There may come a time where it would be immoral not to intervene to stop the Earth's temperature from rising. But engineering the climate by injecting particles into the stratosphere to reflect the sun's light is ambitious and risky. Before we do this, it would be important to know that the cure is not worse than the disease.
How to test the unknowns: The Earth system is complex. A path forward might include a series of experiments, with appropriate governance, that start at a very small (meter, kilogram) scale. Early work should not perturb the climate but rather teach us about, for example, potential chemical effects of injection.
Big questions: How are the benefits and costs balanced, economically, socially and morally? If rainfall increases in the Sahel but reduces in the Amazon, what do we do to compensate for those differences? These technologies could affect the most vulnerable, who are also likely to be the least culpable. How do we protect them?
Bottom line: One thing is clear, there is no rapid path back to pre-industrial equilibrium. If we do attempt to take control of the Earth's climate, we'll need to be more mindful, altruistic and empathetic as a species than we've been to date.
Other voices in the conversation:
- Janos Pasztor, climate policy expert and executive director, Carnegie Climate Geoengineering Governance Initiative: We aren't ready to engineer the climate
- David Dana, legal scholar, Northwestern University: Talking about geoengineering is distracting
- Jane Long, energy and climate scientist: It's time to investigate geoengineering technologies
- David Keith, climate and energy researcher, Harvard University: Solar geoengineering needs at least another decade of research