Climate Policy Interventions Have a Dismal Success Rate, Study Shows

If you won the lottery 4.2 percent of the time you played, you would be the luckiest person alive. But if you paid your taxes in 4.2 percent of the years you worked, you’re joining Al Capone in Alcatraz.

In other words, while a low success rate in certain arenas might be fine; government policy interventions should probably be aiming a bit higher, especially when failure has an inertial component dooming the planet to irreversible-on-human-time-scales catastrophe. Alas: A study published Thursday in Science found that of 1,500 climate policies studied across dozens of countries between 1998 and 2022, only 63 actually produced significant emissions reductions.

“Our findings demonstrate that more policies do not necessarily equate to better outcomes,” said co-lead author Nicholas Koch, of the Potsdam Institute for Climate Impact Research, in a press release. “Instead, the right mix of measures is crucial.”

Using an OECD database, the researchers analyzed a host of policies from 41 countries on six continents whose collective emissions represent more than 80 percent of the global total. The policies ranged from subsidies and building codes to regulations and taxes, and they examined how well these worked as standalone interventions or as part of a mix of efforts. They then used a machine learning tool to find “breaks,” or large reductions, in emissions, and then tied those breaks back to the actual policy maneuvers. The result is not particularly pretty.

Of 69 such breaks identified, they were able to definitively tie the emissions cut to policies implemented inside a two-year window in 63 cases. More breaks occurred in the buildings sector than others, followed by transport, industry, and electricity. And crucially, a large proportion of the breaks were connected to two or more policies, rather than a standalone move — 70 percent of them.

“Subsidies or regulations alone are insufficient,” Koch said. “Only in combination with price-based instruments, such as carbon and energy taxes, can they deliver substantial emission reductions.”

The specific combinations that can be effective vary substantially, both across sectors and across countries. In rich countries, combining carbon pricing with subsidies can have a large effect; in the developing world, regulations seem most useful, though even more so when combined with the pricing-subsidy duo. There are definitely some insights to be gleaned here — and the researchers have made it easy for the rest of us to join in, launching a free tool where you can find the mix of policies that has offered the best results.

There is some good news in the data — sort of. The number of climate-focused policy measures has increased over time, with each country featuring between four and eight by 2022; they don’t work, but at least there’s a lot of them.

The authors called the results “clear yet sobering” as they relate to the challenge ahead: an emissions gap of 23 billion tons by 2030. They calculate that even if all the countries studied were to repeat past policy successes, an effort about four times the size of those previous wins would still be necessary to close the gap.

“While it remains challenging to precisely disentangle the effects of individual measures within a policy mix, our 63 success cases provide systematic insights into effective policy combinations, and show how well-designed policy mixes depend on sectors and the development level of countries, said co-lead author Annika Stechemesser, also from the Potsdam Institute. “This knowledge is vital for supporting policymakers and society in the transition to climate neutrality.”