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Scientists weigh risks of climate 'techno-fixes'

Schemes from space mirrors to vast algal blooms have sparked debate over the ethics of geoengineering.

By Moises Velasquez-ManoffCorrespondent of The Christian Science Monitor / March 29, 2007

Faced with the specter of a warming planet and frustrated by the lack of progress on this time-sensitive issue, some scientists have begun researching backup plans. They seek a way to give humanity direct control over Earth's thermostat.

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Proposals run the gamut from space mirrors deflecting a portion of the sun's energy to promoting vast marine algal blooms to suck carbon out of the atmosphere. The schemes have sparked a debate over the ethics of climate manipulation, especially when the uncertainties are vast and the stakes so high. For many scientists, the technology is less an issue than the decisionmaking process that may lead to its implementation.

Environmental policy driven purely by cost-benefit analyses cannot, they say, effectively point the way on large issues like climate change. But even as many scientists caution against unintended, even catastrophic consequences of tinkering with climate, they concede that the more tools humankind has to confront a serious problem, the better.

Others wonder if the mere hint of a quick-fix solution will only provide a false sense of security and hamper efforts to address the root problem: carbon emissions from a fossil fuel-based economy. And then there's the trillion-dollar question: In a politically fractured world, how will technologies that affect everyone be implemented by the few, the rich, and the tech-savvy?

When scientists talk about geoengineering, they generally mean subtracting a fraction of the sun's energy from the earth equal to that trapped by human-emitted greenhouse gases. It is not a new idea, but only recently has it moved toward the scientific mainstream. In 2006, Nobel Laureate Paul Crutzen of the Max Planck Institute for Chemistry in Mainz, Germany, published a paper on injecting particles into the upper atmosphere to reflect incoming sunlight and cool the earth. Climate scientists have since run scenarios on climate models and first reports found that it might work. In November last year, NASA cohosted a conference on the topic.

It takes only a cursory look at this century's forecast to see the utility of a climate control switch. Currently at 380 parts per million, carbon-dioxide emissions are predicted to double their preindustrial rates, to about 500 ppm, by 2100. Last time there was that much CO2 in the air, palm trees grew in Antarctica and crocodiles sloshed about in the swamps of a tepid Greenland.

The Intergovernmental Panel on Climate Change predicts a temperature increase of 5.4 degrees F. by century's end. It also predicts that, assuming continued emissions, heat stored in the ocean will continue to warm the planet for a thousand years. This last point – that even if we stop all greenhouse-gas emissions tomorrow we're in for a certain amount of warming – is reason enough to look into geoengineering, says Jamais Cascio, a futurist and cofounder of the website "If you find yourself in a hole, the first step is to stop digging," he says. "But stopping digging isn't going to get you out of your hole."

By some estimates, geoengineering has the added allure of being cheaper than curbing emissions. Economists say that decarbonizing the economy will cost around 2 percent of the gross domestic product; putting reflective aerosols into the upper atmosphere will cost about one-thousandth of that, says Ken Caldeira, a climate scientist at the Carnegie Institution at Stanford University.

But others say the discussion over mitigation seems to have gotten ahead of itself. Why talk about fixing symptoms when we have the technology to address the root cause? "There's no getting around the fact that we're in a very desperate situation," says Bill McKibben, author of "The End of Nature" and more recently "Deep Economy." But "before geoengineering, let's do a little policy engineering first."