How to Fix a Climate Emergency

Now, however, many scientists are starting to take geo-engineering seriously, if only out of desperation. As more and more climate specialists come to believe that even current levels of carbon pollution are warming the globe more rapidly than previously thought, the case for developing an emergency earth-rescue plan is getting difficult to resist. Nobel laureates Paul Crutzen and Thomas Schelling have endorsed the need for a climate-engineering plan. The British Royal Society has begun to study the options. The U.S. National Academies of Science just convened a conference in which climate engineering was discussed, and it's scheduled a meeting in June to hammer out details. "It still hasn't shown up on politicians' agendas," says Princeton climate scientist Michael Oppenheimer, "but scientists are now talking about it as an option."

Oppenheimer is working on a team that will produce a National Academies of Science report recommending a geo-engineering option in climate policy. Oppenheimer is on the cautious side, supporting theoretical research only, with no field experiments that might have a lasting impact on the environment. Other scientists, however, are beginning to press the issue. "A lot of people don't like the idea of solving our problems with technology," says Harvard climatologist Dan Schrag. "If you're sitting in an ivory tower, it's easy to say we have to all change our behavior. But what if we don't? Do you really want to kiss the earth goodbye?"

The most eloquent argument for geo-engineering as a Plan B is the failure of Plan A—emissions cuts. The Kyoto agreement calls for a 5.2 percent reduction of emissions below 1990s levels by 2012. Of the 40 countries that signed the agreement in 2001, 21 have seen carbon emissions increase since then. That includes Japan, which hosted the talks. Although Britain, Germany and France have managed to make reductions, none is currently on track to meet its Kyoto target. And Kyoto didn't include China or the United States, the world's No. 1 and 2 carbon emitters.

The campaign to expand and tighten Kyoto now looks likely to fall short, too. In December, negotiators will gather in Copenhagen and attempt to extend the Kyoto agreement, which expires in 2012. They also hope to impose more demanding cuts in emissions, and to bring China and the U.S. onboard. The hope is that Copenhagen will cap the amount of carbon in the atmosphere at a level low enough to prevent temperatures from rising more than 2 degrees Celsius. If temperatures go higher, many climate scientists worry that the effects will exact an unacceptable toll on the environment, exacerbating drought and flooding, endangering coastal areas from sea-level rise, hurting agriculture and leading to loss of biodiversity. No one is certain how sharp the cuts in greenhouse-gas emissions need to be, but the best guess is a reduction of 80 percent below current levels by 2050. That's a radical goal for Europe, Japan and the United States. For China and India, which are trying to grow their way out of poverty, it's almost unthinkable.

The glacial pace of global politics may be no match for the pace of climate change. Just because the earth's climate system is a big, slow-moving machine with lots of inertia, it doesn't mean a catastrophe would also be slow in coming. One of the increasingly frightening scenarios is a snowball effect, in which, for example, carbon begins to seep out of melting permafrost, or warming oceans raise atmospheric humidity, amplifying the greenhouse effect of carbon. Perhaps most important is the growing consensus that the gas we've already emitted will go on warming the earth for centuries. The landmark 2007 report from the U.N.'s Intergovernmental Panel on Climate Change estimated that by the end of the century, temperatures could rise by between 2 and 5 degrees Celsius. An increasing number of scientists are coming to believe in the worst-case scenario. A 5-degree spike by 2100— a brief instant in geologic time—would almost certainly prove to be a disaster for civilization. That's why many scientists have begun to urge serious consideration to geo-engineering schemes that only a few years ago seemed absurd and dangerous.

The irony is that the more respectable geo-engineering option, carbon capture, is also by far the more expensive and less likely to counteract a steep rise in temperatures. It's easy to see why the idea of cleaning the air is far less controversial than the idea of cooling it—because cleaning involves no massive release of new gases or hardware, and thus far less risk that the experiment will run out of control. Columbia University climate scientists Wallace Broecker and Klaus Lackner have argued that the same technology used for capturing the carbon in coal plants could be trained on the atmosphere at large. But the task of vacuuming up this much carbon would be mind-bogglingly huge. Each year roughly 30 billion metric tons of carbon dioxide are released by the world's industries and autos. If converted to liquid form, it would take less than four years to fill an underground space with the volume of Lake Geneva.

And that doesn't take into account the 1.8 percent yearly rise in emissions, or the billions of tons of carbon dioxide that have already accumulated in the atmosphere for the past 100 years (there's no reliable estimate of how much that is). Scientists still think there's enough porous rock deep beneath the earth's surface to accommodate all the liquid carbon dioxide we can pump, but getting it there would take many years and cost billions. Assuming the cost of removing carbon eventually falls to $50 a ton (it now costs $200 per ton), the bill for removing only the current year's emissions would reach $150 billion.