THE DIABLO CANYON nuclear power plant lies about 200 miles north of Los Angeles on California's central coast. Its twin reactors sit between the Pacific Ocean on one side and emerald hills on the other. The Golden State’s only remaining nuclear plant provides nearly 9% of its electricity generation, and accounts for 15% of its clean electricity production. Yet despite California’s aggressive climate goals and a national push to reach net-zero emissions by 2050, Diablo Canyon is set to close down by 2025. A new report from researchers at Stanford University and the Massachusetts Institute of Technology (MIT) reveals just how detrimental that would be.

Diablo Canyon came online in 1985 and has operated without incident ever since. But the plant has not been uncontroversial. Diablo sits near several major fault lines, and locals have long feared that an earthquake could trigger a nuclear disaster. America’s Nuclear Regulatory Commission (NRC) ordered utilities to evaluate their nuclear plants for flooding and seismic risk in the wake of the meltdown at the Fukushima Dai-ichi nuclear plant in Japan in 2011. Diablo Canyon was found to be safe.