The 2012 Republican presidential field was largely made up of climate skeptics. As the 2016 field shapes up, that's still the case.
Many of the would-be 2016 contenders will acknowledge that the climate is changing but publicly question the extent to which man-made greenhouse-gas emissions are responsible—if at all. There's strong opposition in the field to President Obama's EPA regulations on power plants, a central pillar of his second-term agenda.
"The federal government has no business attempting to massively reorder the global economy, resulting in policies that kill jobs and keep people from rising out of poverty, all in the name of a theory that can't be proven or disproven," Republican Sen. Ted Cruz from Texas told National Journal.
Yet there are fault lines emerging. Some prominent Republicans eyeing the 2016 race agree there's at least some link between human activity and climate change (see our chart on the fledgling 2016 field here).
Before he dropped out of the 2016 race, Mitt Romney declared himself to be "one of those Republicans who thinks we are getting warmer and that we contribute to that," a rebuke of his 2012 position. New Jersey Gov. Chris Christie has touted efforts to cut carbon emissions. And the GOP-led Senate voted 98 to 1 last month in favor of a resolution declaring that "climate change is real and not a hoax."
But don't expect Republicans to embrace a carbon tax or find their inner Al Gores just yet.
Jon Huntsman was the only major 2012 contender to break with the climate deniers among his fellow Republicans—and went nowhere. And even moderate language on global warming is accompanied with sharp criticisms of the Obama agenda and concerns about the economic impact or effectiveness of U.S. action on emissions.
Climate change may be an issue more difficult to avoid in 2016 than it was in 2012. States will be grappling with how to implement Obama's power-plant regulations, which will also be the subject of high-profile court battles. Pope Francis has been talking a lot about climate change and plans to release a detailed statement, called an encyclical, in March. Republicans' struggles to explain their position on vaccines raises broader questions about the party's relationship with science.
The public also backs federal action on climate change—and candidates who say global warming is real and happening. A recent poll in January by The New York Times, Stanford University, and the think tank Resources for the Future showed that two-thirds of respondents, including nearly half of Republicans surveyed, are more likely to vote for a candidate who says human-induced global warming is happening.
GOP strategist Ron Bonjean says there's little upside to candidates raising the issue of climate science, calling it a "rabbit hole."
"It will take them off the message they are trying to appeal to Republican voters about, which is usually about the economy and national security," said Bonjean, a former aide to House and Senate GOP leaders. But he said that criticizing what Republicans call the economic harm of Obama's regulations is good fodder for GOP candidates.
"The bottom line is that the solutions coming from our Democratic friends about how to deal with greenhouse-gas emissions turn our economy upside down," South Carolina Republican Sen. Lindsey Graham, who once was set to sponsor cap-and-trade legislation before abandoning talks in 2010, said on the Senate floor in January.
"All I ask for is that the solution has to be a balanced solution and you have to account for jobs and jobs lost by regulation," Sen. Rand Paul who has blasted Obama's power-plant rules told HBO's Bill Maher last year.
Wisconsin Gov. Scott Walker plans to challenge Obama's sweeping EPA power-plant regulations in court. "Top-down regulations and mandates from the federal government get in the way of innovation and growth," Walker said in his State of the State address in January. He has also signed the "No Climate Tax" pledge, promising to oppose "legislation relating to climate change that includes a net increase in government revenue."
The GOP electorate seems to embrace that dual message. The New York Times poll found that 48 percent of Republicans said they are more likely to vote for a candidate who wants to fight climate change, but at the same time, 47 percent of Republicans said policies meant to fight global warming would hurt the economy.
But activists and Democrats still need to work to make the topic much more important to general election voters. Polling by the Pew Research Center consistently lists climate change near the bottom when respondents are asked what the biggest priorities for Congress and the White House should be.
Billionaire climate activist Tom Steyer spent $74 million of his own money on the 2014 midterm and governors races (with poor results), and now is planning to try and make climate change important in the presidential race, joining green groups active in elections.
