PNNL

Abstract

Geoengineering has been suggested as a theoretical response to anthropogenic global warming. However, geoengineering has not been conducted, so there are no data or observations of it. How then can geoengineering be studied? One obvious technique is to use global climate models ("indoor" research) to simulate various proposed geoengineering schemes, such as adding aerosols to the stratosphere to reflect incoming sunlight or adding sea salt to marine stratus clouds to brighten them. Since these two techniques mimic volcanic eruptions and ship tracks, another suggestion is to study those phenomena as analogs to geoengineering. There have also been several suggestions for field experiments, as well as some small scaletests ("outdoor" research), to learn about geoengineering. In this article, we review these different research methods, commenting on their utility, safety, ethics, and governance. We also discuss natural analogs for geoengineering, such as the 1991 eruption of Mt. Pinatubo and the observation of ship tracks, highlighting both their utility in learning about the effects of geoengineering and their limits in providing knowledge. As we will demonstrate, geoengineering research is inseparable from climate research.