Symposium to discuss geoengineering to fight climate change at the ESA Annu...( Geoengineering techniques aim to slo...)

Geoengineering techniques aim to slow global warming through the use of human-made changes to the Earth's land, seas or atmosphere. But new research shows that the use of geoengineering to do environmental good may cause other environmental harm. In a symposium at the Ecological Society of America's Annual Meeting, ecologists discuss the viability of geoengineering, concluding that it is potentially dangerous at the global scale, where the risks outweigh the benefits.

"The bigger the scale of the approach, the riskier it is for the environment," says session organizer Robert Jackson , director of Duke University's Center on Global Change. Global alterations of Earth's natural cycles have too many uncertainties to be viable with our current level of understanding, he says.

One global-scale geoengineering method, termed atmospheric seeding, would cool the climate by releasing light-colored sulfur particles or other aerosols into the atmosphere to reflect the sun's rays back into space. This approach mimics what happens naturally when volcanoes erupt; in 1991, for instance, an eruption of Mount Pinatubo in the Philippines cooled the Earth by 0.9 degrees Fahrenheit.

But Simone Tilmes of the National Center for Atmospheric Research argues that despite its potential to create overall cooling, atmospheric seeding could cause significant changes in localized temperature and precipitation. Her simulations also predict that sulfur seeding could destroy atmospheric ozone, leading to increased ultraviolet radiation reaching the Earth's surface.

"An increase in ozone depletion over the Arctic could lead to dangerous levels of ultraviolet light hitting the Earth's surface," she says. "In this case, the recovery of the ozone hole over the Antarctic could be delayed by decades."

Another large-scale geoengineering scheme is fertilizing the oceans with iron to increase carbon uptake from the atmosphere. Charles Miller of Oregon Stat
'/>"/>