Gov. Jerry Brown of California speaks at the Democratic National Convention. More coverage at latimes.com/trailguide.

Whether inside or outside the Wells Fargo Center, it's been a hot week in Philadelphia. Temperatures have reached the mid-90s or above each day, and that's without putting a thermometer to those jeering supporters of Sen. Bernie Sanders at the Democratic National Convention.

But for all the focus on emotion and discord and Russian-hacked emails, one overlooked but quite timely topic gave the Democrats reason to cheer. On Wednesday, climate change science finally got its due on the national political stage (in prime time no less), and it's a pressing issue likely to weave its way throughout the general election campaign ahead, heat wave or no.


Senator Sanders actually raised it on Day One as a central election theme, calling it the "greatest environmental crisis facing our planet." He praised former Secretary of State Hillary Clinton for "listening to scientists" and recognizing the threat posed by floods, ocean acidification and rising sea levels. And he contrasted the position sharply with that of Republican nominee Donald Trump, who has described climate science as a "hoax" while taking the side of the fossil fuel industry against the needs of future generations.

Secretary Clinton isn't exactly a new convert to the issue, but Democrats are clearly getting more aggressive in their attitudes toward fighting climate change. The party platform makes clear that man-made global warming is real and that bolder action is needed, which is quite a contrast to what emerged from the Republican National Convention. In Cleveland, little mention was made of climate change, but there was a call to support greater production of oil, gas and coal, which directly contribute to the problem.

Mr. Trump may yet come to rue the day he decided to ignore the overwhelming scientific evidence — including the prediction published just last year that Mr. Trump's own properties in Manhattan are at risk of flooding worse than the city witnessed with Hurricane Sandy. Earlier this year, it was revealed that the candidate's public positions on the issue don't necessary jibe his investing strategy: His company's application to build a sea wall to protect a "Trump International" resort and golf course in Ireland explicitly identifies climate change as a justification.

Indeed, the slogan, "Do What I Say, Not What I Do" could easily replace "Make America Great Again" as the theme of the Trump campaign. From the Trump brand products manufactured overseas to the 180-degree reversals he's made on abortion rights and Democratic candidates like Ms. Clinton or Michael Bloomberg whom he's supported in the past, the Republican nominee's latest tweets are often in conflict with his own behavior, past or present.

Climate change isn't a subject, as First Lady Michelle Obama might say, easily reduced to 140 characters. But the reality of global warming is getting more obvious every day as record levels of carbon dioxide are recorded in the atmosphere, temperatures rise and glaciers melt. It's not just academics who foresee a crisis but also many leaders in the business community (not to mention the military) whose opinions Republicans claim to respect.

Whether the planet is warming is a topic unworthy of debate on the order of arguing whether the ocean is salty or the universe has billions of stars. What candidates should be arguing over is how best to reduce the output of greenhouse gases. What strategies will work best? How can we spur countries like China and India into greater action? How can we promote alternative energies and create hundreds of thousands of new jobs in the United States?

Ms. Clinton would be wise to make climate change a centerpiece of her campaign. Polls show voters are more concerned about the problem today than they have been at any time since Barack Obama was elected president. That's particularly true among Democrats and independents, the very coalition the Democratic nominee needs to support her this fall. Republicans can stick to their fantasies about global hoaxes, but at some point, Americans are going to figure out something is amiss as flooding worsens and "thermogeddon" approaches.