Science in Mind

With climate debate ‘a little bit stuck,’ a call for more cooperation

Large-scale projects that could temper or reverse the effects of climate change by blocking some incoming sunlight or manipulating the atmosphere have long been unpopular on two opposing fronts. On one side are those worried about the unintended consequences and doomsday scenarios that could be set off by careless experiments. On the other are those who believe such research is important, but to support it now will detract from the urgent need to cut greenhouse gas emissions that are driving global temperature rise.

The result, argues Harvard University applied physics professor David W. Keith, is an impasse: no government framework regulating when and how such research can be done, and very little funding for the work.

“We’re a little bit stuck,” Keith said. “What’s sort of strange is this is potentially as big, in a sense, in its potential impact on the world over a century as, say, engineering new life forms or nuclear weapons. But as of now, there’s much less attention paid to it.”


To move the debate forward, Keith and Edward A. Parson of the University of California, Los Angeles School of Law, published a policy perspective Thursday in the journal Science, presenting a practical solution that would help the science move forward safely.

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Although an international treaty is a good long-term goal, Keith said science agencies from international governments could come together this year and define guidelines, by delineating two key thresholds.

The first threshold would outlaw the large-scale projects that scare people — “a moratorium on anything big enough to be observable on a global scale,” Keith said.

They also propose a low threshold, beneath which everything would be allowable. This would include small-scale outdoor experiments.

“Of course we should cut emissions, but it doesn’t reduce all the risk,” Keith said. “And geoengineering has some real prospect” of making a difference.

Carolyn Y. Johnson can be reached at Follow her on Twitter @carolynyjohnson.