President Obama has a solution to the Gulf oil spill: $7-a-gallon gas.

That’s a Harvard University study’s estimate of the per-gallon price of the president’s global-warming agenda. And Obama made clear this week that this agenda is a part of his plan for addressing the Gulf mess.

So what does global-warming legislation have to do with the oil spill?

Good question, because such measures wouldn’t do a thing to clean up the oil or fix the problems that led to the leak.

The answer can be found in Obama Chief of Staff Rahm Emanuel’s now-famous words, “You never want a serious crisis to go to waste — and what I mean by that is it’s an opportunity to do things that you think you could not do before.”

That sure was true of global-warming policy, and especially the cap-and-trade bill. Many observers thought the measure, introduced last year in the House by Reps. Henry Waxman (D-Calif.) and Edward Markey (D-Mass.), was dead: The American people didn’t seem to think that the so-called global-warming crisis justified a price-hiking, job-killing, economy-crushing redesign of our energy supply amid a fragile recovery. Passing another major piece of legislation, one every bit as unpopular as ObamaCare, appeared unlikely in an election year.

So Obama and congressional proponents of cap-and-trade spent several months rebranding it — downplaying the global-warming rationale and claiming that it was really a jobs bill (the so-called green jobs were supposed to spring from the new clean-energy economy) and an energy-independence bill (that will somehow stick it to OPEC).

Sens. John Kerry (D-Mass.) and Joe Lieberman (I-Conn.) even reportedly declined to introduce their new cap-and-trade proposal in the Senate on Earth Day, because they wanted to de-emphasize the global-warming message. Instead, Kerry called the American Power Act “a plan that creates jobs and sets us on a course toward energy independence and economic resurgence.”

But the new marketing strategy wasn’t working. Few believe the green-jobs hype — with good reason. In Spain, for example, green jobs have been an expensive bust, with each position created requiring, on average, $774,000 in government subsidies. And the logic of getting us off oil imports via a unilateral measure that punishes American coal, oil and natural gas never made any sense at all.

Now the president is repackaging cap-and-trade — again — as a long-term solution to the oil spill. But it’s the same old agenda, a huge energy tax that will raise the cost of gasoline and electricity high enough so that we’re forced to use less.

The logic linking cap-and-trade to the spill in the Gulf should frighten anyone who owns a car or truck. Such measures force up the price at the pump — Harvard Kennedy School’s Belfer Center for Science and International Affairs thinks it “may require gas prices greater than $7 a gallon by 2020” to meet Obama’s stated goal of reducing emissions 14 percent from the transportation sector.

Of course, doing so would reduce gasoline use and also raise market share for hugely expensive alternative fuels and vehicles that could never compete otherwise. Less gasoline demand means less need for drilling and thus a slightly reduced chance of a repeat of the Deepwater Horizon spill — but only slightly. Oil will still be a vital part of America’s energy mix.

Oil-spill risks should be addressed directly — such as finding out why the leak occurred and requiring new preventive measures or preparing an improved cleanup plan for the next incident. Cap-and-trade is no fix and would cause trillions of dollars in collateral economic damage along the way.

Emanuel was wrong. The administration shouldn’t view each crisis — including the oil spill — as an opportunity to be exploited, but as a problem to be addressed. And America can’t afford $7-a-gallon gas.

Ben Lieberman is senior analyst of energy and environmental policy in The Heritage Founda tion’s Roe Institute.