Demonstrators attend the People's Climate March in New York in September. (Porter Binks/European Pressphoto Agency)

In April 2009, as the political right was finding its voice in the tea party, South Carolina Republican Rep. Bob Inglis was making the case for a carbon tax. “I’m a conservative. I believe in accountability,” he said. “Global warming is not a matter of belief. It’s a matter of facts.” He added, “We don’t want to be a party of deniers.”

Most of his party disagreed. A year later, Inglis was trounced in a Republican primary, his staunchly conservative record proving insufficient to overcome this heretical deviation. On the surface, it may appear that little has changed in the intervening years. But cracks are appearing in the climate change deniers’ defenses. Today, the movement to seriously address global warming is gaining unlikely supporters, a potential preview of the tectonic shift to come.

Last month, six major oil and gas companies based in Europe, including BP and Royal Dutch Shell, wrote a letter officially endorsing an international price on carbon. “Climate change is a critical challenge for our world,” they declared. “The challenge is how to meet greater energy demand with less [carbon dioxide]. We stand ready to play our part.” In the short term, these companies stand to benefit from carbon pricing, which would shift demand away from coal. But even if their position is partially self-serving, it’s an important declaration, and one that deeply undercuts the climate change deniers’ arguments. Even oil companies, we can now say, believe climate change is real — and admit it’s something they are causing.

While Exxon Mobil did not sign the letter, its stance has also evolved. For years, the company poured millions of dollars into organizations promoting climate change denial. However, in a report to shareholders last year, an Exxon Mobil vice president said , “The risk of climate change is clear and the risk warrants action.” To that end, Exxon Mobil has expressed support for a carbon tax.

In fact, Exxon Mobil has already responded to the likelihood of international climate action by applying “shadow” carbon prices to its international operations, based on the likelihood that a given country will restrict emissions. As the Nation’s environmental correspondent Mark Hertsgaard pointed out in Businessweek, the company actually revised its U.S. carbon price in the wake of last fall’s “People’s Climate March” in New York. “We look at all kinds of things that affect government policies, and that many people marching is clearly going to put pressure on government to do something,” a spokesman said.

The pressure, it appears, will come from more than marchers, too. Earlier this month, North Carolina businessman Jay Faison, a major Republican donor, announced that he would spend $175 million to encourage his party to embrace climate change as a crisis in need of action. His new organization, ClearPath, endorses a carbon tax that would use the revenues to reduce other taxes. Likewise, Jerry Taylor, president of the libertarian Niskanen Center and a former skeptic of climate change, released a paper in March titled “The Conservative Case for a Carbon Tax.”

These developments are a reflection of broader shifts in public opinion, as evidenced by multiple polls finding that climate change denial is increasingly unpopular outside of Washington. For instance, a Yale University survey conducted by Gallup found that 71 percent of Americans say global warming is real; 69 percent believe that human activity is contributing to the problem; and 62 percent agree that “global warming is an urgent threat requiring immediate and drastic action.” Moreover, while Republicans are split on the question of climate change, a Yale-George Mason University poll found that “half of all Republicans (56%) support regulating carbon dioxide as a pollutant, including conservatives (54%).”

There are, of course, still powerful forces standing in the way of meaningful action to address climate change. According to the Guardian, two right-wing organizations, Donors Trust and Donors Capital Fund, funneled $125 million over three years to groups working to undermine climate science and efforts to fight global warming. And the billionaire Koch brothers, fierce opponents of environmental regulation, remain immeasurably influential among Republican politicians competing for their support. Indeed, as The Post’s Catherine Rampell points out, White House hopefuls Marco Rubio, Scott Walker, Rand Paul and Ted Cruz have signed the “No Climate Tax” pledge sponsored by the Kochs’ advocacy organization, American for Prosperity.

Despite the political obstacles, the recognition that climate change denial is wrong — scientifically, economically and morally — is spreading. The grassroots movement that marched in the streets last year is gaining momentum and finding new allies in business, politics, the Pentagon and even the Vatican, where the pope is expected to stress the devastating economic consequences of climate change in an “unprecedented” encyclical on the environment this week. But with the window to address the urgent dangers of climate change closing, it’s time for everyone in this growing, transpartisan alliance to work together and increase the pressure on our leaders to finally make climate action a reality.

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