As his second inaugural address made clear, U.S. President Barack Obama is committed to taking action to reduce greenhouse-gas emissions and thus to confront the threat of climate change.

There are plenty of bad objections to taking such action, and we will be hearing a lot of them in the weeks and months to come. Yet one criticism -- let us call it the Sophisticated Objection -- deserves respectful consideration, not least because answering it will help us to specify the steps we ought to be taking.

Those who make the Sophisticated Objection acknowledge that climate change is a serious problem, and that the world’s nations should be doing something about it. They contend, however, that unilateral action by any country, including the U.S., will impose significant costs without producing significant benefits. The underlying problem is that the risk of climate change is a product of two things: the existing “stock” of past greenhouse-gas emissions and the continuing “flow” of such emissions.

Unilateral action by the U.S. would do nothing about the global stock and little about the global flow. China is now the biggest greenhouse-gas emitter on earth, and in developing nations, emissions are growing at an extraordinary rate. The Sophisticated Objection is that if the U.S. acts on its own, it will impose costs on the American people without seriously addressing the climate problem. What’s the point?

It’s a legitimate question, and there are three good answers.

Unilateral Action

The first is that if international action is to occur, the U.S. has to help to lead it, through deeds as well as words. In recent years, international negotiations have stalled. That is partly because, as those who offer the Sophisticated Objection emphasize, developing nations (above all China) have been reluctant to make serious commitments to reduce their greenhouse-gas emissions. But another reason for the lack of progress is that nations haven’t yet been convinced that the U.S. is itself willing to make such commitments. True, action by the U.S. can’t guarantee an international accord. But it may be a necessary condition for such an accord, and it would certainly increase the likelihood that other nations will act as well.

The second answer to those who oppose unilateral action has to do with the need for technological innovation. The critics rightly point out that making significant reductions in greenhouse-gas emissions won’t be cheap. One reason is that many nations, including the U.S., remain dependent on fossil fuels, which are major contributors to these emissions. If the world is to make serious progress in combating climate change, we will have to innovate to develop energy sources that are clean and less expensive. Regulation will likely spur such innovation.

In protecting the ozone layer, regulatory requirements did exactly that, leading to unexpectedly cheap substitutes for ozone-depleting chemicals. True, climate change is far more challenging, but there is no question that regulation would accelerate current efforts to develop cleaner energy sources.

The third argument against the Sophisticated Objection is that it plays down the benefits of purely unilateral action. In 2009, a technical working group of the U.S. government, building on established scientific models, came up with economic values for “the social cost of carbon,” meaning the cost of a ton of carbon dioxide emissions. In calculating the benefits and costs of regulations designed to reduce carbon dioxide emissions, many federal agencies have been using the working group’s central number, which is $22.80 in 2013 dollars.

Carbon Costs

Examples include recent rules intended to increase the fuel economy of motor vehicles and the energy efficiency of appliances (such as refrigerators, small motors and beverage vending machines). These rules have generally been supported by industry. The economic benefits of these rules -- which total billions of dollars -- include significant monetized savings from greenhouse gas emissions reductions.

It is here that answering the Sophisticated Objection can help us to specify what to do. No sensible person thinks that the U.S. should spend billions of dollars to achieve small greenhouse-gas reductions. Some imaginable initiatives should be rejected because they would cost too much and deliver too little. At the same time, the U.S. should not overlook opportunities to produce significant emissions reductions at justifiable expense. Recent regulations have easily passed that test. Future initiatives should be embraced when they do so as well.

Those who make the Sophisticated Objection are correct to emphasize that to limit the risks of climate change, many nations will be required to act. But unilateral action should not be avoided for that reason. On the contrary, pragmatic steps by the planet’s most important nation are likely to help spur action by others -- and to lead to technological advances that will ultimately be in the interest of the world as a whole.

(Cass R. Sunstein, the Felix Frankfurter professor of law at Harvard University, is a Bloomberg View columnist. He is the former administrator of the White House Office of Information and Regulatory Affairs, the co-author of “Nudge” and author of “Simpler: The Future of Government,” forthcoming in 2013. The opinions expressed are his own.)

To contact the writer of this article: Cass R. Sunstein at csunstei@law.harvard.edu.

To contact the editor responsible for this article: Katy Roberts at kroberts29@bloomberg.net.