It's clear at this point that even if the international climate accord being negotiated in suburban Paris becomes legally binding, it won't include punitive measures like trade sanctions or embargoes on straggler countries that fail to meet their commitments.
The only penalty for falling short on efforts to fight global warming would be the hot sting of shame.
And that's not necessarily a bad thing, many analysts say. In international diplomacy, peer pressure and the risk of losing face can be powerful motivations for a country to keep a promise, particularly on a high-profile issue like climate change.
"Meeting national emissions pledges will emerge as a key measure of international moral and diplomatic standing after a Paris agreement, with countries reluctant to flout their targets and risk being treated as pariahs," said Paul Bledsoe, a former Clinton White House climate adviser.
Some countries led by the European Union still insist that governments accept legally binding targets to reduce greenhouse gas pollution in the Paris agreement, which is supposed to be adopted at the end of this week. But that's a no-go for the US for political reasons. So the negotiations are increasingly focused on creating transparency rules to determine whether countries actually follow through on their pledges.
"Three words: name and shame," said Li Shuo, a climate policy expert at Greenpeace China.
Essentially, the system that is emerging is one with clear rules but no mechanism to punish those who break them, like playing a soccer match without a referee.
"Everything happens in the open in the stadium," Li said. "So if someone fouls another player, even if he doesn't get a red card, he will be booed by the audience."
So does that actually work in international relations? Isn't the incentive to ignore the rules, if it entails some competitive advantage, greater than the fear of being publicly called out for foul play?
There are no easy answers. But there are examples of international agreements without binding rules that nonetheless have had an impact on how countries behave, according to environmental law expert Dan Bodansky of Arizona State University.
In a recent academic article, Bodansky wrote that the 1975 Helsinki Declaration on human rights was successful despite its non-legal nature, "because of its regular review conferences ... which focused international scrutiny on the Soviet bloc's human rights performance."
Conversely, the 1997 climate pact known as the Kyoto Protocol failed despite having binding emissions targets for wealthy nations. The US never joined that pact in part because the targets were binding. And when Canada realized it wasn't meeting its targets, it just dropped out.
"Even having legally binding targets is no guarantee that countries do what they've promised to do," said Elliot Diringer of the Center for Climate and Energy Solutions, an environmental think tank in Arlington, Virginia.
Peer pressure, on the other hand, often influences countries to change their positions in the UN climate talks.
The awkward feeling of being alone against the world can make even the most powerful nations cave in, like in Indonesia in 2007, when the US negotiators were blocking a decision on how to move the talks forward. In a memorable David vs. Goliath moment, a delegate from Papua New Guinea implored the US to either be a leader or "please get out of the way."
His appeal was met with roaring applause, and soon after the US negotiators dropped their objections.
Since the previous attempt to forge a global climate pact for both rich and poor countries fell short in 2009, the US has played a leading role in moving away from a Kyoto-style top-down approach. Joint efforts with China have brought the world's top two greenhouse gas polluters closer and improved the chances of success in Paris, analyst say.
Knowing that internationally binding targets would have little chance of getting Senate approval, the Obama administration has favored letting every country decide its own target. The US pushed for countries to submit their targets well ahead of the Paris conference so that they could be analyzed by governments, scientists, environmentalists and the media before they are anchored in a deal. More than 180 countries did so, though many waited until the very last minute.
"Being exposed to that kind of sunlight, we thought, would cause countries to want to put their best foot forward," US climate envoy Todd Stern said last week. "I think that that's happened."
Though there seems to be a growing convergence in Paris on a deal with non-binding targets but binding transparency rules, that doesn't mean there's not going to be a fight. The breakdown of the Kyoto deal has left many wondering how seriously wealthy countries would treat non-binding goals.
"I think that's a very good question," said Ashok Lavssa, a top negotiator in the Indian delegation. "In the past many countries have not fulfilled their commitments."