John Latham is working with several collaborators (including Prof. Tom Choularton, University of Manchester, UK; Prof. Stephen Salter, University of Edinburgh, UK; and Prof. Mike Smith, University of Leeds, UK) on a proposed geo-engineering technique for global warming mitigation (Latham, 1990 and 2002 , Bower et al. 2006). A detailed account of this work is presented in the three papers linked, above.

The basic principle of the scheme is advertently to increase the droplet number concentration N in maritime stratocumulus clouds, thereby increasing their albedo (reflectivity) for incoming sunlight and also their longevity. This would produce a cooling effect, the magnitude of which could be controlled, and calculations and GCM computations both indicate that its magnitude could be sufficient to balance the warming due to increased atmospheric carbon dioxide concentrations resulting from the burning of fossil fuels. It is proposed to increase N by atomizing seawater at the ocean surface (producing copious quantities of droplets of around 1micron in size), and the significant fraction of these which rise into the low-level clouds above would act as cloud condensation nuclei (CCN), thereby creating additional droplets and enhancing N. The seawater droplets would probably be disseminated from a fleet of satellite-controlled unmanned vessels, deriving their required energy from wind or wave-power. Control over the degree of planetary cooling could be achieved via albedo measurements linked to a global climate model.

Technological questions regarding the production and dissemination of these particles remain to be resolved. Also, detailed examination of the meteorological and climatological ramifications of this proposed geo-engineering scheme would need to be conducted before justification would exist for its operational deployment. Two advantages of the scheme are that: (1) it is relatively benign, the only raw material being seawater; (2) if the disseminators were switched off, the droplets introduced into the atmosphere would fall back into the oceans within a few days.