Cloud Whitening: "Bill Gates Pays for ‘Artificial’ Clouds to Beat Greenhouse Gases
Cloud reflectivity enhancement is also known as 'marine cloud brightening' or 'cloud whitening' on low cloud. An opposite scheme exists to reduce the reflectivity of higher, colder cirrus clouds. It is a geoengineering technique that works by solar radiation management. By modifying the reflectivity of clouds, the albedo of the Earth is altered. The intention is that this technique, in combination with greenhouse gas emissions reduction (and possibly other geoengineering techniques) will be sufficient to control global warming. Compared to other climate modification strategies, this technique is relatively simple and benign, being based as it is on natural processes of 'ocean spray'. It can therefore be deployed quickly for further research, and can then be rolled out on an effective scale relatively cheaply after that. The effect is expected to be fully reversible, as the cloud condensation nuclei particles precipitate naturally. However, like any planetary-scale project dealing with the complex climate system, there is a non-trivial risk of unintended consequences.
The U.K. Sunday Times (5-8-10) reports:
The first trials of controversial sunshielding technology are being planned after the United Nations failed to secure agreement on cutting greenhouse gases.
Bill Gates, the Microsoft billionaire, is funding research into machines to suck up ten tonnes of seawater every second and spray it upwards. This would seed vast banks of white clouds to reflect the Sun’s rays away from Earth.
...a study last year calculated that a fleet of 1,900 ships costing £5 billion could arrest the rise in temperature by criss-crossing the oceans and spraying seawater from tall funnels to whiten clouds and increase their reflectivity.
Silver Lining [here], a research body in San Francisco, has received $300,000 (£204,000) from Mr Gates. It will develop machines to convert seawater into microscopic particles capable of being blown up to the cloud level of 1,000 metres. This would whiten clouds by increasing the number of nuclei.
The trial would involve ten ships and 10,000sq km (3,800sq miles) of ocean. Armand Neukermanns, who is leading the research, said that whitening clouds was “the most benign form of engineering” because, while it might alter rainfall, the effects would cease soon after the machines were switched off...
Stephen Salter, Emeritus Professor of Engineering Design at the University of Edinburgh, said that there was no need to wait for regulations because the trials would not add chemicals to the atmosphere. But Sir David King, former chief scientific adviser to the Government, said that experiments with potential consequences beyond national borders needed international regulations. He told The Times: “I do not see any geoengineering solution which does not have unintended consequences or is not far too expensive.”
Cloud Whitening sounds like a really great idea, but Mike Hulme a professor of climate change in the School of Environmental Sciences at the University of East Anglia explains some of the difficulties that may arise when mankind attempts to geoengineer the climate in Yale Environment 360 (6-7-10):
[C]arrying out geoengineering plans could prove daunting, as conflicts erupt over the unintended regional consequences of climate intervention and over who is entitled to deploy climate-altering technologies...
How do we judge the risks of unintended consequences? And who is entitled to initiate the large-scale deployment of a climate intervention technology — and under what circumstances?
Proponents are suggesting two broad categories of technologies to roll back global warming. The first, solar radiation management (SRM), calls for altering the solar radiation budget of the planet, using such technologies as mirrors in space, aerosols in the stratosphere, and cloud whitening over the oceans. And then there are technologies, grouped under the category of carbon dioxide removal (CDR), that propose to accelerate the removal of carbon dioxide from the atmosphere by fertilizing the oceans with iron, extracting CO2 from the atmosphere, or sequestering CO2 by heating biomass in oxygen-free kilns and burying the charcoal underground.
Such interventions would bring about, if not exactly artificial climates, then certainly synthetic ones...
[C]limate intervention technologies raise serious ethical questions about the propriety of such manipulations, about their accordance with the collective will of people on Earth, and about the unforeseen side effects of such interventions. But the proposition of creating synthetic climates through solar radiation management (less so with carbon dioxide removal) introduces a range of additional concerns not shared with microscopic cellular manipulation. These concerns arise from the brute fact that there is only one climate system with which to experiment, and it is the one we live with. If it is planetary-scale manipulation of climate that is desired — and it is — then experimentation has to be conducted on a planetary scale to prove the effectiveness — or not — of the technology.
The first concern is the risk of unintended consequences. Given that it is not possible to conduct large-scale planetary experiments in solar radiation management before going “live” with the technology, risk assessments have to fall back on using virtual climates generated by computer models. The Earth system models currently used to explore the possible future effects of rising atmospheric concentrations of greenhouse gases are the same ones that have to be used to explore the simulated consequences of a variety of solar radiation interventions.
Using aerosols to offset the additional planetary heating caused by greenhouse gases is a relatively straightforward theoretical calculation; it is a case of simple planetary budgeting. Much harder is to know what this “re-balancing” of the global heat budget will do to atmospheric and ocean dynamics around the world. These are the dynamics that make weather happen at particular times and in particular places and which — through various combinations of rain, wind, temperature, and humidity — shape ecological processes and human social practices. The dangers and opportunities associated with climate occur through these local weather phenomena, not through an abstract index of global temperature.
If the goal of climate engineering is simply to reset the global temperature dial at its 19th or late-20th century register, that might be possible to do. But in the process of doing so, significant perturbations to regional climate conditions, and inter-annual variability around those conditions, are likely to be introduced. Even if changes in the frequency and intensity of storms and precipitation were to be a zero-sum game globally, the distributional effects of such changes will create winners and losers. [Read all of this thoughtful article.]