Scientists call for research on geoengineering scheme to block sunlight

Jeremy Hance
January 27, 2010

The idea goes something like this: nations would send megatons of light-scattering aerosol particles into the globe's upper atmosphere, significantly reducing sunlight reaching the earth and thereby immediately cooling the Earth. While the idea may sound like science-fiction—or desperate, depending on your opinion—researchers writing in Science say that it may be one of the best ways to lower the Earth's temperature. They argue that international research and field testing of the idea, known as solar-radiation management (SRM), should begin immediately.

"Solar-radiation management may be the only human response that can fend off rapid and high-consequence climate change impacts. The risks of not doing research outweigh the risks of doing it," says co-author David Keith, director of the Institute for Sustainable Energy, Environment and Economy's energy and environmental systems group and a professor in the Schulich School of Engineering.

The researchers fear that if international research does not start soon, nations may begin researching and testing the idea unilaterally, thereby increasing the risk that down the road a rogue nation will begin SRM without the consent of others.

In the opinion-piece, the scientists say that an international research budget of 10 million should begin now and grow to 1 billion by 2020.

However, the authors add that SRM technology should not be considered a cure-all: nations would still need to make big cuts in their greenhouse gas emissions to avoid climate disaster.

"We must develop the capability to do SRM in a manner that complements such cuts, while managing the associated environmental and political risks," the authors write, adding that, "the two are not in opposition. We are currently doing neither; action is urgently needed on both."

One clear benefit of SRM is that it would begin cooling of the Earth immediately, whereas large cuts in greenhouse gas emissions will take many decades before the climate responds, since time is required for CO2 already in the atmosphere to break down.

While SRM is seen by many as the 'safest' and cheapest of the geoengineering proposals to date, there are risks, including a decrease in precipitation and evaporation. In addition, the effects of SRM would likely not occur consistently over the whole planet.

"If the world relies solely on SRM to limit (global) warming, these problems will eventually pose risks as large as those from uncontrolled emissions," the researchers write.

The writers say that only further research and small-scale tests would allow scientists to understand the risks and benefits of SRM more fully.

"If SRM proves to be unworkable or poses unacceptable risks, the sooner we know the less moral hazard it poses; if it is effective, we gain a useful additional tool to limit climate damages," they write.

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Jeremy Hance
mongabay.com (January 27, 2010).

Scientists call for research on geoengineering scheme to block sunlight.