Scarlett Johansson addresses the final session of the Democratic National Convention. Photo by Reuters / Jason Reed.ScarJo is fired up and ready to go. (Photo by Reuters / Jason Reed.)

CHARLOTTE, N.C. — In the hours before President Obama took the stage, there was so much warmth and excitement in the greenroom, where speakers gathered in between presentations, that it felt like a barely contained fire.

Montana Gov. Brian Schweitzer swaggered in with his jeans and bolo tie, released a small roar of excitement, and said to nobody in particular, “Hoo wee! What a great day for America! I am charged. So charged!”

Suits snapped photos with Mary J. Blige, who sparkled so brilliantly in her mini-dress and bling that you might have wondered if she was plugged into a socket.

Scarlett Johansson was all a-dimple as she chatted with fellow speakers, saying, “You were just awesome!” and “It’s crazy out there — America is so fired up!”

Florida Rep. Debbie Wasserman Schultz bounded in with her sausage curls springing up and down and beelined for Gabby Giffords, who was smiling resplendently, her fist punching the air as her fellow Democrats hugged and praised her. Wasserman Schultz and Giffords held each other’s hands and didn’t let go.

Shouts of “I love you, buddy!” and “I’m so proud of you” among the politicians were so frequent that one had the feeling of being at a self-help retreat.

The enthusiasm behind the scenes certainly broke through onto the stage and out into the crowd.

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But here’s what stayed firmly behind the scenes throughout the whole convention: the best arguments in favor of climate action and clean energy.

Consider former Michigan Gov. Jennifer Granholm’s showstopping speech on the recovery of the auto industry:

In Colorado, the auto rescue saved more than 9,800 jobs! In Virginia, more than 19,000 jobs! In North Carolina, more than 25,000! Wisconsin: more than 28,000 jobs! Pennsylvania: more than 34,000! Florida: more than 35,000! Ohio: more than 150,000! And in the great state of Michigan? President Obama helped save 211,000 good American jobs. All across America, autos are back! Manufacturing is rebounding! Why? Because when Mitt Romney said, “Let Detroit go bankrupt,” who took the wheel? Barack Obama!

The crowd was roaring so loud that Granholm’s litany of job numbers was inaudible inside the Time Warner Cable Arena and could only be read on the close-captioned screen.

Delegates celebrate following remarks by U.S. President Barack Obama during the final session of the Democratic National Convention. Photo by Reuters / Jessica Rinaldi.Enthusiasm spilled out into the crowds. Climate talk, not so much. (Photo by Reuters / Jessica Rinaldi.)

Just before she went on stage, I asked Granholm what role she thought stronger fuel-economy regulations have had in Detroit’s recovery.

“They’re helping to drive it!” she said. “For a long time people thought that fuel-economy laws would hurt jobs. Now we know that’s absurd! They’ve created jobs, thousands of jobs building better, smarter, cleaner cars.”

If only Granholm had made this point in her speech.

Throughout the convention, speakers recited the party line about an “all-of-the-above” energy approach, including quick nods to renewable power, but only a couple made even oblique, passing references to climate change. Most of the politicians seemed to fear that climate change would be a non-starter, that it would confuse or scare off voters.

President Obama broke the near-silence on global warming during his speech:

 … my plan will continue to reduce the carbon pollution that is heating our planet — because climate change is not a hoax. More droughts and floods and wildfires are not a joke.

It was a relief to hear him actually mention the issue, but a disappointment that he took a defensive not-a-joke stance. He should have presented climate change as a threat not just to the planet but to America’s economy and entire future, and he should have presented climate action as a driver of economic progress.

At a time when a scorching hot summer is drawing to a close, when hundreds of thousands of Americans are living in areas wracked by drought and wildfires, when Gulf Coast residents are still recovering from Hurricane Isaac, Democratic leaders had a responsibility to address the threat of climate change more directly, and celebrate its potential to catalyze American innovation.

Instead, the greenest ideas in the greenroom never made it up on stage.

We can only hope that the euphoric confidence generated at the convention — and the loud cheers Obama got for saying the words “climate change” — will help Democrats overcome their hesitancies and push harder to address this greatest of all challenges.