Assessing the Pros and Cons of Geoengineering to Fight Climate Change
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 in Albuquerque, N.M., ecologists discussed 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,” said 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, said Jackson, who is Nicholas Professor of Global Environmental Change at the Nicholas School.
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 argued that despite its potential to create overall cooling, atmospheric seeding could cause significant changes in localized temperature and precipitation. Her simulations predict that sulfur seeding could destroy atmospheric ozone, leading to increased ultraviolet radiation reaching the Earth’s surface.
Another large-scale geoengineering scheme is fertilizing the oceans with iron to increase carbon uptake from the atmosphere. Charles Miller of Oregon State University said that ocean fertilization could create a rise in iron-limited phytoplankton populations, which by dying and sinking would use enough oxygen to create extensive dead zones in the oceans.
In addition, he said, the maximum possible rate of ocean iron fertilization could only offset a small fraction of the current rate of carbon burning by humans.
Ocean fertilization also does not alleviate the increasing problem of ocean acidification, caused by carbon dioxide from the increasingly carbon-rich atmosphere dissolving into seawater. In fact, Miller said, ocean fertilization schemes will likely exacerbate this problem.
Despite its apparent hazards at the global scale, Jackson said he thought that research should continue on safer
ways to use geoengineering at a smaller scale. But on the planetary scale, most ecologists are skeptical of climate engineering.
“Playing with the Earth’s climate is a dangerous game with unclear rules,” said Jackson. “We need more direct ways to tackle global warming, including energy efficiency, reduced consumption, and investment in renewable
energy sources.”
