A number of geoengineering schemes have been percolating throughout the scientific community and the media as potential solutions to climate change. Warming could be slowed by injecting sulfur into the atmosphere to reflect sunlight. Adding iron to the ocean could promote algal blooms that would help sequester carbon dioxide. Giant mirrors could reflect light away from Earth.
In an essay in this week’s Nature Geoscience, phytoplankton ecologist Philip Boyd, at the National Institute of Water and Atmospheric Research, in New Zealand, urged the scientific community to seriously evaluate these geoengineering schemes and toss out the clear losers.
IEEE Spectrum ’s Monica Heger talked to Boyd about the different geoengineering ideas, how they should be evaluated, and when, if ever, we should use them.
IEEE Spectrum: Why do you think these geoengineering schemes need to be examined now?
Philip Boyd: Well, these schemes are continuing to proliferate, and at some point the scientific community has to look at them carefully. A number of these ideas have never been tested, yet if you look in the popular literature, they receive a disproportionate amount of attention. There are very complex issues associated with geoengineering, so we really have to think carefully about it. Some ideas clearly aren’t going to work.
With the publication of the recent Stern Review on the Economics of Climate Change—a British report estimating the cost of not mitigating climate change—and also some recent modeling studies, it does seem that time is not on our side.
Therefore, it would be useful to rank these geoengineering schemes and then focus on one or two that show the most promise. And after we’ve done that, put the rest of them to bed once and for all.
Spectrum: Can you describe the criteria used to judge the different techniques and how you weigh the criteria?
PB: Well, this is a difficult issue because there are so many unknowns. What we’ve tried to do is identify the four criteria that are the most important, which are efficacy, cost, risk, and time.
So, under effectiveness, there’s the actual rationale for the idea. In some cases the schemes are just based on theory, and in other cases they have a bit more meat to them; there is actually some precedence. For example, the group that’s keen to push ahead with the injection of sulfur particles into the atmosphere, they’ve based some of their evidence on data from volcanic eruptions.
For cost, people have come up with cost estimates, and in most cases they’ve all been overoptimistically low. What we’re saying is we really have to look at the potential side effects, and those have to be built into cost.