Republican U.S. presidential candidate Ted Cruz gestures over at rival candidate Donald Trump (L) at the U.S. Republican presidential candidates debate in Detroit, Michigan, March 3, 2016. REUTERS/Jim Young

In late March, when the United States and China jointly declared that they’d be moving to immediately sign and then join the Paris climate agreement “as early as possible this year,” it was seen as the latest show of joint leadership by the two largest emitters.

But there’s another possible implication that went largely unnoticed. If the nations of the world, led by its two biggest contributors to climate change, jump through all the hoops needed to bring this agreement into force before President Obama leaves office, the next U.S. president could have a difficult time — or at least, a long wait — if he or she wanted to get out of it.

The Paris agreement does not state or limit when it can go into effect — it simply depends on when enough countries formally sign and join it. If that occurred while Obama is still in office, “then the next president could not withdraw until sometime in 2019, and the withdrawal would not be effective until sometime in 2020,” said Daniel Bodansky, a scholar of international environmental law at Arizona State University and a former attorney at the State Department focused on climate change.

The top two Republican presidential contenders, Sen. Ted Cruz (R-Tex.) and New York businessman Donald Trump, have both expressed major skepticism about the extent to which human activity is driving climate change. Cruz said in an interview with National Public Radio in December, “The scientific evidence doesn’t support global warming,” and that when it comes to the “theory” of climate change, “this is liberal politicians who want government power over the economy, the energy sector and every aspect of our lives.”

Trump, for his part, has suggested slashing funding for the Environmental Protection Agency–the primary agency responsible for imposing limits on the nation’s carbon output–saying “what they do is a disgrace” and that even if it’s shrunk to a small portion of its current  size, “We’ll be fine with the environment. We can leave a little bit, but you can’t destroy businesses.”

Those positions suggests they would be none too keen about the Paris agreement, which takes climate science as a fundamental premise and seeks to organize the world’s countries into a process that will lead to global emissions reductions, providing a structure and reporting requirements for how individual countries will do so. Republicans have repeatedly said they would seek to overturn several signature Obama policies as soon as they took control of the White House, and reversing his climate rules and agreements rank high on that list. But with an already in-force Paris agreement, that might be pretty tough.

The Trump and Cruz campaigns did not respond to requests for comment for this article.

“Thanks to the president’s leadership, the historic Paris Agreement put in place a framework for all countries to take action to address the growing threat of climate change, and to increase their action and commitments over time,” said White House spokesman Frank Benenati, in response to a request for comment from the Post. “The sooner we bring the Agreement into force, the sooner the framework created by the Paris Agreement is put in place to ensure that all countries are acting and responding to climate change, as we are already seeing and experiencing the effects today and there is no time to waste.”

The text of the Paris agreement was negotiated in December and agreed to unanimously by the 195 countries that are parties to the United Nations’ Framework Convention on Climate Change.

But for the agreement to take effect, two steps must be taken. First, nations must formally sign the agreement — which they can do starting on April 22, when a signing ceremony is being held at the United Nations’ headquarters in New York. The United States and China have pledged to sign immediately then, along with some 130 other countries.

Second, nations must also take further steps to implement the agreement at home, before going back to the U.N. and depositing what are called their “instruments of ratification, acceptance, approval or accession.” After signing, “then they each go through their respective domestic processes to formally ratify, or approve, there’s a whole string of alternate verbs that are used depending on one’s process,” says Elliott Diringer, executive vice president of the Center for Climate and Energy Solutions.

The United States has said that the Paris agreement is not, in its eyes, a formal, legally binding treaty, which means that it doesn’t have to be ratified by the Senate. Thus, the formal process is likely to amount to a presidential order or statement, Diringer said.

When at least 55 countries, who account for at least 55 percent of global emissions, have all moved to join the agreement in this way, the Paris agreement then enters into force after a 30 day wait period. According to data just released by the U.N., the U.S. and China accounted for around 38 percent of emissions, meaning that if the two act swiftly, it will be much easier to meet the emissions threshold. Other big emitters who could then help substantially in getting to 55 percent include Russia (7.5 percent), India (4.1 percent), Japan (3.79 percent), and Brazil (2.48 percent).

White House senior adviser Brian Deese made a point of saying, on a March 31 press call, that the fact that China had indicated it wanted to join the accord “as soon as possible this year” was  “significant.”

