The US helped lead nearly 200 countries to an international climate change agreement in Paris this past December.

The upcoming election could determine if the US continues that leadership role, or if it reneges on its commitments to cut greenhouse gas emissions. 

Climate policy falls along party lines

If former Secretary of State Hillary Clinton or Vermont Senator Bernie Sanders wins the White House, US climate policy would, in broad strokes, stay the current course.  

Both Sanders and Clinton agree with the established science that climate change is largely man-made, and have mostly backed President Barack Obama’s climate policies, or pledged to expand them.

Across the aisle, it’s another story. The leading Republican candidates could all be classified as climate skeptics.

Texas Senator Ted Cruz has called global warming alarmists “the equal vent of the flat-Earthers,” because he says they ignore a lack of scientific evidence for man-made climate change.

Florida Senator Marco Rubio is less outspoken on the topic, but he has said he does not believe “human activity is causing these dramatic changes to our climate.”

Rubio, Cruz and Ohio Governor John Kasich all say they’ll scrap Obama’s hallmark Clean Power Plan, which limits carbon emissions from power plants and is a cornerstone of the climate commitments the US made in Paris.

Billionaire Donald Trump hasn’t weighed in on that specific policy, but he did tell Fox News in October that he would cut the agency responsible for limiting carbon pollution, the Environmental Protection Agency.

“[The EPA], what they do is a disgrace,” Trump said. “We’ll be fine with the environment. We can leave a little bit, but you can’t destroy businesses.”

International climate policy experts closely tracking the election

All of this puts international proponents of strong climate action more than a little on edge.

Henrik Selin, a Swede who is a professor of global studies at Boston University, has studied international environmental negotiations for 20 years.

“This is generally seen as a very, very, very big deal,” Selin said of the election.  “The United States is the second-largest emitter in the world, and you’re not going get to the desired reductions in greenhouse gas emissions in the short-, medium- or long-term without very substantive US participation.”

The environmental regulations established during the Obama administration put the US on the way to meeting the carbon reductions it agreed to in Paris. 

But those regulations are not set in stone, says David Goldston at the Natural Resources Defense Council Action Fund.

“Many of them can be reversed, in some cases there are a lot of hurdles to doing that, in some cases fewer,” Goldston said. “But in the end, presidents, especially if they have a Congress that’s willing to go along, can totally shape US climate policy and can re-shape it.” 

Then there’s the Supreme Court. Justice Antonin Scalia cast a decisive vote for a stay of the Clean Power Plan just days before he died. The court will likely decide the plan’s ultimate fate, so if Obama does not name a successor before he leaves office, the policy’s survival may hinge on whether a Republican or Democrat follows him in office.  

Reversal could hurt international credibility

Green energy technologies are developing quickly, and renewables are challenging fossil fuels on price. So US carbon emissions may fall regardless of who wins in November.

Still, if the Clean Power Plan disappears with the next president, much of the United States’ influence on global climate policy will go with it.   

“Obama, when he participated actively in Paris and promised that the US would be a leader in international climate policy, they leaned heavily on the Clean Power Plan,” says Guri Bang, a director at the Center for Climate Change Research in Norway.

“Without the Clean Power Plan, this would sort of bring the US into a situation where it has very low credibility in international agreements,” Bang said.

Europeans have already committed to deeper carbon cuts than the US, and they don’t want their trans-Atlantic partners to do less under a new president, says Miranda Schreurs, head of the Environmental Policy Research Centre at the Free University of Berlin.

Schreurs says she has sat on a dozen panels in the past few months dealing with the world after the climate agreement.  

“There’s not a single panel that I’ve been on where [the election] hasn’t been discussed,” Schreurs said.  

Schreurs says Europeans hope the Clean Power Plan, tightened gas mileage standards, proposed methane limits and appliance energy efficiency rules passed under Obama will last into the next presidency. 

But if they don’t, she’s worried. Carbon cuts in the Paris agreement are voluntary. Even before the Paris agreement legally takes effect in 2020, every country will be looking over the fence to see if the guy next door is keeping up his end of the bargain.

“Without the US showing leadership, you can’t expect that China or India or Brazil or Nigeria or South Africa are going to be willing to act,” Schreurs says. “And I think that’s the biggest fear, that if you have a climate skeptic in office … that could be really a problem for moving forward with the implementation of the Paris agreement.”

And that’s just for the initial implementation.

Starting during the next president’s first term, countries need to start planning to ratchet up their future commitments if they hope to limit global warming to 2 degrees Celsius.

If the US isn’t doing enough to cut greenhouse gasses in the short term, it is not going to be able to compel other countries to ratchet up their commitments in the long-term.

From PRI’s The World ©2015 Public Radio International