Climate Engineering: Time For Drastic Measures?

Using mirrors to deflect the sun's rays from the earth might mitigate the effects of global warming — but is it worth it?

Sending tens of thousands of enormous mirrors into the Earth’s orbit may sound like a drastic or even laughable scheme to counteract the effects of global warming. But what about launching an even larger mirror from the moon’s surface, making an extremely long hose to spray sulfur into the stratosphere, or setting sail to hundreds of wind-powered boats to create artificial cloud cover? With the future of the world as we know it at stake, could these desperate measures be our greatest hope?

Speaking at a February 21 seminar on “geoengineering”—the practice of deliberately manipulating the Earth’s environment—Dr. Michael MacCracken of The Climate Institute contended that while reducing greenhouse gas (GHG) emissions is the best way to avoid the worst of global warming, certain climate engineering techniques may be justified as a last resort. However, he noted, most of these proposals would require international collaboration as well as continual maintenance, and would likely have adverse consequences, such as reduced daylight. In addition, he argued, such projects would place an unfair burden on future generations and run the risk of even greater catastrophe if emissions were allowed to build up and then the maintenance systems collapsed.

A more sensible compromise, MacCraken said, might be to target specific areas suffering the most from climate change, such as the Arctic. Reducing polar solar radiation by injecting aerosols into the atmosphere could slow the melting of sea ice and sea-level rise, benefiting both people and wildlife, he explained. The reduction of daylight would affect relatively few people in the sparsely populated region, and ozone depletion would be limited if the aerosols were kept low enough in the atmosphere. Such geoengineering could be an inexpensive, reasonable way to protect the Arctic while the rest of the world works to reduce GHG emissions, according to MacCraken.

Daniel Lashof of the Natural Resources Defense Council, also addressing the seminar, disagreed strongly with this perspective, noting that humans already know how to prevent the build-up of GHG emissions, so “why continue on a dangerous course?” He suggested three priority responses to the global warming threat: increasing energy efficiency, using non-fossil energy sources, and carbon capture and sequestration, an engineering solution that is better tested than most geoengineering methods. While not objecting to research into climate engineering, Lashof noted that such schemes fail to address other consequences of excess emissions, such as ocean acidification from an overabundance of carbon dioxide, and other potentially unknown effects of geoengineering. “What makes us think that if we’re not smart enough to avoid the problem, we’re smart enough to engineer our way out of it?” he asked.

This story was produced by Eye on Earth, a joint project of the Worldwatch Institute and the blue moon fund. View the complete archive of Eye on Earth stories, or contact Staff Writer Alana Herro at aherro [AT] worldwatch [DOT] org with your questions, comments, and story ideas.