“That commitment will help build momentum for expeditious entry into force, which is something both our countries, through this joint statement, are calling for and that we will both be working together and respectively to try to encourage going forward,” he said, adding that having it enter into force will send “a strong, durable market signal to the global economy that we’re moving in the direction of low-carbon solutions, and will help ensure that the critical implementation steps that were left from the Paris agreement will be taken seriously and there won’t be any backtracking.”

Besides the United States and China, it is far from clear how quickly other countries will move in joining the agreement. But “there is a concerted effort now by a significant group of countries to make sure this agreement comes into force before the end of the Obama administration,” says Nigel Purvis, the president and CEO of Climate Advisers and a former State Department environmental official in the Clinton and George W. Bush administrations.

“While success is not guaranteed, the U.S. and China decision to move forward quickly provides significant momentum,” Purvis continued.

On top of that, the BASIC group of countries — Brazil, South Africa (which accounts for 1.46 percent of global emissions), India, and China — recently released a statement saying they would also start domestic moves to ratify the agreement “as soon as possible,” suggesting other major emitters may be moving quickly.

It’s important to note that in earlier drafts of the Paris agreement being negotiated last year, it contained language suggesting that it couldn’t have entered into force so soon. Todd Stern, the U.S.’s special envoy for climate change and the agreement’s chief negotiator, noted on the March 31 press call that these earlier drafts had said it would not enter into force before 2020. “But that language fell out of the final draft,” said Stern, “so as soon as you hit that double threshold [55 countries representing 55 percent of emissions], the agreement is in force. And that could potentially happen this year.”

So suppose that the agreement enters into force before the next president is inaugurated. At that point, to get out of it again, one turns to its Article 28, which states that, “At any time after three years from the date on which this Agreement has entered into force for a Party, that Party may withdraw from this Agreement.” It adds, though, that the withdrawal itself doesn’t take effect until “expiry of one year from the date of receipt by the Depositary of the notification of withdrawal.” So that’s 4 years — the length of a presidential term.

This text, it’s important to emphasize, doesn’t seem to have been meant to trap anyone. It’s boilerplate language, says Arizona State’s Bodansky, and also found in other accords like the Kyoto Protocol and United Nations’ Framework Convention on Climate Change. “It was not negotiated by the U.S. (or any other country) as a means of binding the next president,” he says.

Any attempt to abandon or withdraw from the Paris agreement — either before or after its entry into force — would likely create international uproar.

“Entry into force does in a sense create a higher hurdle in terms of reversing course essentially. But the political consequences are there under any circumstances,” says David Waskow, who directs the international climate initiative at the World Resources Institute.

Granted, even if an unsympathetic U.S. president couldn’t formally withdraw immediately, that doesn’t mean that his or her hands would be overly tied by the agreement. That’s because when it comes to delivering actual emissions cuts, the agreement largely relies on the individual commitments by the world’s nations.

“The provisions of the agreement which would remain in place for three years and that would therefore ‘bind’ a future president are not very onerous,” said John Bellinger, a former legal adviser to the State Department under Condoleeza Rice and currently an attorney at Arnold and Porter. “The Obama administration carefully negotiated the Agreement to ensure that the binding provisions are not so burdensome as to require the agreement to be treated as a treaty for purposes of U.S. law, thereby requiring Senate advice and consent. The administration has already complied with one of the binding provisions, which was to announce a carbon reduction goal. But the agreement does not require a future president actually to achieve that goal.”

So, the administration of a future President Trump or Cruz would presumably have to report to the U.N. on how it is going about implementing the Paris agreement, and how it intends to cut emissions (whether it actually does so or not). The agreement gives the United States “a responsibility to have a climate plan and to report transparently on progress to the international community,” says Purvis.

And what if a future administration didn’t even do that? Failure to comply with the agreement does have some consequences, though they too do not appear to be very onerous. The text lays forth a “compliance” mechanism in the form of a “committee” that would be “non-adversarial and non-punitive.”

“The premise of the Paris agreement is one of political pledges and political accountability,” says Purvis. “And the consequence for not complying is international criticism. And the need to explain oneself.”

Still, it appears that an increased global desire to move fast on getting the agreement implemented, combined with some boilerplate language, does create a situation in which an in-force agreement would be fairly tough for the next president to get out of.

“Countries gave considerable thought in Paris to creating a durable agreement that would outlive occasional lapses in political will,” said Purvis.

Read more at Energy & Environment:

This huge region of Brazil is even more deforested than the Amazon

Tesla’s Model 3 orders are through the roof.  Here’s what that means for the planet

Greenland and Antarctic melt isn’t just raising seas — it’s changing the Earth’s rotation

For more, you can sign up for our weekly newsletter here, and follow us on Twitter here.