The Science of Sustainability

Engineering the Planet

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On the surface, geoengineering almost seems like science fiction. Could humans engineer a way to compensate for global warming by changing dynamics in the Earth's atmosphere? But it's one of the ideas being discussing at the American Geophysical Union conference in San Francisco. Each year, thousands of scientists descend on downtown San Francisco to hold a week of meetings and discussions.

Here's how the idea would work: Using planes or other high-altitude transport, we'd disburse millions of tons of sulfur dioxide (or hydrogen sulfide) into the stratosphere, 13 miles above the Earth. Those gases would create tiny particles, which would reflect sunlight. This process already goes on in the stratosphere – about a third of the energy from the sun is reflected back into space thanks to this dynamic. But by adding more reflecting particles, scientists think it might be possible to cool the planet – and compensate for human-induced warming.

No one has tried this idea yet – but it's something scientists have already observed — through volcanoes. In 1991, Mount Pinatubo erupted in the Philippines, spewing 20 million tons of sulfur dioxide into the atmosphere. As a result, global temperatures temporarily dropped about one degree Fahrenheit.

That doesn't necessarily mean a scheme like this would work. As UCLA Scientist Richard Turco said, it's not easy to predict how the particles would react and disburse. "If the particles are too large, that would actually create a warming effect, a greenhouse warming. Small particles are not useful because they don't reflect much radiation."

This plan isn't just a one time deal. As Turco continued, "we would need a huge monitoring system and can't afford to make any mistakes. Once you start this process, you have to maintain it for two to three centuries."

And then there's the "get out of jail free" aspect. If the focus of climate change policy becomes geoengineering, what happens to simply cutting emissions? As Professor Alan Robock of Rutgers University acknowledged, the costs and technology of geoengineering are uncertain — and it wouldn't curb other climate change impacts, like ocean acidification. "We have to focus on mitigation and keep this in our back pocket for emergencies."

According to Professor David Keith of the University of Calagry, it's worth studying geoengineering — just in case. Our greenhouse gas emissions will continue to grow. "We're not going to stop today, and even if we stopped today, there's enormous inertia," Keith said. In the event that climate change becomes catastrophic, Keith says we may need a last resort. "Whether you like or don't like this, it can be done quickly."

For more on what's new at the AGU, check out KQED's Climate Watch blog.

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Category: Climate, Environment

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About the Author ()

Lauren is a radio reporter covering environment, water, and energy for KQED Science. As part of her day job, she has scaled Sierra Nevada peaks, run from charging elephant seals, and desperately tried to get her sea legs - all in pursuit of good radio. Her work has appeared on Marketplace, Living on Earth, and NPR's Morning Edition and All Things Considered. You can find her on Twitter at @lesommer.