If ever there was a question about how serious the consequences are from shutting down a nuclear power plant, it was dispelled with results of a study showing that electricity generating costs rose by $350 million during the year after the 2012 closing of the San Onofre nuclear plant in Southern California. Natural gas made up for much of the shortfall; as a result, carbon dioxide emissions rose by 9 million metric tons, which is equivalent to putting 2 million additional cars on the road.

The economic and environmental consequences of abrupt nuclear plant shutdowns � not only in California but also the possible premature retirement of nuclear plants in Florida, Illinois, New York, Ohio and Pennsylvania � are far greater and even more troubling than the current slow growth of new nuclear plant construction. The economists who conducted the study, Lucas Davis of the University of California-Berkeley and Catherine Hausman of the University of Michigan, say that for the foreseeable future the shutdown of existing nuclear plants has far greater relevance because it could mean the loss of thousands of megawatts of emission-free energy. And it would also cost thousands of jobs and the loss of hundreds of millions of dollars in revenue.

It is ironic, and also troubling, that without nuclear power � the largest source of zero-carbon electricity in the United States � it will be impossible to reduce emissions to safe and acceptable levels. When nuclear plants close, it is natural gas � and sometimes coal � that makes up the difference. Nuclear power does more than any other source of energy to curb carbon emissions, yet some politicians and anti-nuclear environmentalists want to shutter nuclear plants.

We need nuclear power to curb the use of fossil fuels, especially coal but also natural gas. Coal and gas combined account for 60 percent of the nation�s electricity supply. Both load the atmosphere with enormous quantities of greenhouse gases.

The prospect of jettisoning nuclear power should be an embarrassment to the environmental community. The 10 largest environmental groups oppose its use, despite the fact that nuclear power provides significant energy and environmental benefits to tens of millions of Americans.

These same groups contend that renewable sources and improvements in efficiency are all that�s needed to meet our energy needs and international carbon commitments. But solar and wind won�t get us even halfway to where we need to be because they provide only a small fraction of U.S. energy and need backup power from fossil fuels on days when the weather isn�t cooperating.

California is known for its aggressive support for renewable energy and energy efficiency, and we certainly need these resources to help solve our energy problems. But in the year after San Onofre shut down, wind supplied 5.2 percent of the state�s electricity, solar 1.5 percent and natural gas 46 percent. So, what is picking up the shortfall? Natural gas.

It would be folly for the United States to turn away from nuclear power. Industrializing countries such as China, India and Egypt see nuclear power as a way to raise their standards of living without adding to the burden of carbon emissions. U.S. companies can supply the reactors and expertise to help make this happen. Our country�s continuing involvement would also be good for nuclear safety and nonproliferation because it would allow the United States to remain at the head of the world�s nuclear table.

As the need for carbon-free electricity grows, and as our fossil-fuel plants require replacement, we cannot ignore the value of nuclear plants such as Callaway in Fulton and Wolf Creek in Kansas. We need to make good use of nuclear power instead of discarding such an important resource.