The 1997 Kyoto Protocol was hailed as the first international response to climate change – but it didn’t include penalties for countries that failed to cut their carbon emissions.

In 2015, the Paris climate agreement, negotiated by 196 countries, also lacked sanctions against noncompliers. In December 2018, negotiators cut a deal in Poland to keep the agreement alive – but again chose not to enforce compliance.

Why do the world’s politicians keep signing weak environmental treaties? Because it helps them get re-elected, according to a new study by economist Marco Battaglini and a colleague.

Incumbents don’t have the political incentives to push for robust environmental agreements. This bias applies to political parties of all stripes, according to the study, “The Political Economy of Weak Treaties,” which will appear in a forthcoming issue of the Journal of Political Economy.

“There’s a temptation for politicians to just go for weaker agreements, because they’re politically more convenient,” said Battaglini, the Edward Meyer Professor of Economics, who co-wrote the article with Bard Harstad of the University of Oslo, Norway.

“Political incumbents will seek to negotiate and sign treaties strategically and in a way that both ties the hands of the next policymaker and improves the odds of staying in office,” they wrote in the study.

The crux of the problem: Politicians have an incentive to shift the situation to get an electoral advantage. “The politician would like to make the success of the agreement contingent on his or her own re-election and the re-election of the party,” Battaglini said. “And how do you make the success contingent? You make the agreement weak, so that if you’re not re-elected, it won’t be pursued by the challenger.”

When a treaty is weak and not fully enforced, voters are uncertain whether their country will meet the treaty’s obligations. They predict that compliance hinges on whether they elect the incumbent or a political challenger, Battaglini said.

A relatively “green,” environmentally friendly party is more likely to comply with the treaty than a relatively “brown,” less environmentally friendly party, and the average voter’s preferred choice will depend on the sanctions facing a country that does not comply. With a small sanction, the average voter would prefer that the brown party be in power; but with a somewhat larger sanction, the voter would prefer the green party. Either way, the politicians in office improve their chances of re-election by negotiating some version of a weak treaty.

In the study, the authors applied their theoretical framework to data on 31 major environmental agreements signed from 1976 to 2001, involving 151 countries. They found most treaties are considered ineffective, because they lack enforcement mechanisms. “The more recent ones, especially, are voluntary,” Battaglini said. “They’re treaties where everyone commits to do whatever they want to do and they face no consequence if they do not deliver.”

The authors also found democracies are more likely than non-democracies to sign agreements. And when they do, those treaties are more likely to be weak. The U.S., for example, signed 11 agreements between 1989 and 2011, all of which have failed to be ratified within a reasonable time.

“There is some evidence that democracies tend to sign agreements that are not particularly effective while non-democracies, when they sign agreements, tend to pursue those more,” Battaglini said.

“It is important to understand the political game and the constraints facing incumbents who seek re-election,” he said. “Only with such an understanding will we be able to design treaties that are both efficient and politically feasible to implement.”