This photo combination shows Democratic presidential candidate Hillary Clinton(L) on April 4, 2016 and Republican challenger Donald Trump on February 16, 2016. (AFP PHOTO / dskDSK/AFP/Getty Images)

Donald Trump, now the presumptive Republican presidential nominee, has said that “I’m not a big believer in man-made climate change.” Hillary Clinton, meanwhile, is a strong proponent of climate change action, and a supporter of continuing President Obama’s policies on the matter, which include joining and honoring the Paris climate agreement and instituting the Clean Power Plan, which would shift domestic electricity generation onto a less carbon-intensive path.

Now that the race appears to have narrowed to these two, it sets up a situation that many environmentalists have long hoped for — one in which a sharp contrast on climate change between the two candidates means that it might not only come up prominently in an election, but moreover, actually make a difference. (And if Bernie Sanders somehow racks up hard-to-imagine delegate totals in coming races or achieves some kind of convention upset, that contrast would only be heightened further.)

That would be pretty different from other recent elections. In 2012, President Obama and the media alike were widely faulted for rarely talking about climate change. In the 2014 midterms, meanwhile, billionaire Tom Steyer’s super PAC NextGen Climate Action spent $ 74 million, but saw candidates it was opposing win nonetheless in key Senate races.

However, the issue appears to have grown in public salience since then, and new polling data, in combination with the very clear difference between Trump and Clinton on the issue, suggests at least a chance that things might actually be different this time around.

“It is an important issue on which to sharpen the contrast in the general election, particularly with young voters,” says Gene Karpinski, the president of the League of Conservation Voters. Karpinski points out not only that Clinton already talks about climate change on the stump regularly (and that it has been a constant theme in Democratic debates) but that her campaign manager, Robby Mook, formerly headed the campaign of Virginia Gov. Terry McAuliffe, who hit his opponent — Ken Cuccinelli — hard on the issue of climate change.

“In my view, rarely does any one issue decide a Presidential election, but being a climate denier hurts Trump,” adds Democratic pollster and strategist Mark Mellman. “Trump’s position sends a wider signal about being anti-science and anti-environment which will make it very difficult for him to appeal to moderates.”

Granted, there remain plenty of grounds for skepticism — and also ways in which the polling data itself continues to raise doubts. As has perennially been the case, climate change still does not rank among the top priorities of most voters, although it does for a minority, particularly in the liberal Democratic camp. And so far, while it has come up mainly in Democratic debates, it has not been a particularly resonant theme in what has been a pretty off-script and tumultuous election.

“It’s an economically oriented discourse, and it’s very personal, which is why you’re seeing a lot of disruption in the political process at this point, and that’s the focus,” says Republican strategist and pollster David Winston, who said he doesn’t think climate change will compete with this narrative.

Nonetheless, other recent polling data reinforces the idea that if there were ever a year in which climate change could matter, it’s this one — both because of how different Clinton and Trump are, and because of the rising profile of the issue.

March Gallup poll, for instance, found more Americans worried either a “great deal” or a “fair amount” about global warming than at any time since 2008 — at 64 percent. It also found that a record 65 percent believe that rising temperatures are being caused by humans, and that all three major political groups in the U.S. show an upswing in concern. 84 percent of Democrats, 64 percent of Independents, and 40 percent of Republicans told Gallup that they “worry a great deal or fair amount” about the issue.

“Americans are now expressing record- or near-record-high belief that global warming is happening, as well as concern about the issue,” the group concluded.

Other types of analysis also suggest the issue has some potential. “Climate change is the issue that is the most starkly different between Clinton supporters and Trump supporters,” adds Anthony Leiserowitz, who heads the Yale Project on Climate Change Communication, which has conducted a number of surveys on the subject. “Among that set of voters that say that global warming will be one of the key issues on which they base their vote, she has a huge lead over him.”

