This year’s climate talks in Paris have come with a radically new approach — and social psychologists say this has changed the dynamics around the negotiating table.

Whether it can slow rising global temperatures remains to be seen.

For the last 20 years, the United Nations has searched for a “top-down” solution to climate change, attempting to forge an enforceable international agreement that would compel countries to curb their carbon emissions.

This approach has, by many measures, failed. The sole treaty to emerge from the last 21 years of U.N.-led negotiations was the Kyoto protocol. But the 1997 agreement was never ratified by the United States, the world’s largest polluter at the time, it left loopholes for major polluters like China and India, and on the whole, it failed to slow the pace of global CO2 emissions. Attempts to negotiate more ambitious agreements fared worse, most famously during 2009’s talks in Copenhagen, which even its hosts decried as a “great failure.”

“The failure in Copenhagen was an electric shock that allowed everything in the system to reset,” said David Victor, director of the Laboratory on International Law and Regulation at the University of California at San Diego. “It really opened up the landscape to new ideas. And that’s what we’re seeing now.”

That reset tossed out the “top-down” model and replaced it with a “bottom up” approach long favored by the U.S.: Every country comes to the negotiations with a specific pledge to reduce emissions, but with no legally-mandated goals, timetables or sanctions imposed by the U.N.

Social scientists say the new approach comes with a new psychology, one that potentially sidesteps old sticking points.

Take the issue of fairness. Fairness is big in negotiations, and has been widely studied as a psychological factor that can determine bargaining outcomes. Several studies — including one that polled 155 former climate negotiators — have shown that expert negotiators are highly sensitive to equity, and that nuanced considerations of fairness are more likely to result in a deal.

This is no surprise to people who have followed climate negotiations over the years, where the biggest brawls have often been over what is fair, said Sonja Klinsky, an environmental public policy researcher at Arizona State University. Developing nations like India, China and Brazil have argued that they bear less responsibility for solving climate change since historically, they did little to cause it. But countries like the U.S., Australia and Canada have argued that it’s unfair to make them unilaterally reduce carbon emissions since doing so could give rivals in developing nations an economic advantage. The smallest, poorest countries, meanwhile, argue that they’ve done the least to cause climate change, yet face its gravest consequences.

The top-down approach tried to address the fairness issue by forcing the world’s biggest carbon emitters to make the biggest strides, said Jonathan Pickering, an environmental policy researcher at the University of Canberra in Australia, who has written about the two approaches.

The bottom-up approach sidesteps questions of fairness, allowing each country to decide for themselves what they’d like to do.

The U.S. pledge, for example, is the most ambitious plan the country has offered to date. China has agreed to peak its emissions by 2030. India has for the first time committed to derive 40 percent of its electricity from renewables. Even Russian President Vladimir Putin, whose administration has previously expressed skepticism about climate change, has promised not to stand in the way of talks.

The approach might not slow emissions as effectively, Pickering said, but it has a distinct advantage: “It’s feasible.”

It’s feasible precisely because it doesn’t require fairness to be solved, thereby drawing in participants whose involvement is central for progress, but who otherwise might be reticent to allow international bodies to make decisions on their behalf. The U.S. falls into this category, said Klinsky.

“We just don’t work in community that way,” she said. “We’re used to being the largest player in every room. We do a lot of things unilaterally. Psychologically, it’s an easier sell in America if we’re not being told what to do, we’re able to lead by example.”

Because bottom-up allows every country to participate at the level they’re comfortable with, it fosters a sense of ownership, participation, and even leadership in the process, noted Dale Jamieson, chair of New York University’s Environmental Studies Department.

“Every country gets to think its leader is absolutely front and center in the negotiations,” said Jamieson.

If there is a drawback to the approach, it’s that it leaves the U.N. with no way to force countries to improve their commitments.

Instead, the bottom-up system relies an another psychological tactic, Jamieson said: Shame. Countries who fail to do their share will face attacks on their international reputations, while their negotiators will be forced to confront judgment at the bargaining table. This has worked in other contexts, he said, from students shaming their universities into divesting from oil companies, to human rights conventions, which are less likely to invoke direct sanctions than a slew of international bad press.

“The world of shaming and disapproval and denunciation can be very, very powerful, but it is much more decentralized than a treaty that metes out sanctions,” Jamieson said.

There is evidence that officials negotiating over climate change are vulnerable to this tactic. A 2014 study by Arizona State University climate psychology researcher Manjana Milkoreit examining the emotional experience of climate negotiators concluded that they were not distant or detached from the dangers of climate change, but rather experienced them as a deeply personal threat “over which other negotiation participants have significant control.” This personal investment, the research found, can lead climate negotiations away from arguments rooted in economics, and instead frame talks in more human terms. Klinsky said negotiators can be influenced by having other delegates look them in the eye and make a moral appeal. Negotiations could be directed in small ways by such shame-inducing raised eyebrows, said Jamieson.

Victor has been advocating the bottom-up approach for decades. He was involved in climate negotiations in the 1990s, but says he walked away from the process when it became clear that it would become fixated on finding a single, legally-enforceable solution, which he found untenable. He believes that if negotiations had been bottom-up, more progress might have been made.

“This is coming straight out of the theory of bargaining,” Victor said. “We start with agreements that are in every country’s self interest, through those agreements you start to build credibility and then you start to ratchet forward. Eventually we will build deep credibility and confidence in the process that will really make possible the aggressive commitments that are economically costly.”

Regardless of approach, he said, profound changes might not have been made until now — when the effects of rising temperatures are more apparent — because of another piece of human psychology: The preference for immediate gratification over solving invisible problems.

“People don’t really believe things that are abstract. They need to see evidence, and feel pain,” Victor said. “Unfortunately that means you’re not going to see swift action on a problem until it’s too late to stop the worst effects.”

Scientists like Klinsky still worry that despite the growing urgency, the voluntary nature of the bottom-up approach won’t prevent Earth’s temperature from increasing more than 2 degrees Celsius — the goal the U.N. is aiming for.

“Either way you cut it, our ambition levels are too low. They’re really getting better, but we know the pledges this year are not going to add up to a 2-degree world,” she said. “That’s not fair, because we are imposing profound costs on those who did not cause this problem.”

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