Don’t Block the Sun to Cope with Global Warming

Modified jets spewing sulfuric acid could haze the skies over the Arctic in a few years “for the price of a Hollywood blockbuster,” as physicist David Keith of Harvard University likes to say. For a mere billion dollars a program to swathe the entire planet in a haze of sulfuric acid droplets could be ready as soon as 2020, he avers.

That’s geoengineering, or “the deliberate large-scale manipulation of the planetary environment,” as the U.K.’s Royal Society defines it. This hazing, which mimics the cooling effect of a volcanic eruption, is so cheap that almost any country—or any random billionaire—could afford to do it, if climate change got catastrophic enough that a crash course in cooling the planet came to seem a good idea. Already, a rogue geoengineer has tried to draw down atmospheric carbon dioxide by fertilizing the ocean with iron to promote the growth of photosynthetic plankton. That’s why the U.S. National Research Council empaneled a group of scientists and other experts to take a deeper look at a variety of geoengineering options in two reports released on 10 February—after all we may need them given the rising concentration of heat-trapping atmospheric carbon dioxide, which has now touched 400 parts per million.