President Obama began his State of the Union address Tuesday night by threatening Congress. And, on global warming, that’s a good thing.

This was the threat: Pass a market-based climate-change plan — maybe something like the cap-and-trade program John McCain once proposed — or I will unleash my administration.

What does that mean? The Environmental Protection Agency has already established a web of new clean-air rules, and it still has untapped authority to crack down on existing sources of greenhouse gases — big power plants and factories. This authority comes from the Clean Air Act, a law passed by Congress. Don’t like the EPA’s top-down command-and-control approach to protecting the environment? Doing nothing is not an answer. So pass a plan to cut carbon emissions in a more economically literate way. Put a price on carbon dioxide emissions, a solution right out of an Econ 101 textbook.

This is good for three reasons. The first is that the president seems to be putting climate change high on his priority list. The second is that he isn’t just talking about second-rate or third-rate climate policies but also about market-based approaches. And the third reason is that he isn’t giving up on bigger, better climate policy coming out of Congress. In all, it’s a welcome change from much of his first term, when none of those appeared to be the case.

Now Obama needs to show that his shift is more than just rhetorical. He should engage Congress on climate change, even as he puts the EPA to work. He can start by pulling ideas out of GOP Sen. Lisa Murkowski’s recent energy proposal and try to incorporate them into a bigger plan. Judging from Marco Rubio’s dismissive response to the president Tuesday night — “our government can’t control the weather” — it will be hard to convince many Republicans to do much. But the president can be creative in budget negotiations, when all sorts of things will and should be on the table. A carbon tax, for example, could plausibly play a role in any big tax reform, especially if Republicans can claim they got a lower corporate tax or something else dear to them in exchange. He may also get some political help from the extreme weather lately.

Obama’s inattention to the issue is obviously not the only reason America still lacks an ambitious climate plan. But a disengaged president was one of the many obstacles. On Tuesday night, he showed that he can talk a better game. Now he needs to play.