In giving the commencement address at the University of California-Irvine on Saturday, President Obama called on young people to push the climate change issue past its current partisan divide. The speech was particularly notable for Obama’s forthright confrontation of climate change deniers.

He took oblique shots at the silly pseudo-scientific proclamations of Sen. James Inhofe (R-Okla.) and Rep. Dana Rohrabacher (R-Calif.). (Inhofe claimed last year that “We’re in a cycle now that all the scientists agree is going into a cooling period,” while Rohrabacher previously raised the possibility of dinosaur flatulence causing warming in the Mesozoic Era to argue that the causes of climate change are unknowable.) Obama also implicitly went after Sen. Marco Rubio (R-Fla.), who recently ducked a question on climate change by saying he’s not a scientist. As Obama points out, one doesn’t need to be a scientist to act on scientific issues while in public office. One simply needs to believe the overwhelming majority of scientists.

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From Obama’s speech:

When President Kennedy set us on a course for the moon, there were a number of people who made a serious case that it wouldn’t be worth it; it was going to be too expensive, it was going to be too hard, it would take too long. But nobody ignored the science. I don’t remember anybody saying that the moon wasn’t there or that it was made of cheese.

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And today’s Congress, though, is full of folks who stubbornly and automatically reject the scientific evidence about climate change. They will tell you it is a hoax, or a fad. One member of Congress actually says the world is cooling. There was one member of Congress who mentioned a theory involving “dinosaur flatulence” — which I won’t get into. …

There are some who also duck the question. They say — when they’re asked about climate change, they say, “Hey, look, I’m not a scientist.” And I’ll translate that for you. What that really means is, “I know that manmade climate change really is happening, but if I admit it, I’ll be run out of town by a radical fringe that thinks climate science is a liberal plot, so I’m not going to admit it.”

Now, I’m not a scientist either, but we’ve got some really good ones at NASA. I do know that the overwhelming majority of scientists who work on climate change, including some who once disputed the data, have put that debate to rest.

Obama noted that Republicans used to support environmental protection and that majorities of the American public say climate change is a serious problem. Adding that young people are more concerned about climate change than older Americans, and they will bear the brunt of the effects of climate change, Obama said they need to lead the country on the issue.

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It was Republicans who used to lead the way on new ideas to protect our environment. It was Teddy Roosevelt who first pushed for our magnificent national parks. It was Richard Nixon who signed the Clean Air Act and opened the EPA. George H.W. Bush — a wonderful man who at 90 just jumped out of a plane in a parachute — said that “human activities are changing the atmosphere in unexpected and unprecedented ways.” John McCain and other Republicans publicly supported free market–based cap-and-trade bills to slow carbon pollution just a few years ago — before the Tea Party decided it was a massive threat to freedom and liberty.

These days, unfortunately, nothing is happening. Even minor energy efficiency bills are killed on the Senate floor. And the reason is because people are thinking about politics instead of thinking about what’s good for the next generation. …

I’m telling you all this because I want to light a fire under you. As the generation getting shortchanged by inaction on this issue, I want all of you to understand you cannot accept that this is the way it has to be. …

You’re going to have to push those of us in power to do what this American moment demands. You’ve got to educate your classmates, and colleagues, and family members and fellow citizens, and tell them what’s at stake. You’ve got to push back against the misinformation, and speak out for facts, and organize others around your vision for the future.

You need to invest in what helps, and divest from what harms. And you’ve got to remind everyone who represents you, at every level of government, that doing something about climate change is a prerequisite for your vote.

Ezra Klein writes on Vox.com, “It was, politically, a speech that showed Obama is done trying to convince the Republican Party to work with him on climate change and has moved onto trying to convince the public — and, in particular, the next generation of American voters.”

Unfortunately, activating the American people may not be enough either. Klein has a whole list of other reasons to be pessimistic about the prospects for climate action.

And even just building enough public support to pressure Republicans to act doesn’t look likely right now. To see why, look at two other issues on which the majority of the American public agrees with Democrats and supports action, but Republicans are blocking it: gun control and immigration.

In the wake of the massacre at Sandy Hook Elementary in December 2012, polls showed majorities of Americans supporting mild gun-control measures such as reinstating the assault-weapons ban and — by an 85 percent to 12 percent margin — running criminal background checks in gun-show sales. Yet Republicans stymied congressional gun-control bills for two reasons: the distribution of gun-control support, and the intensity gap. According to a Pew poll from January 2013, 55 percent of adults favored the assault-weapons ban, but only 44 percent of Republicans. And those Republicans in favor of the ban would be the most moderate ones, while GOP primaries are dominated by the most conservative voters. Most importantly, the gun-control opponents are loud and passionate; they’re a small movement, but they’re effective at punishing politicians who deviate from their agenda. Thanks to gerrymandered House districts and the disproportionate makeup of the Senate, in which half of senators represent low-population rural states, most Republicans in both the House and Senate aren’t trying to appeal to the majority of voters, just the majority of Republican primary voters. So gun control goes nowhere no matter how well it polls with the public at large.

Immigration reform, which GOP leaders have episodically embraced, shows the way to at least get Republicans’ attention: Republicans must believe that a constituency they might have a chance of winning cares deeply about the issue. Republicans perceive Latinos as far more preoccupied with immigration than any swing voters are with gun control. Seeing the growth of the Latino population, and believing that Latinos might be receptive to their appeals if they got the immigration issue out of the way, Republican leaders have tried to corral just enough votes for bipartisan immigration reform.

But they haven’t been able to do it, because of ferocious opposition from within their base. Consider House Majority Leader Eric Cantor’s (R-Va.) recent primary defeat. While two-thirds of his district as a whole supports immigration reform, his willingness even to consider it is widely viewed as a major reason for his loss, because the conservative Republican primary electorate is not at all representative of his district.

As I wrote last week, if immigration reform can’t happen, the prospects are even worse for a cap-and-trade bill. However, Obama has found the closest thing to a wedge: While Republicans will never embrace climate action just because most people passively support it, or because environmentalists ardently do, young people could entice them. Indeed, millennials’ diversity and liberal social views are one reason that pragmatic Republicans want to get immigration out of the way. The millennial generation is growing in electoral strength, leaning heavily Democratic but showing signs of disappointment with the Democrats. In 2008, Obama won voters under 30 years old by a whopping 34-point margin; by 2012, that figure declined to a merely enormous 24 points. But in the 2012 election, young voters can more credibly be said to have provided his margin of victory. Obama won the key battleground states of Florida, Ohio, Pennsylvania, and Virginia despite losing among voters 30 and older in all of them.

If young voters really did show elected officials that support for climate action is a “prerequisite” for their votes, as Obama suggests, Republicans might eventually take notice.