Fresno, and Kern counties. It stretches from Stockton in the north to Bakersfield in the south. About 4 million people live in this region. That’s a little over 10% of the state population. Because its agricultural economy is so intimately connected to the physical environment, climate change is going to have unusually profound effects on life in this part of the state. Part 1 focuses on air quality and heat in the Valley. Part 2 will tackle the incredibly complicated topic of precipitation – both drought and flooding.