Global Cooling

Cloud Seeding to Avert Catastrophic Global Warming

By John Latham

Global Cooling is an informal group of collaborating scientists from the US and UK examining an idea for creating a controlled global cooling to balance global warming resulting from burning fossil fuel. This group is organized by Dr John Latham, National Center for Atmospheric Research, Boulder, Colorado, who first published the idea, which involves seeding marine clouds to increase their reflectivity.

We propose to assess and develop a scheme for mitigating global warming by producing a controlled enhancement of the reflectivity of low lying maritime clouds for incoming sunlight by spraying into them seawater particles from a fleet of wind-powered satellite controlled unmanned vessels. These particles will create additional droplets in the clouds, thereby increasing their albedo.

The likelihood that the major countries of the world will limit their carbon dioxide emissions sufficiently to prevent disastrous consequences before carbon-free energy sources are developed to replace fossil-fuel burning are slender, and it is therefore imperative to devote resources to the examination of possible 'geoengineering' ideas for suppressing further warming, probably for several decades, until clean-energy sources are in full operation.

Latham and colleagues are examining one such idea, which involves making low level marine clouds, which cover about a third of the ocean surface, more reflective to incoming sunlight, thereby producing a cooling which could be controlled and adequate to balance global warming. This idea has been published in a number of peer-reviewed articles and has received a positive response internationally when presented at numerous conferences and research institutions.

The two scientists with significant time to devote to the pursuance of our global cooling idea are Dr John Latham, formerly Head of the Atmospheric Physics Research Group and Professor of Physics at the University of Manchester, UK (and now holding the honorary position of Senior Research Associate at the National Center for Atmospheric Research, Boulder, Colorado), and Dr Stephen Salter, Emeritus Professor of Engineering Design at the University of Edinburgh, UK. Other scientists have been extremely helpful to us but other duties have prevented them from being able to devote more than a minor fraction of their time to this work. These scientists include: Dr Tom Choularton & Dr Keith Bower (University of Manchester, UK), Dr Alan Gadian & Dr Mike Smith (University of Leeds, UK), Dr Tom Stevenson (University of Edinburgh, UK) and Dr Andy Jones (Hadley Center, Meteorological Office, UK).

Our geoengineering idea (first advanced by Latham, 1990) involves increasing the reflectivity (albedo) of the Earth to incoming sunlight. Obviously, if a greater fraction of the sunlight arriving at the top of the atmosphere is reflected back into space, the overall result is a cooling of the Earth. Our calculations (Latham, 1990, 2002; Bower et al. 2006) indicate that adequate cooling could be achieved by increasing the reflectivity of low-level shallow maritime clouds - which cover a large fraction of the oceanic surface - by atomizing sea-water beneath them to produce tiny droplets, a significant fraction of which enter the clouds, act as centers for additional droplet formation, and thus, for well-established physical reasons, cause them to become more reflective. Although it may transpire that the optimal scheme will be to modify clouds on an essentially global scale, computations (Jones et al., 2007) made using the Hadley Center's global climate model show that the scheme could produce a global cooling sufficient to balance the warming resulting from a doubling of the atmospheric carbon dioxide concentration by seeding clouds in three oceanic regions – off the west coasts of Africa and North and South America, which together cover about 10% of the Earth's surface. Plans - spearheaded by Salter (Salter and Sortino, 2007) - are well advanced for dealing with the crucial engineering problems of the production and dissemination of these seawater droplets at the rates and on the geographical scales required. Our current thinking is that these particles would be disseminated from unmanned, satellite-controlled, wind-powered vessels designed by Salter and based on an original design by Anton Flettner in the nineteen twenties.

This proposed technique has the advantages that: (1) the only raw material required is seawater; (2) the amount of global cooling could be controlled; (3) if necessary, the system could be switched off with conditions returning to normal within a few days. However, as with all geoengineering ideas, there are a number of important possible meteorological and safety ramifications which must be fully and satisfactorily examined before operational deployment of such a scheme would be justified. These include assessments, which would require major computations, using the best available global climate models, of the influence of the possible deployment of our scheme on the global wind structure and on rainfall. It may well prove advantageous that our scheme does not require fully global seeding, so that – to a significant degree – we could choose to adulterate clouds which are a long way from sensitive areas. In fact, the maximum reflectivity increase for a fixed amount of seeding is in clouds most remote from land.

We have no doubt that the ideal ultimate solution to the global warming problem would be for fossil fuel burning to be reduced by the requisite amount to halt further temperature rise, we but are convinced that such a reduction is highly unlikely to occur in the near future. If our scheme (or any other reflectivity enhancement or global cooling technique) could successfully be deployed operationally, it would not, of course, affect the atmospheric carbon dioxide levels, whose increase has injurious planetary effects which will need to be addressed, in addition to temperature enhancement. However, if it proved feasible, in a controlled way, to produce a cooling to compensate for global warming, we could buy time within which to stave off catastrophic warming while clean energy sources which could take over from fossil fuel burning are being developed (Latham, 2007). We are very encouraged by the positive reactions to our scheme from climate scientists. We regard it as deplorable that resources have so far not been provided to enable any such ideas to be adequately assessed.

Our global cooling scheme has been favorably received and we have published four papers on it. We are currently actively seeking funding on a non-profit basis under the auspices of Global Cooling. For more information please see the info below and email John Latham.

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Global Cooling
601 East Street
Gold Hill
Boulder
Colorado 80302-9771

Tel: 303-497-8182 & 303-444-2429 (John Latham)
Fax: 303-497-8181 & 303-444-2429

The six papers emanating from our work to date are:

1. Latham,J., 1990: Control of global warming? Nature 347. 339-340.

2. Latham, J., 2002, Amelioration of Global Warming by Controlled Enhancement of the Albedo and Longevity of Low-Level Maritime Clouds. Atmos. Sci. Letters.
(doi:10.1006/Asle.2002.0048)

3. K.Bower, T.W.Choularton, J.Latham, J.Sahraei and S.Salter., 2006. Computational assessment of a proposed technique for Global warming Mitigation via albedo-enhancement of marine stratocumulus clouds. Atmos. Res. 82, 328-336.

4. A.Jones, J.Latham and M.H.Smith, 2007. Radiative Forcing due to Modification of Marine Stratocumulus Clouds. (currently unpublished).

5. S.Salter and G.N.Sortino, 2007. Sea-going Hardware for the Implementation of the Cloud Albedo Control Method for the Reduction of Global Warming. (currently unpublished).

6. J. Latham, 2007. Cooling may be possible, but we need safety Data. Nature, 447, 908.

Global Cooling is a fiscally sponsored non-profit project of Planetwork NGO, Inc. a CA 501(c)3.
All donations are fully tax deductible to the full extent allowable by law.