Climate engineering: A critical review of approaches to modify the global energy balance

Abstract

Besides mitigation and adaptation, climate engineering, i.e. the large scale manipulation of the climate system has recently been promoted as a third strategy to combat the unwanted consequences of anthropogenic climate change. In this contribution, we address three climate engineering schemes that have been proposed. One scheme attempts to reduce the incoming solar radiation far outside the atmosphere, the other two increase the earth albedo either by introducing aerosols into the stratosphere or by modifying clouds in the lower marine atmosphere. While all three schemes face severe engineering challenges, they are in principle able to bring the global energy budget back toward the preindustrial value. However, this only holds for the global average, while unintentional regional climate response must be expected. The regional response is hardly predictable, and it is even rather difficult to detect in view of climatic variability. On the other hand, climate engineering would have severe ecological, societal, legal and political implications. We conclude that none of the schemes offers itself as remedy for climate change, but argue that dedicated research on their potential and consequences is advisable.