The Copenhagen, Denmark, climate negotiations were only hours old when the United States faced its first demands. The Swedish Environment Minister announced that he expected President Obama to arrive in Denmark with a new promise of emissions cuts—significantly deeper than the ones now proposed. The lead Chinese negotiator, singling out the United States, reiterated his call for dramatic action from developed countries—a decrease in emissions, over the next 10 years, to at least 25 percent below 1990 levels.
They're wasting their time. The United States has already offered to cut its emissions by 17 percent from 2005 levels (which translates to about 4 percent below 1990 levels). Any promise of significantly bigger near-term cuts could alienate Congress. And despite all the invocations of science, ratcheting down the U.S. goal would make hardly any difference for the planet. Indeed, in the long term, it could backfire.
Let's check the math. Climate change occurs as greenhouse gases accumulate and stop heat from escaping into space. The atmosphere now contains about 385 parts per million of carbon dioxide; most negotiators want to keep that number at or below 450 ppm. But given the policies that countries have in place today, the world is on course to blast past 1,000 ppm. If environmental salvation really depends on a strengthened U.S. target, then one would imagine that meeting demands of a 25 percent cut from 1990 levels by 2020 would make a massive difference.
Simple arithmetic shows otherwise. Greenhouse-gas concentrations are determined by the way emissions accumulate over time. The Waxman-Markey cap-and-trade legislation passed by the U.S. House of Representatives, which the Obama administration has used as its blueprint in Copenhagen, charts out a detailed course for U.S. emissions through 2050. In the coming decade, emissions would drop to 20 percent below 2005 levels; in the next one, they'd go down to 42 percent below that baseline; by 2050, 83 percent. All told, if one assumes that emissions decline at a steady rate between each of those milestones, total U.S. greenhouse-gas output between 2012 and 2050 would be equivalent to about 154 billion tons of carbon dioxide. That's 132 billion tons less than if things stayed the same as they are now. (They wouldn't: Without new policies, emissions would probably go up in coming years.) Since it takes 7.8 billion tons of carbon dioxide to fill one part in a million of the atmosphere, the U.S. proposal will save us from a hefty 17 ppm.
What would happen if the United States acquiesced to the demands being made in Copenhagen and cranked down its 2020 target? If the rest of the program were left unchanged, total emissions through 2050 would fall by about another 10 billion tons. With a tougher target in place for 2030 as well, perhaps 10 billion tons more could be avoided. Sounds pretty good, but those additional cuts would yield an extra drop in atmospheric greenhouse-gas concentrations of between 1 ppm and 3 ppm. This is hardly a make-or-break difference when it comes to planetary survival.
Why, then, do so many continue to obsess over getting a new short-term target from the United States? There are three basic reasons. The first is a once-obscure table in the 2007 report from the Intergovernmental Panel on Climate Change. Negotiators have invoked Box 13.7 of that report countless times to support the contention that a 450 ppm target can only be met if developed countries drop their emissions to 25 to 40 percent below 1990 levels by 2020. The studies summarized in that table, though, assumed that most of the world's cuts should come from developed countries—a political judgment, not a scientific one.
The second reason for all this commotion has to do with the fact that the present U.S. target looks much weaker than the one proposed by the EU. Europe has promised to cut its emissions by at least 20 percent from 1990 levels over the next decade, compared with 4 percent from the United States. The difference, though, is less than meets the eye. If you look to 2005 levels as the benchmark, then the EU target is equivalent to a 15 percent cut versus 17 percent for the United States. In other words, the Europeans have already cut their emissions significantly since 1990, so their new target won't demand as much of a sacrifice in the future. To be sure, Europe deserves credit for having put some strong policies in place that have already helped keep emissions down. But the bulk of their success prior to 2005 can be chalked up to the collapse of Eastern Europe, to Margaret Thatcher's breaking of the British coal unions, and to lower population growth. When all is accounted for, the difference between Europe and the United States is meaningful but marginal.
The third reason for international opposition to the U.S. plan is more subtle. Many argue that if the United States adopts more ambitious goals for 2020, others, such as China, will expand their efforts, too. That leverage could, in principle, increase the climate benefits of a stronger U.S. target manyfold. In reality, though, China—and other countries in similar positions—will set their policies based primarily on their own economic, security, and air-quality interests as well as the degree of financial assistance they can get from other nations.
To be certain, the 2020 targets matter a great deal. If the United States left its emissions untouched for the next decade and then tried to hit its target for 2030, the necessary cuts would become so drastic and disruptive that they'd never pass the legislature. That's why we need a plan that starts now but intensifies over time. Indeed, economic models of the Waxman-Markey legislation show that its path to 2020 will make the goals for 2030 and 2050 achievable.
In an ideal world, the United States would move more quickly. But deeper cuts for 2020—and a difference of 1 ppm to 3 ppm in the atmosphere—are not a necessity. Insisting on them could scuttle an international deal or provoke such a backlash in the United States that the climate bill would never pass. And that would be the real environmental tragedy.