Scientists weigh risks of climate 'techno-fixes'

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

from the March 29, 2007 edition

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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 worldchanging.com. "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."

History seems to support Mr. McKibben's critique. The Clean Air and Clean Water Acts of the 1960s and 1970s, which cost more than the estimates for curbing emissions today, are seen in retrospect as absolutely the right thing to have done. That such costs are now viewed as untenable speaks to the shortcomings of the cost-benefit approach that has driven environmental policy for the past 25 years, says Frank Ackerman, director of research and policy program at the Global Development and Environment Institute at Tufts University in Medford, Mass.

Simply put, economic analyses can't deal with far-reaching, long-term problems like climate change or geoengineering, he says. There are too many unknowns. "Changing the earth's climate is an experiment we're going to do once," he says. "There are not going to be any do-overs."

For this reason, many call global warming a moral issue, not an economic one. There are certain relationships that cannot be assigned numerical values. "If you just looked at it from a cost-benefit point of view, Central Park is completely irrational," says Dale Jamieson, director of environmental studies at New York University. "Yet, nobody would think that the fact you can sell Central Park to Donald Trump is reason to do it."

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