Here’s a chart showing what Leiserowitz – who collaborates with researchers at George Mason University – means. They found that registered “issue voters” who rate climate change as “very important” to them favor Clinton over Trump more than any other kind of issue voter:


Leiserowitz, A., Maibach, E., Roser-Renouf, C., Feinberg, G., & Rosenthal, S. (2016). Hillary Clinton Has the Support of Seven in Ten Registered Voters Who Say Global Warming Is Very Important to Them When Deciding Whom to Vote For; Only 15% of Trump Supporters Say It Is Very Important. Yale University and George Mason University. New Haven, CT: Yale Program on Climate Change Communication.

So who are these climate issue voters? They are predominantly Democrats (62 percent), to be sure, but 19 percent are also Independents, and 38 percent identify as moderate, according to Leiserowitz’s data. Among Independents who are climate issue voters, 67 percent said the would vote for Clinton, and 12 percent for Trump, Leiserowitz said.

“The Clinton campaign sees polling showing profound political vulnerability on climate for the Republicans generally and Trump specifically, so the Clinton camp intends to push climate themes aggressively, ” adds Paul Bledsoe, who worked on climate issues in the former Clinton White House and is now an independent energy consultant. “They see GOP climate denial fitting into a larger narrative of Trump and the Republicans being willing to deny factual information injurious to the American public just because it doesn’t fit into Tea Party ideology.  That will be a meta-theme of the campaign, and climate fits into it.”

Bledsoe says he would expect the Clinton campaign to focus on climate change in “key swing states that are vulnerable to climate impacts, like Florida, Colorado, Arizona and even Virginia.”

Leiserowitz’s take is that Clinton may have an incentive to make a lot of hay out of the topic (though Trump will not) because it will consolidate her support among liberal Democrats, who now rank climate change, clean energy and broad environmental protections as three of their top eight campaign issues, according to his data. Those who care about it most of all are supporters of Bernie Sanders — whom Clinton certainly needs to rally in the general election.

“She has incentive to talk more about climate change, and because we see that it’s such a stark difference between her and Trump, there may be political advantage there as well,” says Leiserowitz.

Climate change is now a top issue that is “uniting the progressive Democratic donor base,” adds Betsy Taylor of Breakthrough Strategies & Solutions, which focuses on the climate issue.

It’s not just Leiserowitz’s research: A new survey from the Program for Public Consultation at the University of Maryland, for instance, questioned over 4,000 registered voters about climate change policies. Before asking voters for their opinion, the questioners first showed them a carefully researched presentation of the pros and cons of several aspects of the debate, such as the Clean Power Plan and the Paris climate agreement.

It found that 70 percent of the public overall considers it either a very high or at least a somewhat high priority to cut down on greenhouse gas emissions, and even on the contentious Clean Power Plan, similar numbers were supportive after reading through the pro-con briefing on the issue.

“Most people, even people who are supporters of Trump, they do not have a view that this is not an issue, not a problem, and nothing should be done about it,” says Steven Kull, who led the research. “Most have the sense, ‘Well, maybe there’s some problem, maybe we should take some steps, it’s probably worth it, the cost is not that high.’ And another argument that’s very popular is, this is where the world economy is going, in this green direction, we should really be ahead of the curve on this.”

Kull says that especially when you merge climate related concerns with air quality concerns, people are supportive of taking action. And he notes that even among Republicans and especially Independents, there are significant numbers of voters who care a lot about the issue.

“For Republicans, those saying that reducing greenhouse gases is a very high priority is 12 percent, while those saying it not a priority at all is 17 percent,” says Kull. “But for independents very high priority is 26 percent, while not at all a priority is 10 percent.  Nationally very high is 34 percent and not at all is 9 percent.”

Granted, all of this remains hypothetical, because we don’t yet know how Clinton might pursue her attack — although it may have already begun. On CBS’s “Face the Nation” Sunday, Clinton said of Trump, “When he says climate change is a Chinese hoax, what does that mean? Has he ever talked to a scientist, or is he just again assuming a slogan?”

The biggest uncertainty of all, though, is how Trump will respond. Unlike other candidates who might consult the polling numbers above and play defense on the issue, he may be more inclined to keep on saying what he actually thinks.

Based on these numbers, that could play to Clinton’s advantage.