An analysis of 1500 climate policies in 41 countries has found that a slim minority have led to a significant reduction in carbon emissions, with most policies being too specifically targeted to make a substantial difference
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| Most political efforts at tackling climate change have little effect (Credit: Shutterstock) |
The vast majority of climate policies fail to significantly reduce emissions and so make little difference to stopping climate change, suggesting that governments must work much harder to identify ways to actually shift the needle.
Nicolas Koch at the Mercator Research Institute on Global Commons and Climate Change in Berlin and his colleagues discovered this by assessing the impact of 1500 climate policies put into force between 1998 and 2022, covering 41 countries across six continents.
They began by using machine learning to identify moments in which a country’s emissions dropped significantly, relative to a control group of other nations not included in the analysis. The researchers found 69 of these emissions “breaks” and compared them with a database compiled by the Organisation for Economic Co-operation and Development (OECD) that tracks what types of climate policies were enacted when.
While matching policy shifts to emission changes isn’t an exact science, the team was able to attribute 63 of these breaks to one or more policy interventions within a two-year interval around the break, in order to allow for lagged or anticipated effects.
Each of the 63 breaks saw a reduction in emissions by between 0.6 billion and 1.8 billion metric tonnes of carbon dioxide, but overall the researchers found that most climate policies don’t achieve anywhere near this level of success. “We have a lot of policies out there that have not led to large emission reductions, and more policies do not necessarily equate to better outcomes,” says Koch.
Many policies fail because they are too specifically targeted, he says. For example, governments may subsidise the purchase of new electric cars, but most cars on the road aren’t electric, so the impact is minimal. One tool that seems highly effective is outright bans – for example, stopping coal being used to generate electricity – but as these were always used in conjunction with other measures, it was difficult for the team to identify if they worked in isolation.
Politicians looking for a one-size-fits-all blend of policies are out of luck, as none worked across all sectors. Pricing seems to be the most effective measure, says Koch, particularly in reducing the emissions of profit-motivated industries, but it isn’t the sole solution. “What we observe is that the most frequently used policy tools, which are subsidies and regulations, alone are insufficient,” he says. “Only in combination with price-based instruments – such as carbon prices, energy taxes – can they deliver substantial emission reductions.” In other words, people only cut back on emitting when doing so would hit their wallet.
“The key value in the paper is in identifying those clean breaks in emissions in specific sectors and countries,” says Matthew Paterson at the University of Manchester, UK. He highlights that the OECD database of policy changes has some limitations because the government documents from which it pulls its content aren’t consistently reported across the world, but says it is the best available for the purposes of this study.
“As they say, it has been known for a while that climate policies can work best in combination, but they give us more specificity about which combinations work in which circumstances,” says Paterson. That can then be used to more aggressively pursue these “breaks” in order to address the emissions gap and mix policies to best tackle emissions.
Marion Dumas at the London School of Economics and Political Science, UK, says the work should be useful for policy-makers, but the team’s method may not fully capture the reality of policy interventions, as it looks at the emission trends – or outcomes – first, then works backwards to find the cause.
“This is a very interesting approach, but bears considerable uncertainty concerning how to simulate the expected [emissions] trajectory and thereby identify the breaks,” says Dumas. The two-year interval around each break may also be too narrow, she says, discounting the real impact of more gradual, longer-term policy changes.
“It’s important not to overinterpret the headline result that only a few policies can be tied to emissions reductions,” says Robin Lamboll at Imperial College London, UK, who points out that smaller emissions cuts not picked up by the team’s method may combine to make big differences.
Of course, a larger problem with identifying the most impactful measures is that policy-making doesn’t happen in a vacuum and any specific policy must be palatable to the general public. “In any specific country or sector, it will be political dynamics that drive whether such a mix can be implemented or not,” says Paterson.
“I’m aware that this is politically a super-challenging thing,” says Koch. “It’s just there is some good news that, in general, it’s possible to have these policies to achieve these very ambitious goals.”
Science DOI: 10.1126/science.adl6547
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