(note: The Climate Change Conference of 2006 was held on May 10 - 12, 2006 in Ottawa, Ontario, Canada. One of the abstracts is featured in this excerpt)
(view Abstracts as HTML)
Global Warming Mitigation via Controlled Cloud Albedo Enhancement: Physical & Meteorological Aspects
Keith Bower/Tom Choularton/Dennis Cooper/Martin Gallagher/John Latham,University of Manchester,UK
Stephen Salter/Tom Stephenson,University of Edinburgh, UK
Mike Smith,University of Leeds, UK
Low-level marine stratocumulus clouds cover about 30% of the oceanic surface and characteristically possess albedos, A, (reflectivities for incoming sunlight) in the range 0.3 to 0.7.
They therefore make a significant (cooling) contribution to the radiative balance of the Earth.
[John] Latham (1990, 2002) proposed a possible technique for ameliorating global warming by means of controlled enhancement of the droplet concentrations N in such clouds, with a corresponding increase ΔA in their albedo (and also possibly in their longevity), thereby producing a cooling effect.
The technique involves dissemination - at or close to the ocean surface - of seawater (NaCl) droplets around one micrometre in size, which are sufficiently large to act as cloud condensation nuclei (CCN) when they rise into the bases of these clouds. (image at right is of Atlantic Ocean Surface Winds from NASA/QuikScat) (space.about.com)
The central physics of this scheme, which have been authoritatively treated in earlier studies, is that an increase in droplet concentration N causes the cloud albedo to increase because the overall droplet surface area is enhanced; and can increase cloud longevity (tantamount to increasing cloudiness) because the growth of cloud droplets by coalescence to form drizzle or raindrops - which often initiates cloud dissipation - is slowed down, since the droplets are smaller and the clouds correspondingly more stable.
Calculations by earlier workers indicate that a 50-100% increase in N, in marine stratocumulus clouds, on a global basis, would be sufficient to produce a cooling which would more than compensate for the warming associated with a doubling of the carbon dioxide concentration.