


“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.

Although an international treaty is a good long-term goal, Keith said a science agencies from international governments could come together this year and define some basic guidelines for how such research can and should be done. That sort of direction would help clarify the situation for researchers and funding agencies. Instead of focusing on specific projects and technologies, he and Parson argue that an international consortium could define two key thresholds.

The first threshold would outlaw the large-scale projects that scare people. They propose a numerical value for this threshold, which essentially amounts to ruling out experiments that could trigger climate change big enough to be detectable in the world’s temperature record—“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 that might involve, for example, releasing a few hundred pounds of a substance into the atmosphere and monitoring what happens in the atmosphere. Such experiments should be allowed, the scientists argue, because they perturb the environment far less than routine human activities such as airplane flights, fish farms, and sewage outfalls.

Keith, for example, is working on a proposal for an experiment that would measure ozone loss and involve releasing sulfur in the stratosphere. He noted that the project, which will not go forward without funding and public approval, is on a tiny scale when considering the 50 million tons of sulfur pumped into the atmosphere in a given year by a variety of sources.

Keith is president of Carbon Engineering, a Calgary-based company that is working on technology to capture carbon dioxide from the air and use it to create environmentally-friendly fuels. But he thinks that geoengineering efforts go far beyond the scope of simply removing carbon dioxide from the atmosphere, which is why they need more study and funding.

He notes that geoengineering experiments don’t get much support, especially in the U.S., where he says just a handful of research teams have been funded to specifically explore the potential of such technology by the National Science Foundation, a major funder of basic research. That potentially leaves scientists and policymakers in an uncomfortable place. If an emergency situation were to arise, in which a geoengineering technique could be valuable, the necessary basic research that would flesh out the viability and risks of geoengineering solutions would never have occurred. A range of potentially powerful scientific solutions would be risky and untested.

“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.