Geoengineering, the science of altering climate to counteract the effects of greenhouse-gas emissions—for instance by spraying aerosol particles into the stratosphere to reflect sunlight—is extremely controversial. Among environmentally minded critics, the consensus has been that geoengineering’s unintended effects on ecosystems make it untenable, that it cannot be a substitute for reducing greenhouse emissions, and that it should not be pursued. Yet, given the lack of action on reducing carbon emissions and the apparent onset of irreversible climate-change symptoms, the argument for geoengineering is becoming stronger. Have we reached such a crisis point that we must take this drastic measure?
There is a better path to ending the pernicious effects of climate change, and that is to end climate change. It’s true that reducing carbon emissions—even beyond the difficulty of changing global consumption patterns—leaves at least a twenty year window between the time reduction happens and the time we would see an effect on climate. Yet, according to a new UN study, two other greenhouse gases, black carbon and ozone (largely products of methane and coal ash) dissipate far more quickly. Because their lifetime in the atmosphere is days to a decade, a crash program to reduce them could see immediate results.1,2 By itself, drastic reductions in black carbon and ozone could halve global warming by 2030, according to the report. The one-two punch of reductions in methane and coal ash simultaneous with reduction in carbon--needed to get long-term changes under control—is thus a far better response to climate change than is geoengineering.
Geoengineering is extremely dangerous because it would leave an altered atmosphere. Should we continue carbon emissions, under the impression that geoengineering will take care of our problems, ocean acidification would intensify, as the oceans continued to take in carbon.3 This would accelerate the destruction of delicate coral reefs, and cause wider harm to marine ecosystems. Other unintended consequences are likely to accompany any geoengineering intervention. For instance, aerosol particles would reduce the sunlight reaching earth and change vegetation-growth patterns. Seeding the oceans with iron particles to grow plankton that take in carbon dioxide is another suggested form of geoengineering. However, this scheme also would alter complex biological processes in known and unknown ways, with likely toxic impacts.4 Indeed, unpredictable, and potentially multiplying, effects on complex biological systems are a grave concern arising from geoengineering (as from climate change). Counteracting changes to the atmosphere by modifying the atmosphere even more compounds the interacting chain of problems.
Prevention, then, is a far, far better solution to climate change than attempting a cure likely to have all kinds of side effects, predictable and unpredictable. The UN report outlines the main steps necessary to reduce black carbon and ozone emissions: reduced use of fuelwood, livestock management to reduce methane, better diesel-particle filters, and improved biomass stoves and brick kilns, among other measures. Many of these impact developing countries most heavily. Yet that does not absolve wealthy countries, or quickly developing ones (notably China and India), from responsibility for drastically reducing carbon emissions, crucial because of their long-term impact. Wealthy and less wealthy countries would need to strike a deal to confront the crisis at different points.
Unfortunately, the political will that once existed regarding climate change has been largely dissipated by a succession of economic and political crises worldwide. It will probably take a major climate event, or a series of them, to ignite the kind of response needed. When that happens, geoengineering cannot be part of the solution. Some scientists have suggested a-ten year moratorium on even research into geoengineering,5 and this seems the best means for ensuring that we don’t get seduced, or panicked, into employing these methods as an “easy” solution. While awaiting the day when drastic action is possible, the sustainability community needs to pull together to ensure that the correct action eventually be taken, and to encourage whatever steps are possible now. A single message is needed: that the only sustainable path is to simultaneously implement the one-two punch of greatly reducing short term climate gases and carbon emissions.