Actor Joseph Gordon-Levitt, U.N. Secretary General Ban Ki-moon and Sen. Chuck Schumer (D-N.Y.) were among the estimated 100,000 demonstrators who joined the People's Climate March in New York on Sunday, demanding action on the issue of climate change. (Divya Jeswani Verma/The Washington Post)

Over 300,000 protesters marched through Manhattan Sunday, calling for serious action to mitigate global warming ahead of a meeting of world leaders at the United Nations Tuesday. The demonstration will not affect public opinion, predicted Stanford University's Jon Krosnick, who has been conducting and analyzing surveys on climate change for 20 years.

Public opinion, however, is basically irrelevant at this point. Americans have long agreed that climate change is real and needs to be addressed, researchers have found. "They believe it’s at least a moderately serious problem for the nation the world in the future. These are sometimes very large or huge majorities," Krosnick said.


Go home, dirty hippies. Our dysfuncational political system doesn't care what you have to say. (Reuters/Eduardo Munoz)

Sometimes, if pollsters don't ask the question in a clear and direct way, then the numbers look smaller, but in general, researchers' results have been consistent throughout Krosnick's career. One typical survey he conducted found that 74 percent of people believed that the earth was getting hotter and 75 percent thought that humans were largely to blame.

These findings accord with what researchers know about Americans' environmentalism in general. Between six and seven in ten are at least sympathetic to the environmental movement, and they're willing to make some sacrifices, too. Except for a few years after the financial crisis, Americans have always been more likely to say that protecting the environment outweighs economic growth than the opposite.

As many as one in four voters would be willing to sign a pledge or make a donation in support of action on climate change, surveys have found. That's at least as many as are equally concerned about other issues such as guns or abortion, Krosnick noted. The demonstrators in New York are unusually passionate about climate change, but there's no issue that turns every man, woman and child out into the street. Support for mitigating global warming is about as wide and deep as anyone could expect.

Voters are also unpersuaded by the usual arguments against taking action on global warming. Only 18 percent believe that slowing climate change would cause unemployment, and only 14 percent think the United States should wait for other countries to go first.

"Public opinion is already exerting all the pressure that it can exert on government," Krosnick said. Yet government has not responded to the pressure in a meaningful way.

True, the Obama administration's improved standards for fuel economy in cars and trucks will do more to reduce global emissions than any other single policy adopted by one country, unless you count China's one-child policy. Still, our cars will remain much less efficient than Asian and European vehicles. The administration is also planning new regulations on power plants and is working with industry to restrict warming pollutants other than carbon dioxide, but there is much more that needs to be done, and that would require Congress.

The House passed a cap-and-trade bill in 2009, but lawmakers didn't have the votes to break a filibuster in the Senate. The tea party movement had caught Republican lawmakers by surprise, frightening vulnerable Democrats in conservative states as well. Many incumbents did not want to be associated with an effort to slow global warming. Former Rep. Bob Inglis, a deeply conservative, six-term congressman from South Carolina, was trounced in a primary in part because he supported a carbon tax.

But even among those who affiliate with the tea party or describe themselves as "very Republican," polls show that only about half deny the reality of global warming. Really explaining why Congress hasn't done anything on climate change also requires a close look at the energy industry, which spent $454 million on lobbying in the 2010 election cycle alone.

There are many reasons why the U.S. government has acted in a meaningful way to prevent global warming. Public opinion is not one of them.