The Scientific Rationale for the Early Testing of Cloud Brightening Principles
Relevant to Geoengineering
Phil Rasch
Pacific Northwest National Laboratory
I will outline the science behind the "cloud whitening" strategy for Solar Radiation Management
type geoengineering, and describe why I think it might be an interesting test case to consider in
exploring geoengineering issues. I do not wish to leave the impression that full deployment of
such a strategy should be undertaken, nor that the outcome of full deployment will be uniformly
benign or beneficial. I do think that this strategy provides a concrete example in which the pros
and cons of Geoengineering research can be explored. I will argue that meaningful field studies
can be performed that will help in understanding critical components of the climate system, for
interpreting climate change in the past, projecting climate change in the future, and in identifying
the viability of this strategy for geoengineering to counter some of the consequences of
increasing concentrations of greenhouse gases.