Geoengineering

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19 November 2010

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Geo-engineers Suggest

Ways of Countering Climate Change

Scientists are thinking up massive projects

to give time to cut carbon emissions

Carol Bean

How about lobbing giant lenses into orbit with thousand-kilometre diameters to reflect back some of the Sun’s heat? That idea came from James Early of the Lawrence Livermore National Laboratory in California.

Another version is to send up clouds of tiny, wafer-thin, lenses. Thanks to Roger Angel at the University of Arizona for this. Both these schemes would be placed 1.5 million kilometres above Earth.

As can be expected they have price tags in the trillions of dollars and are, so far, beyond the ability of our space technology.

A bit closer to Earth is a concept from Professor Gregory Benford, at the University of California. He thinks 24 kilometres might be high enough. Dr. Benford suggests sprinkling tiny, harmless particles of silicon dioxide into the stratosphere. The particles would eventually fall to the ground and have to be replaced, but this plan is doable today.

Still with the shield proposals, there’s one suggestion to use wind-powered ships to vapourize sea water and create clouds. There’s nothing new about this; a German engineer named Anton Flettner designed and built such a vessel (at left), which sailed across the Atlantic in 1926.

Professor Stephen Salter, from Edinburgh University’s School of Engineering is updating Flettner’s plan by adding the cloud-forming component.

“Flettner” ships would generate electricity from turbines pulled behind them. The electrical power would be used to spray fine droplets of seawater into the air, creating low-hanging clouds to reflect sunlight. He is suggesting deploying a fleet of these “cloudseeding” ships.

Some scientists have suggested fertilizing the oceans with iron. At least one company, Climos, of San Francisco is already working on the notion. The iron would create huge blooms of plankton that would then consume tonnes of carbon dioxide and, as the plants died, drag the carbon down to the seabed.

Professor James Lovelock who developed the Gaia hypothesis is working on an idea aimed at cooling the oceans. Along with Professor Chris Rapley of London’s Science Museum, he envisages a series of 100-metre-long tubes anchored vertically under water. These tubes would draw cold water from lower depths and bring it up to mix with warmer surface water.

As Sanjida O’Connell described the plan in the February 17, 2009 issue of The Telegraph (U.K.) “Cooler oceans mean a cooler planet, while the nutrient-rich water brought up from the bottom could encourage algal blooms, which use carbon to grow and thereby remove it from the atmosphere.”

Creating artificial volcanoes to release sulphur into the atmosphere is also being worked on. This is just copying Nature say its supporters.

In 1991, Mount Pinatubo in the Philippines blew its top. So much dust and sulphur was released that there was a measurable downward trend in temperatures around the globe. Others have put forward a plan to cover the world’s deserts with reflective film that would bounce some of the Sun’s heat back into space.

No one solution will solve the global warming problem. Dramatically cutting carbon emissions is the only permanent solution, but some of these clever ideas might buy us some time in which to get that done.