The Senate Just Quietly Passed a Major Climate Treaty

America is in the middle of a mini–golden Age of climate policy.

A collection of old refrigerators
Christian Charisius / picture-alliance / dpa / AP

What if the Senate passed an international climate treaty—a pact so powerful that it could avert nearly 1 degree Fahrenheit of global warming—and nobody noticed?

That’s more or less what happened a week ago. Last Wednesday, the Senate ratified the Kigali Amendment, a treaty that will phase out the world’s use of hydrofluorocarbons, or HFCs, a climate pollutant used as an industrial refrigerant and in sprayable consumer products. Because HFCs are hundreds of thousands of times more potent at capturing heat in the atmosphere than carbon dioxide, the Kigali Amendment, which has already been adopted by 137 countries, is the most significant environmental treaty that the United States has joined in at least a decade.

But just as striking as the fact that the United States joined the treaty was how it did it. The vote to ratify Kigali was bipartisan, with 21 Republicans and 48 Democrats voting in support. Yet the move didn’t break through to the extent that other recent climate news has. “It’s very important, and nobody’s picked it up,” Michael Oppenheimer, a geosciences and international-affairs professor at Princeton, told me. In fact, even he didn’t know the treaty had actually been ratified until I told him.

It deserves more attention. The Kigali Amendment was finalized by negotiators in Kigali, Rwanda, six years ago, updating the Montreal Protocol, a three-decade-old treaty. That pact was first adopted to eliminate chlorofluorocarbons, or CFCs, a class of chemicals that were found to be destroying the ozone layer. It has proved to be one of the biggest environmental victories of the past decades: CFCs have since been successfully phased out—and the gap in the ozone layer that those chemicals opened has begun to close.

The Montreal Protocol was updated four times before the Kigali Amendment, but this tweak is different. Instead of helping protect the ozone, this tweak was designed to specifically reduce greenhouse gases.

Regardless, the muted response after the Senate’s move might be in part because the United States had already essentially decided to comply with the treaty, even if it declined to ratify it. In December 2020, Congress passed stringent targets for eliminating HFCs from the economy as part of its lame-duck COVID stimulus bill. (The same piece of legislation sent $600 checks to every American.) That bill is projected to eliminate the equivalent of roughly 900 million metric tons of carbon-dioxide pollution by 2036, more emissions than Germany produces in a year. But America’s full ratification and participation in the treaty will keep the legal regime that underpins the agreement strong.

The Montreal Protocol and its successive amendments are binding treaties with an enforcement mechanism: While the affected chemicals get phased out, only countries that are party to the treaty can trade the chemicals or goods that include them with other countries. This creates a form of lock-in for American companies exporting their products, Nina Kelsey, a political scientist at George Washington University, told me. American industries have tended to support the Montreal Protocol because they benefit from it. That has been true since the 1980s, when DuPont, the sole company that made a replacement chemical for CFCs, argued that the Reagan administration should join talks over the deal that became the pact.

That’s one big reason the U.S. has remained so engaged in the Montreal process even as it has taken a far less active approach in other international treaties. It’s also why Republicans have historically remained friendlier to the Montreal approach relative to other climate policy.

Even so, it wasn’t a sure thing that the United States would join this treaty, even if it had already agreed to abide by it. That the Senate got it done caps an unprecedented year for American climate policy. “Ratifying the Kigali Amendment, along with passing the Inflation Reduction Act, is the strongest one-two punch against climate change any Congress has ever taken,” Senate Majority Leader Chuck Schumer, a Democrat from New York, said before the vote. Normally, such partisan triumphalism is worth ignoring. But in this case … I think he’s actually right?

In fact, after so many years of doing next to nothing on the climate, America seems like it’s in the middle of a mini–golden age for climate policy making. Apart from the IRA, Congress has also passed smaller bills, including the bipartisan infrastructure bill and the CHIPS and Science Act, that implement a dramatic new industrial policy and could increase federal spending on energy R&D.

At the same time, California has vowed to ban new sales of gas-powered cars by 2035, and American automakers have made multibillion-dollar investments in a future where they mostly build and sell electric vehicles. The issue isn’t solved, of course: More legislation and executive action is needed, and the IRA could still fail as a policy experiment. But Congress is doing more now than it’s ever done.

And it’s taking action through alternate channels, too. The success of the Montreal Protocol “shows that even if the major international focus on dealing with greenhouse gases under the Paris Agreement has been less effective, there are other ways to take a bite at the climate problem,” Oppenheimer said. “In this case, quite a big bite. There is a lot more activity around [addressing climate change] than the stultifying lack of progress in international negotiations sometimes makes it look.”