Other more speculative approaches deserve consideration. In groundbreaking research, J. Eric Bickel, an economist and engineer at the University of Texas, and Lee Lane, a researcher at the American Enterprise Institute, study the costs and benefits of climate engineering. One proposal would have boats spray seawater droplets into clouds above the sea to make them reflect more sunlight back into space—augmenting the natural process where evaporating ocean sea salt helps to provide tiny particles for clouds to form around.

Remarkably, Mr. Bickel finds that about $9 billion spent developing this so-called marine cloud whitening technology might be able to cancel out this century’s global warming. The benefits—from preventing the temperature increase—would add up to about $20 trillion…

A technology-led effort would have a much greater chance of actually tackling climate change. It would also have a much greater chance of political success, since countries that fear signing on to costly emission targets are more likely to embrace the cheaper, smarter path of innovation.