From: Andy Soos, ENN
Published July 27, 2012 11:49 AM

Aerosols Effect on Ozone and Global Cooling

What happens when one injects sulfate particles or aerosols into the atmosphere? Will it cause cooling (as seen with naturally occurring volcanic eruptions or will it cause harm to the ozone or other atmospheric variables? No one really knows for sure. Anderson, a professor at Harvard of atmospheric chemistry, said that he has a proposed project idea to spray a small amount of chemicals into the air to test their effect on free radicals that could destroy ozone. That’s because the aerosols may increase the reactive surface area for the conversion of chlorine (present from the release of now-banned chlorofluorocarbons) to a form that destroys ozone. The question is, how much ozone would be lost, and what benefit would be gained in the process?

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An aerosol is a suspension of fine solid particles or liquid droplets in a gas. Aerosols may do many things to the climate and the atmosphere. One is simple visibility can be affected. In terms of the climate aerosols can influence cloud formation, rainfall, smog, and atmospheric reactions.

Volcanic eruptions send vast amounts of aerosols into he atmosphere and have been observed as causing changes in precipitation, visibility (sunsets are more vivid for example) and general earth cooling.

"Our primary purpose is to protect the stratosphere by developing methods that will clearly demonstrate what the response of the stratospheric system is, without affecting the ozone," Anderson said.

"I’m extremely worried that the entire idea of putting sulfate into the stratosphere is dead on arrival, because the result of putting it in the ozone will be intolerable,” Anderson said. “If we see what we believe we will see, it will eliminate the possibility of people doing this."

In order to properly test the chemicals’ effect, the experiment does have to transpire in the open air, rather than in a laboratory, Anderson said.

"All we have to do is add minute amounts of those chemicals and look at the species that would attack ozone," Anderson said. "You don’t need to destroy any ozone. You just need to do a microscopic amount and see the immediate response of the system."

The scientific community, however, is beginning to consider outdoor tests of geoengineering schemes "with careful experiments where you really ask nature questions," Keith, a physicist and leading geoengineering researcher, said.

A controlled field experiment, he added, would help the researchers better understand the risks and benefits and thus help policy makers decide if the technologies should be pursued.

"If we knew precisely how much ozone loss there was as a function of water vapor and sulfate and chlorine, there would be no reason to do the experiment,” Keith said. “The point is we don’t."

It may one day be possible to geoengineer the planet but in order to do so we must understand what we are doing.

See the following for further information: Harvard Report and Volcanic Cooling.

Volcano image via Wikipedia.

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