Pew, echoing other polls, also finds that the public is nowhere near as convinced as the scientific community that climate change is mostly human-induced. Just half of adults surveyed believe that, compared with 87 percent of scientists with the American Association for the Advancement of Science, a poll released in January shows. A CBS News/New York Times poll released in September similarly found that 54 percent believe global warming is mainly caused by humans (and there's a major partisan split).
The recent debate on Capitol Hill revealed some clear contrasts in the scientific discussion. Led by leading climate denier Republican Sen. Jim Inhofe ofOklahoma, senators voted 98-1 to endorse a resolution saying that "climate change is real and not a hoax," because the measure didn't attribute it to man-made sources. The Senate subsequently rejected measures saying that humans contribute to climate change, but the GOP contenders split their votes.
Marco Rubio and Cruz voted against the amendment that stated humans contribute to climate change (it was silent on the degree), while Paul voted for it. All three voted against another amendment finding that human activity contributes "significantly" (which is closest to the scientific consensus that humans are the main driver). Only Graham, who has recently put his name on the list of senators weighing a bid, endorsed the "significantly" amendment.
The split is evident off Capitol Hill too, where potential candidates, including former Texas Gov. Rick Perry, question whether there's a human contribution at all, while Louisiana Gov. Bobby Jindal believes there's some level of human influence, though he stops far short of endorsing the widespread agreement among scientists that burning fossil fuels and other human actions have been the dominant driver of global warming since the mid-20th century.
Anthony Leiserowitz, who leads the Yale Project on Climate Change Communication, says the tea party's influence has waned and that Republicans are slowly backing away from strident rejection of global warming.
"I think the days of the last nomination process, where we saw basically nine Republican candidates for president standing on the same stage and eight of them basically saying climate change isn't happening or it's not human-caused and making fun of it, essentially mocking the issue—my crystal ball is cloudy, but I would say that is highly unlikely to happen again," he said.
Leiserowitz said there's a rhetorical shift evident in the recent use of the phrase "I'm not a scientist" by a number of Republicans to deflect questions about global warming.
"What they were trying to do is thread this difficult line between not ticking off their hard-core ideological base, many of whom think climate change is a hoax "¦ and the rest of even their own party and, of course, moderates, who don't have those views really at all," Leiserowitz said. "So that is why they suddenly went to this line, and because, honestly, climate change is not a top-tier priority issue for Americans, so they could largely get away with that in this last midterm, but that is not a sustainable position."
The "I am not a scientist" line has become a Democratic punchline. Obama several times—most recently at his State of the Union address—has mocked the GOP meme.
"I've heard some folks try to dodge the evidence by saying they're not scientists—that we don't have enough information to act," Obama said last month. "Well, I'm not a scientist, either. But you know what? I know a lot of really good scientists at NASA and NOAA and at our major universities."
Obama's State Department has been active player in negotiations aimed at reaching a new climate accord at the United Nations talks in Paris this December, a potential pact that's already under fire from congressional Republicans.
At least two potential candidates—Paul and Mike Huckabee—have already used the topic to highlight what they call Democrats' misplaced priorities.
Speaking at last month's Iowa Freedom Summit, a closely watched early cattle call for 2016 hopefuls, Huckabee took aim at Obama's claim that climate change is the biggest threat to future generations.
"Mr. President, I believe that most of us would think that a beheading is a far greater threat to an American than a sunburn," he said, referring to the beheadings of hostages by the radical Islamic State.
That's basically the playbook Paul used to go after Hillary Clinton a few months ago after the presumptive Democratic front-runner called climate change "the most consequential, urgent, sweeping collection of challenges we face."
"I don't think we really want a commander in chief who's battling climate change instead of terrorism," Paul said in September, adding that Clinton's comment "goes to the heart of the matter on whether or not she has the wisdom to lead the country, which I think it's obvious that she doesn't."