When the Supreme Court put a temporary hold on the Clean Power Plan on Tuesday, it may have done more than just delay President Obama’s climate agenda. It may also have undermined the landmark Paris agreement to control climate change.

The monumental achievement in Paris was not that nations promised large enough emissions reductions to stave off climate catastrophe — they didn’t even come close — but that they set up a process under which every nation is taking action and has skin in the game. The Obama administration helped persuade big developing countries such as China, Brazil, and India to participate. If the U.S., the world’s biggest economy and second-biggest emitter, can’t live up to its promises, will that be demoralizing to the international community, or give reluctant nations another excuse to delay their own cuts? And will it make it harder to get everyone to ratchet up the ambition of their pledges at the next big international climate meeting in 2020?

Experts say that many countries will continue with their action plans no matter what happens in the U.S., because they have their own good reasons for switching to clean energy. “China is [taking action] because its air quality is terrible,” says Jake Schmidt, director of the international program at the Natural Resources Defense Council. “India is doing its renewable build-out for other [economic] reasons. I don’t think it changes what these countries view as in their own interest to reduce emissions.”

But delay by the U.S. could make it harder to count on compliance from other countries. There are no penalties for non-compliance in the Paris Agreement, so the whole system depends on everyone keeping their word. U.S. leadership was essential to getting the deal, and undermining U.S. credibility could hurt the implementation process over the next five years, and especially at the meeting in 2020. “If the U.S. isn’t moving on climate action, it makes it really hard to go back to other countries and say, ‘Do more, we’re delivering,’” says Schmidt.

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If the Supreme Court’s ruling makes it less likely that the U.S. will meet its Paris goals, that could do real damage to America’s credibility. The U.S. pledged to cut its carbon emissions 26 to 28 percent below 2005 levels by 2025, and that goal was based in part on the assumption that the Clean Power Plan would be fully implemented. The CPP is the single biggest component of Obama’s Climate Action Plan. It would reduce carbon emissions from the power sector — the largest source of CO2 in the U.S. — by one-third from 2005 levels by 2030.

The U.S. can meet its Paris targets even if the CPP isn’t implemented until after being upheld by the Supreme Court in 2017. And it may still be possible to meet the targets even if the plan is overturned by the court. Power plant emissions are already dropping without the plan in effect, simply because renewables and gas are replacing coal for economic reasons. Other sectors are decreasing emissions because of other regulations and economic drivers. If a president who cares about climate action moves into the White House next year, he or she could find other ways of meeting our targets. That might include rewriting the Clean Power Plan to pass legal muster, or using other tools such as reforming the fossil fuel leasing programs on federal lands and in offshore areas, and regulating methane leakage from existing oil and gas wells and pipelines.

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But the fact that the Clean Power Plan could get tossed out by the Supreme Court highlights how important it is to elect a president who is committed to fighting climate change. “If this is ultimately overturned on the merits, and we can’t strengthen it over time, and the next administration isn’t supportive of climate action, then the durability of the whole [Paris] regime is called into question,” says John Coequyt, director of Sierra Club’s international climate program.

The Supreme Court’s decision to put a stay on the CPP makes it seem a lot more likely that the court could overturn the rule altogether down the line. Conservative states, some energy utilities, and the coal industry all filed suit against the CPP last fall, claiming that the EPA overstepped its regulatory authority under the Clean Air Act in crafting the rule. These petitioners also asked the courts to put the CPP on hold while the case is pending. The D.C. Circuit Court, which will hear the case against the CPP in June, rejected the request for a stay, as many legal experts expected. So the Supreme Court’s decision this week to grant the stay shocked many observers. In order to get a stay, you have to convince the court that the rule has a likely chance of being overturned. By ordering the stay, the Supreme Court’s conservative majority has basically just said there is a real chance they will vote to do away with the Clean Power Plan.

Moreover, as I explained in November after the request for a stay was first filed, “Petitioners for a stay also have to show that the rule will cause ‘irreparable harm’ to the challenger while the case makes its way through the courts. Since states can easily get extensions until 2018 to submit their compliance plans, and since they don’t need to actually start hitting any emissions targets until 2022, environmental lawyers say that’s a hard case to make, and it’s therefore unlikely that their opponents can convince the court that irreparable harm would be done in the next few years.” And yet the Supreme Court granted the stay. Perhaps the conservative justices are so certain they will overturn the rule that they saw no reason not to issue a stay — even though the irreparable-harm claims are almost impossible to prove.

The White House quickly scrambled Tuesday evening to organize a background press briefing intended to project confidence that the rule will be upheld and the president’s climate policy achievements will be protected. They also criticized the stay, noting that the Supreme Court has never before halted a regulation before review by a federal appeals court. Normally, the Supreme Court doesn’t act on regulations at all until they have been fully adjudicated at the lower court level. “We are very surprised by and disagree with the stay,” said a senior Obama administration official. “Granting a stay in these circumstances is extraordinary and unprecedented.”

Environmental organizations also swiftly blasted the stay. Most did not mention Paris, but the Climate Reality Project drew the connection. “One hundred ninety five nations spoke in one voice in Paris to say climate change is real, caused by humans, and must be addressed urgently,” said the group’s CEO, Ken Berlin, in a statement. “There is no doubt that the Clean Power Plan is the United States’ path forward to turning the agreements made in Paris into a reality.”

The White House argues that this decision won’t undermine Paris. First, they insist the CPP will still be upheld, and second, they point out that power plant emissions have been dropping anyway as the market moves from coal to gas and renewables. They also argue that other nations won’t be easily discouraged. “Our international partners understand that the U.S. system is one where rules get challenged and there is litigation,” said the administration official. “They also follow closely the momentum that we’re seeing in the U.S. power sector. Folks will understand that this is a temporary procedural issue. Through [the Clean Power Plan] and a variety of other measures, we will meet our commitments.”

But the White House cannot control, or even predict, how the intensely ideological conservative judicial activists on the Supreme Court will rule on anything. So what this episode demonstrates is the fragility of any one executive action. The way to ensure that the U.S. can still make climate progress, and reassure other countries that it will continue to do so, is by using every possible means, so that it isn’t overly dependent on any one.

“These regulatory actions are vulnerable and you need to have a robust set of drivers to get where you need to go,” observes Coequyt. Schmidt agrees: “Other tools and levers will be at play. It’s a harder mental conception for the international community. It’s easier to say, ‘We’ve got a rule.’ But the reality for most countries is there’s no one policy, it’s a combination of 12 different policies.”

And now the White House had better get to work on some of those backup plans.