authored by Clark Miller, Arizona State University
Of all of the issues facing humanity at the moment, climate change is arguably the biggest. So, could the world’s smallest technology be the answer? This question was posed last month in the Proceedings of the National Academy of Sciences by David Keith, an engineering and physicist from the University of Calgary. Keith is a geoengineer—which is to say that he’s part of a small community of scientists who feel strongly that the world needs to explore technologies for deliberately engineering the Earth’s climate system to counteract the effects of climate change. Their contention, in a nutshell, has three parts: (1) The world is failing the test of reducing carbon dioxide emissions, as evidenced especially by the failure of the Copenhagen climate negotiations; (2) Global warming is accelerating, as are its impacts; and, therefore, (3) Perhaps scientists should be looking at ways to slow the pace of warming to give humanity a little more time to solve the problem of eliminating fossil fuels. Enter Keith’s latest idea: photophoretic levitation of engineered aerosols. What’s that you ask? The idea is relatively simple: design an engineered nanoparticle that has two properties. First, it reflects sunlight back into the air, increasing the Earth’s albedo and counteracting the effect of greenhouse gases. Second, in reflecting the sunlight, the particle uses a little bit of the energy from sunlight to levitate itself and move around. Put the right amount of these particles in the atmosphere, let them steer themselves to the right place in the Earth system, and voila, you reduce the amount of sunlight incident on the Earth and, hence, reduce the pace of global warming. Alright, so I’m a bit skeptical of this idea, for a variety of reasons. Nonetheless, I think it would make a great topic for science museums looking for a way to engage the public in nanotechnology. For one thing, it’s about saving the world. Nothing could be bigger and more important than that. But, even more important, this topic demands public engagement, dialogue, and deliberation. The geoengineering community grudgingly acknowledges this fact, but they’re worried that such a dialogue will largely take place in the absence of well-informed science. Science musuems are uniquely situated to ensure, on the one hand, that the discussions are informed by good science and, at the same time, that the public has an opportunity to learn about and think about this issue on their own terms and to have an honest dialogue about whether they think this is a really good idea or not. This would be a great topic for a national science café, for NanoDays, or for the new E-Cast network being pioneered by NISE.