Social Studies March 2007

Global Warming: The Convenient Truth

Slow-but-steady is not only the easiest approach to dealing with global warming; it is also the most effective.

In October, British Prime Minister Tony Blair called for "radical international measures" to curtail greenhouse-gas emissions, and fast. "We can't wait the five years it took to negotiate Kyoto," he said. Apparently, 2012 is too late. In hopes of taking stronger steps, however, many U.S. environmentalists want to defer any legislation until President Bush is out of office. Apparently 2007 and 2008 are too early.

That gives us precisely three years—2009, 2010, and 2011—to save the planet.

All right, that was a cheap shot. I couldn't help myself. Something about the global-warming debate encourages overheated rhetoric. To listen to Blair, former Vice President Gore, and many other political figures and environmental activists, you would conclude that global warming is an onrushing cataclysm and that prevention requires all of us to take radical steps right away.

A fairer assessment would be many degrees cooler. It would hold that climate change is real and deserves action, but that the problem is nowhere near as overwhelming as the rhetoric commonly suggests, and the solutions nowhere near as difficult. As problems go, in fact, climate change appears to be one of the most convenient that humankind has ever faced.

Last month, the Intergovernmental Panel on Climate Change announced that the Earth is definitely warming and that human emissions of greenhouse gases (principally carbon dioxide) are almost certainly an important cause.

We have a problem. But what sort of problem?

A crisis, Blair says. "It is not in doubt," he said in October, "that if the science is right, the consequences for our planet are literally disastrous." He was commenting on a recent British government report (popularly known as the Stern Report) on the economic effects of warming. In The Baltimore Sun, Bryan Mignone, a science and technology fellow at the Brookings Institution, cites that report's conclusion with alarm: "The damage associated with warming under a 'do-nothing' policy is likely to be 5 percent to 20 percent of global gross domestic product, an outcome to which the word 'catastrophic' would seem to apply."

Not so fast. Other analyses come up with cost figures more like 3 percent of GDP, but leave that aside. Reanalyzing the Stern Report, Yale University economist William Nordhaus recently noted that a "high-damage" scenario might reduce global GDP by almost 14 percent in the year 2200. On the Stern Report's own assumptions, "This means that per capita consumption would grow from $7,800 today to only $81,000 in 2200," instead of $94,000 (in today's dollars). That's not good, but it hardly seems catastrophic.

The IPCC says that the world would continue to warm for decades even if all human greenhouse-gas emissions were to magically stop tomorrow, which of course they won't. In testimony last month before a House of Representatives panel, Kevin Trenberth of the National Center for Atmospheric Research, said, "The 2007 IPCC report makes clear that even aggressive mitigation would yield benefits many decades in the future, and that no amount of mitigation can avoid significant climate change."

Carbon dioxide both accumulates and dissipates in the atmosphere very slowly. Because the stock of greenhouse gases already present in the atmosphere dwarfs any one year's emissions, and because any one year's emissions can be changed only slightly, stabilizing greenhouse gases is like turning an aircraft carrier, only much slower. Annual emissions might be stabilized toward midcentury, and atmospheric concentrations at some point after that; but sharp turns are impossible and short-term effects minuscule.

That would be cause for alarm in an emergency. And many people talk as if there were one. "We need to act soon, before we reach a tipping point," Sen. Barbara Boxer, D-Calif., said at a hearing in January. Echoing Blair (as is his wont), David Cameron, the leader of Britain's Conservative Party, recently told reporters that the "big question" is, "Are we going to act before it's too late?"

Actually, there is no "too late," because there is no particular CO2 target and no particular date by which it must be met. And there is no emergency. An emergency is a "now or never" situation, but climate change is a "now versus later" situation. Immediacy trades off against efficiency.

"What we do now makes a difference for the future," says Gerald Meehl, a senior scientist at the National Center for Atmospheric Research. "The longer we wait, the worse the problem gets." On the other hand, the more precipitously we act, the more we disrupt the economy. A coal-fired electric plant lasts 40 to 60 years; gradually replacing dirty old plants with clean new ones is much more efficient than abruptly decommissioning old plants and replacing them with—well, with nothing, because electric plants take years to build. Besides, the best carbon-cutting technologies are still in development. "We know from experience the length of time it takes to develop and implement new technologies in the electricity sector," says Revis James of the Electric Power Research Institute. "That's about 20 to 25 years."

Presented by

Jonathan Rauch is a contributing editor of The Atlantic and National Journal and a senior fellow at the Brookings Institution.

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