has yet been proved to work at scale, and costs remain high. Even if costs come down, it will very likely remain more expensive than using fossil fuels without capture and storage, so a carbon price would be necessary for it to be applied broadly. A related idea is to reflect sunlight away from the earth so temperatures do not rise as much. This approach does not reduce the buildup of carbon dioxide in the atmosphere, and there is agreement that further research is necessary. If we use all of the fossil fuels in the ground, the planet will warm in a way that is difficult to imagine. Unless the economics of energy markets change, we are poised to use them. Michael Greenstone, the Milton Friedman professor of economics at the University of Chicago, runs the Energy Policy Institute there. He was the chief economist of President Obama’s Council of Economic Advisers from 2009 to 2010.
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