With greenhouse gas levels increasing in the atmosphere and humans showing little collective will to control the emissions, researchers are looking more closely at potential solutions that would’ve seemed inconceivable just a few years ago.
For example: What if humans, in an effort to reflect some of the sun’s heat away from Earth, pumped aerosols into the atmosphere to form a sort of curtain over the land and oceans?
That’s essentially what happens when a big volcano erupts, but for humans to do the job, it would require engineering on an unprecedented scale. And yet, at the AAAS Annual meeting, it was clear that with climate changes growing more worrisome, geo-engineering has moved from the fringe closer to the mainstream.
In an article in ScienceNOW and in a Science Podcast interview, Eli Kintisch explored how the idea might work—and the possible impacts suggested by climate modeling.
Kintisch talked with Ken Caldeira, a geochemist at the Carnegie Institution in Stanford, California. Caldeira has used climate models to assess the impact of various aerosol-distribution patterns.
After much work, Caldeira said, the climate models have become fairly predictable. Perhaps the optimal approach would be to put concentrations of aerosols above the poles. But the models have yet to find way to cool temperatures without affecting precipitation and other factors.
“These geo-engineering approaches can make most places better most of the time, but will cause some damage to some places,” Caldeira said. “And there’s the complex problem of how do you balance that you do against the benefit that you do.”
Karin Zeitvogel, writing for Agence France-Presse, said researchers are studying the steam from ships, condensation trails of airplanes, and volcanic eruptions as they try to assess the potential of geo-engineering. But others, she said, are warning that geo-engineering is “distracting the world from reducing greenhouse gases.”
“There's a huge scope for new methods because once you realize you can make things by direct condensation from vapor, then all different sorts of compounds are possible,” said David Keith, a professor of earth sciences at the University of Calgary. “But it's much harder to figure out the environmental risks and effectiveness of these new methods unless you put them up. That is going to be a fundamental ongoing problem.”
The AFP story also quoted James Fleming, a professor of science, technology, and society at Colby College in Maine. “We need to have a little more insight,” Fleming said. “We should avoid pitfalls and not rush forward.”