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Sprayed Aerosols Could Ease Climate Woes Irene Klotz, Discovery News

 

 

Dec. 29, 2008

It won't solve global warming, but a group of scientists are calling for a focused research program to investigate ways to seed the atmosphere with chemicals that would let the heat out -- literally.

Geoengineering is not a new concept. Governments have changed how and where water flows, filled in lakes and other wetlands for construction, even attempted to control the weather. A project to counter climate change, however, would take geoengineering to an entirely new level.

Leaving aside what may be insurmountable political, cultural and ethical issues, scientists meeting at the American Geophysical Conference in San Francisco earlier this month focused on the practical aspects of releasing gases into the stratosphere that could open Earth's greenhouse.

Scientists are concerned that Earth is growing increasingly warm due to "greenhouse gases," such as carbon dioxide, in the atmosphere that inhibit the planet's ability to radiation heat into space.

Human-related activities, such as burning fossil fuels, are believed to be accelerating the planet's accumulation of greenhouse gases, even though naturally occurring phenomena such as volcanic eruptions and fires account for 97 percent of carbon dioxide in the atmosphere.

"Even if we stopped emissions instantly today...we still have enough CO2 in the atmosphere that it is possible we would have unacceptable levels of climate risk," said David Keith, with the University of Calgary's Energy and Environmental Systems Group.

"While we may be lucky and find climate only warms by a degree or so, we may be unlucky and find it's more like five or six (degrees)," he added. "We're not going to know until we've put enough CO2 to make an irreversible decision.

Keith and colleagues want to investigate putting aerosols, such as sulfur, into the atmosphere to chemically unlock the greenhouse effect and allow more of the sun's reflected heat to radiate back into space.

"This brings up the question of who would make that decision," said Alan Robock of Rutgers University. And what temperature the world should be.

"A ski slope operator and someone running a shipping company in the Arctic might have different opinions about what's the ideal temperature for the planet," NASA's administrator Michael Griffin told Discovery News in an interview last year.

From an engineering standpoint, scientists have looked at a variety of systems to deliver the goods, including high-altitude aircraft, such the military's KC135 tankers used to refuel fighter jets, balloons, artillery, even a space elevator.

Other options include lacing commercial airlines' jet fuel with sulfur-containing particles, though this likely would give rise to a host of new problems, including engine contamination and safety concerns.

"No one has actually looked at what would happen if you tried to put these materials into the stratosphere," said Richard Turco, with the Department of Atmospheric and Oceanic Sciences at the University of California in Los Angeles.

Scientists disagreed on whether atmospheric seeding to change the climate could be successful on a regional level, or if any initiatives must be globally based to be effective. They were united, however, in calling for a focused research effort.

"There's very little funded research (about) managing the risks of climate change," Keith said.