If 20 fire marshals came around and told us our houses were about to burn down, we’d buy some fire insurance. So when the leading science academies in 20 developed countries, along with several major American corporations and the national security community, all tell us that burning fossil fuels is causing dangerous changes to the climate, we think it’s time for the United States to get serious about clean energy. It also means supporting safely operating nuclear power plants that produce carbon-free electricity.

Already, 60 percent of our carbon-free electricity comes from the 99 nuclear reactors that dot the nation’s map, from Avila Beach, Calif., to Seabrook, N.H. These reactors provide low-cost, reliable electricity for the United States, which uses nearly 20 percent of the world’s electricity. But over the next decade, at least eight of these reactors are scheduled to shut down. That will push up carbon emissions from the American electricity sector by nearly 3 percent, according to the United States Energy Information Administration.

In California, the closing of the San Onofre Nuclear Generating Station in 2012 contributed to a 24 percent increase in carbon emissions from the electricity sector, according to data from the California Environmental Protection Agency Air Resources Board. Carbon emissions from the electricity sector in New England rose 5 percent in 2015, the first year-to-year increase since 2010, largely because of the closing of the Vermont Yankee Nuclear Power Station in December 2014, according to ISO New England, the region’s grid operator.

In roughly two decades, the United States could lose about half its reactors. That’s because, by 2038, 50 reactors will be at least 60 years old, and will face having to close, representing nearly half of the nuclear generating capacity in the United States. Without them, or enough new reactors to replace them, it will be much harder to reduce carbon emissions that contribute to climate change.