Tomorrow the National Academy of Sciences will convene a workshop on geoengineering as a way to slow or reverse the effects of global climate change. Samuel Thernstrom thinks serious federal research on geoengineering is overdue.

A geoengineering system would of course be controversial, but the policy question we face today is simple: Should the federal government conduct research on geoengineering? The scientific and engineering challenges involved in geoengineering the global climate for decades, and the potential consequences of success or failure, are extraordinary; all the more reason to begin a research program commensurate with the scale and significance of the task.

Geoengineering is not a substitute for mitigation, and it raises potentially serious environmental and ethical issues. It could, however, protect us from the worst effects of warming for the many decades it will take for emissions reductions to become effective. We may ultimately decide that geoengineering's risks are too great -- but undertaking a research program now would give future policymakers the opportunity to make decisions about geoengineering from a position of knowledge rather than ignorance and desperation.

I am not sure whether geoengineering is a good idea -- or even whether it would be legal under existing international law without a new global treaty -- but I believe it is worth serious study. Humanity is altering planetary systems on a global scale whether we like it or not. Shouldn't we at least consider whether and how we can influence the climate in a positive -- or at least less harmful -- way? Even dramatic emission reductions won't eliminate humanity's effect on the climate system, so we should have all of our options on the table.