SciTech

Blocking the sun may reduce global warming

Geoengineering, the science of intentionally altering the Earth’s climate to combat environmental hazards, is being considered by some researchers as a viable method to reduce global warming. Particles would be released into the atmosphere to block some of the sun. (credit: Jessica Thurston/Contributing Editor and Maria Raffaele/Art Editor ) Geoengineering, the science of intentionally altering the Earth’s climate to combat environmental hazards, is being considered by some researchers as a viable method to reduce global warming. Particles would be released into the atmosphere to block some of the sun. (credit: Jessica Thurston/Contributing Editor and Maria Raffaele/Art Editor )

Experts may agree that reducing carbon dioxide emissions is the best solution to solving the problem of global warming, but an engineer at Carnegie Mellon has created a new alternative. Called geoengineering, it is the science of intentionally altering the Earth’s climate to combat environmental hazards.

Granger Morgan, the head of the department of engineering and public policy in the Carnegie Institute of Technology, said that geoengineering is “always in the shadows or on the back burner” when it comes to addressing environmental issues. Alongside David W. Keith of the University of Calgary in Alberta and Edward Parson of the University of Michigan, Morgan aims to teach the public about the possibilities of geoengineering.

Geoengineering has been around since the briefing of President Lyndon Johnson on climate change in the 1960s. Ever since that introduction about environmental danger, the international community has made slow progress in changing carbon dioxide levels. At first, people worried about the use of the technology for ill intentions. But 40 years later, ill intention has become the least of the problems.

Morgan’s particular type of geoengineering, known as solar radiation management (SRM), involves putting fine particles into the atmosphere, much like the smoke that enters the atmosphere after a volcano erupts. One of the suggested fine particles, sulfur dioxide, is actually a component of volcanic ash. These particles are effective at reflecting sunlight, thereby reducing the amount of sunlight that passes through the atmosphere. According to an opinion article Morgan wrote for the scientific journal Nature, the method’s relatively low cost (when compared to the larger cost of emission cuts) and the speed (it can reduce global temperatures in the time span of only a few months) are also big benefits.

Besides the gradual rise of average temperatures worldwide, carbon dioxide levels have led to the acidification of the ocean to levels 30 percent higher than during pre-industrial times. “By the end of this century,” Morgan predicts, “we might lose most of our coral reefs as the ocean becomes too acidic to lay down deposits.”

If SRM is an option taken in the future, Morgan advises seeking multilateral action with countries all over the world. Without strong relations between countries regarding SRM, nations would disagree on when to use the SRM option versus when to focus on reducing emissions. There is currently no treaty regarding geoengineering practices, so, according to Morgan’s article in Nature, “immediate negotiation of a treaty is probably not advisable.”

Instead, Morgan and his team suggest strong links be formed between researchers, government officials, and policy makers. The first step would be conducting research and making risk assessments on the technology by independent teams, while experts and world leaders could discuss possible implications in risk, acceptability, and regulation.

Morgan dispels any question about potential health hazards of SRM. Although sulfur dioxide has been proven to cause acid rain, for example, the small quantity that would be placed into the atmosphere would cause little change to current amounts of acid rain, he said.

One of the largest problems with this process today is the risk of dependency on solar radiation management. Geoengineering, Morgan emphasized, only reduces the amount of sunlight that passes through the atmosphere, but does nothing for reducing carbon dioxide emissions. He compared the life of a carbon dioxide molecule to “a bathtub with a large faucet and a small drain.” Carbon dioxide breaks down much more slowly than it accumulates.

Dependency yields other unpleasant side effects as well. The sheer price of continuously placing fine particles into the atmosphere is enough of a deterrent. Side effects of the particles are a net cooling of temperatures, less precipitation, less evaporation, and the protection of some areas of the world more than others. The carbon dioxide levels would continue to rise, and once this temporary solution could not be supported any longer, the heating of the earth due to the built-up carbon dioxide would be even greater.

In order to analyze these issues and many others, reports British newspaper The Guardian, scientists will host a summit in California in March.