The Paris agreement on climate change that Secretary of State John Kerry signed in Paris on Friday may be the worst accord the United States has ever entered into as a nation.

All agreements are alike in three basic ways.

First, you should get something out of it. Otherwise, why would you sign on?

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Second, all agreements have a cost: you can’t get something for nothing.

Third, all agreements need a way to make sure everyone lives up to the deal. Otherwise, why wouldn’t they cheat? This is the toughest part of international negotiations. It’s hard to find ways to make nations do things that they don’t believe are in their interests.

So how does the Paris accord, which commits the United States to reducing greenhouse gas emissions by at least 26 percent by 2025, stack up on those three basic measures? Terribly.

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What do we get out of it? Supposedly, we’re making a contribution to keeping the planet cool. But surprisingly, while the U.S. Environmental Protection Agency cheerleads for the new regulations, it doesn’t bother to say how much cooler the planet will be if we do what they want us to.

If the regulations were going to be really effective, you can bet the EPA would brag about them. Yet it doesn’t offer a number. One group of researchers found that cutting U.S. emissions will cool the planet by only 0.02 of a degree Celsius. That isn’t much of a contribution.

If that contribution was cheap, it might be worth making anyhow. But in fact, it’s extremely expensive. The U.S. Energy Information Agency predicts increasing the price of fossil fuels will cost us more than $2 trillion by 2030, and result in a million lost jobs.

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Go inside New York politics.

So the agreement has small benefits, and large costs. The Obama administration likes to pump up the benefits by arguing that climate change will cause the sea to rise, hurricanes to spawn, and wars to start.

Even if all of this is true, it doesn’t matter. If all these terrors are the result of rising temperatures, then the Paris agreement can only stop them from happening by making the globe cooler. And U.S. regulations won’t do that.

But what about the rest of the world? If everyone cuts their emissions, won’t that help? That’s where the third problem, enforcement, comes in.

The Paris agreement isn’t a treaty, which would be legally binding on everyone. It should have been a treaty, because it meets all the State Department’s criteria. The reason it’s not is because President Barack Obama realized the Senate would never ratify such a terrible deal.

So all this hoopla is about a “political agreement.” It’s a paper deal. What isn’t just paper are the 368 new coal-fired power stations that China is building, or the 297 such stations that India has under construction. Then there are the 93 planned in Turkey, and the 60 in the Philippines.

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I don’t blame these nations for wanting to make sure that the lights stay on for their people: that’s where their true interests lie. But all those power stations will swamp the effect of U.S. and European emissions cuts. And that assumes that notoriously corrupt China is able to monitor its emissions honestly.

The Paris agreement isn’t going to have any impact on China. It’s only going to hurt the United States, and the European nations that go along with it. It’s like deciding to teach the man in the mirror a lesson by punching yourself in the face.

If you believe in global warming, fine. But if you believe, you should take it seriously. And the Paris deal is not serious: it is not going to reduce global emissions. The only thing it offers Americans is more regulations. Perhaps it’s not such a surprise that the Obama administration signed it after all.

Ted R. Bromund is a senior research fellow in The Heritage Foundation’s Thatcher Center for Freedom.