The Case for Geoengineering Research

If the climate's sensitivity to increased greenhouse gases is high, it may be too late to avoid dramatic consequences for humans and natural ecosystems, even if we cut emissions to zero instantaneously. Emissions cuts are necessary, but they are not sufficient to manage climate risks; prudence demands that we study methods that can limit the environmental risks posed by the accumulation of fossil carbon in the atmosphere. I will argue that systematic management of climate risks requires the capability to geoengineer; and will discuss the science, engineering and policy aspects of a research program that might develop the capability to deliberately increase the earth's reflectivity. Solar geoengineering has three essential features: it is cheap, fast and imperfect. I will describe how these features may shape decisions about research and implementation.