Most climate policies do little to prevent climate change

Most climate policies fail to significantly reduce emissions and have little effect on halting climate change, meaning governments must work harder to find ways to actually make a difference.

Nicholas Koch of the Mercator Institute for Global Commons and Climate Change in Berlin and his colleagues found this by assessing the impact of 1,500 climate policies implemented in 41 countries across six continents between 1998 and 2022.

The researchers began by using machine learning to identify moments when a country’s emissions fell significantly compared to a control group of other countries not included in the analysis. They found 69 such emissions “breaks” and compared them to a database compiled by the Organisation for Economic Co-operation and Development (OECD) that tracks what climate policies were enacted and when.

Matching policy shifts with changes in emissions is not an exact science, but the team was able to identify 63 of these changes as being due to one or more policy interventions that took place within a two-year period before or after the change, to account for lagged or anticipated effects.

Each of the 63 breaks reduced carbon dioxide emissions by between 600 million and 1.8 billion tonnes, but the researchers found that overall, most climate policies have fallen far short of this level of success. “There are many policies that have not led to significant reductions in emissions, and more policies do not necessarily lead to better outcomes,” Koch said.

Many policies fail because they are too specific, he says. For example, governments might subsidize the purchase of new electric cars, but most cars on the road are not electric, so the impact is minimal. One measure that seems to be very effective is a total ban, for example stopping the use of coal for electricity generation, but these are always used in conjunction with others, making it hard for the team to identify whether they work in isolation.

Politicians are looking for a one-size-fits-all combination of policies, but they’re out of luck: there’s nothing that works for all sectors. Pricing seems to be the most effective tool, especially in reducing emissions in commercial industries, but it’s not the only solution, Koch says. “We’ve found that the most frequently used policy tools – subsidies and regulations – are not enough,” he says. “Only in combination with price-based tools like carbon prices, energy taxes, can we achieve significant emissions reductions.” In other words, people will only reduce their emissions if it hurts their wallets.

“The key value of this paper is that it identifies clear changes in emissions in specific sectors and countries,” says Matthew Patterson of the University of Manchester, UK. He notes that the OECD’s database of policy changes has some limitations because the government documents it draws from are not reported consistently around the world, but he says it is the best available for the purposes of this study.

“We’ve known for some time that climate policies work best in combination, but this study gives us more specific information about which combinations work and in what circumstances,” Patterson says. This will allow us to more aggressively pursue these “breaks” to address the emissions gap and create the policy combinations that most effectively address emissions.

Marion Dumas of the London School of Economics and Political Science said the study should be useful to policymakers, but the team’s methodology, which first looks at emissions trends – the results – and then works backwards to understand the causes, may not fully capture the reality of policy interventions.

“This is a very interesting approach, but there is a lot of uncertainty about how to simulate expected (emissions) trajectories and thereby identify the break,” Dumas said. He also said that the two-year interval around the break may be too short and underestimates the real impact of more gradual, longer-term policy changes.

“It’s important not to overinterpret the headline result that only a small number of policies would reduce emissions,” said Robin Rumboll of Imperial College London, noting that small emissions reductions that the team’s methods didn’t detect could add up to big differences.

Of course, a larger issue in identifying the most effective measures is that policymaking doesn’t take place in a vacuum, and specific policies must be acceptable to the general public. “The political dynamics will determine whether that combination can be implemented in any given country or sector,” Patterson says.

“We know this is going to be very difficult politically,” Koch said, “but the good news is that in general it’s possible to put policies in place to achieve these very ambitious goals.”