Berkeley, Calif. — CALIFORNIA has a reputation as a leader in battling climate change, and so when Pacific Gas & Electric and environmental groups announced a plan last week to close the state’s last nuclear plant, Diablo Canyon, and replace much of the electricity it generates with power from renewable resources, the deal was widely applauded.

It shouldn’t have been. If the proposal is approved by the state’s Public Utilities Commission, California’s carbon dioxide emissions will either increase or decline far less than if Diablo Canyon’s two reactors, which generated about 9 percent of the state’s electricity last year, remained in operation. If this deal goes through, California will become a model of how not to deal with climate change.

While Pacific Gas & Electric asserts Diablo Canyon would be replaced with other forms of clean, low-carbon power, nothing in the proposal would require the company to go that far. Instead, the plan, according to my organization’s calculations, would require the company only to invest in energy efficiency and renewables programs equivalent to about one-fifth of Diablo Canyon’s electricity output. Anything beyond that would be voluntary.

Nearly every time a nuclear plant has been closed, its energy production has been replaced almost entirely with fossil fuels, including in California. In 2012, when the San Onofre nuclear plant closed, natural gas became the main replacement power source, creating emissions of carbon dioxide equivalent to putting two million cars on the road.