Thank heavens for the “average citizen.”

After approximately 4 million debates over the past year, someone finally asked the right and real question about climate change. Ingrid Jackson, over in Section C of the audience in Tuesday night’s debate, didn’t ask if the candidates thought global warming was real, and she didn’t even ask what they would do to fight it. “[W]e saw that Congress moved pretty fast in the face of an economic crisis,” she said. “I want to know what you would do within the first two years to make sure that Congress moves fast as far as environmental issues, like climate change and green jobs.”

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That’s the question. Every thinking person — even, at this late date, the current resident of the White House — understands that climate change is real.

John McCain introduced the first legislation to control it in the Senate years ago, and Barack Obama has forthrightly endorsed the demands that have come from Step It Up and others for an 80 percent cut in carbon emissions by mid-century.

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But the real question is, do they mean it? Given that presidents get to do two or three hard things while in office, will this be one? That’s what Ingrid Jackson understood, and she put her query straightforwardly enough that the two combatants had to deviate at least a little from their set speeches.

McCain said that he had disagreed strongly with the Bush White House on global warming, and that he’d “traveled all over the world looking at the effects of greenhouse-gas emissions.” He insisted that the best way to cut carbon was through nuclear power, and went on to add that he supported hybrid, hydrogen, and battery-powered cars. Americans are “the best innovators, we’re the best producers,” he insisted.

Obama said that climate change presented an opportunity to create 5 million new jobs, and that a “new energy economy … can be an engine that drives us into the future the same way the computer was the engine for economic growth over the last couple of decades.” He called for government investment, and he said quite forthrightly, “we’re not going to be able to deal with the climate crisis if our only solution is to use more fossil fuels that create global warming.”

I agree with parts of both answers — but that’s almost beside the point. The point is that McCain and Obama are, at least rhetorically, engaged. Ready to go. After 20 years of writing and talking and organizing about this issue, it was as close to a real breakthrough as I’ve seen. I mean, their point of disagreement was over who had fought harder for alternative energy in the Senate. For the sixth or so of America that was tuned it, it was a way of saying that all serious folks, even if they disagree on tax policy or the war in Iraq, understand that an adult and mature America must take on global warming.

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There were 6 million questions submitted online for this debate, which meant Ingrid Jackson was a pretty lucky winner.

But you can ask the candidates a question too, which gets at just the same issue, and you can do it simply by clicking here. You can send an invitation to both men, asking whichever one wins in November to make their first foreign trip a visit to the international climate conference that will be held in December in Poland. If they show up, it will not only electrify that meeting and put the world back on track toward some kind of solution — it will also be an indication that climate change really will prove central to their presidency. Be like Ingrid: push these guys.