Although smog was never vanquished, California’s clean air fight in recent decades expanded to take aim at planetary climate change. The planet is heating up: all together, the past five years were the warmest on record, NASA reported in February. Average global surface temperatures have climbed about 2℉ since the 1880s, according to NASA. And there’s a scientific consensus that human activities — particularly ones that produce greenhouse gases — are the primary driver.
Cars belch out a bouquet of greenhouse gases, including refrigerants that seep from air conditioners. Most of all, though, cars pump carbon dioxide into the atmosphere, where it traps heat. The EPA estimates that one average car, in one average year, produces 4.6 metric tons of carbon dioxide (give or take, depending on the car, fuel, and distance driven). That may not seem like much, but with 25.6 million registered cars in California in 2018, it adds up. Passenger vehicles produced a bundle of greenhouse gases equivalent to roughly 119.9 million metric tons of carbon dioxide in 2017, according to the state air board’s latest numbers.