July 16th, 2012
To combat global warming, there have been suggestions to increase the albedo of (i.e. brighten) low-level marine clouds by deliberately injecting them with aerosols. Though such cloud seeding could mitigate global-mean temperature rise through the aerosol indirect effects, the full climate response to this geoengineering scheme is poorly understood. For example, one prior simulation of cloud seeding exhibited catastrophic rainfall decrease over the Amazon, while another showed moderate rainfall increase there.
In this paper, we describe results from a simulation of cloud seeding using the GFDL AM2.1 atmospheric model coupled to a mixed-layer ocean model. Using a version of the model that incorporates the aerosol indirect effects, we increase by five times the sea salt concentrations in the boundary layer over three marine tropical regions featuring persistent low level clouds.
This research sheds light on aerosol-cloud interactions and how they can affect the atmospheric circulation, and it may help guide future work on geoengineering.