A recent analysis of global climate efforts by a coalition of researchers found that only a small fraction of the policies implemented over the past two decades have been effective in reducing carbon emissions. The study, which examined 1,500 climate initiatives across 41 countries, found that only 63 of these strategies made a meaningful impact on reducing greenhouse gas output.

“It is easy for countries to say they will reduce their emissions of greenhouse gases, but these statements do not mean that the policies they adopt will be effective,” said Jesse Smith, the senior editor at the American Association for the Advancement of Science. “This work illustrates the kinds of policy efforts that are needed to close the emissions gaps in various economic sectors.”

The research investigated the success of a variety of policies, including bans on coal plants, fossil fuel taxes and emissions trading schemes. However, the study’s lead author, Nicholas Koch, emphasized that the sheer number of climate regulations does not necessarily correlate with better outcomes. Instead, countries that successfully reduced their greenhouse gas emissions did so by employing a diverse mix of policies tailored to their unique circumstances.

“Meeting the Paris Agreement’s climate targets necessitates better knowledge about which climate policies work in reducing emissions at the necessary scale,” the report reads. “Our insights on effective but rarely studied policy combinations highlight the important role of price-based instruments in well-designed policy mixes and the policy efforts necessary for closing the emissions gap.”

For instance, initiatives such as banning the sale of gas-powered vehicles were only effective when combined with tax incentives or pricing strategies. This underscores the importance of a multi-faceted approach to climate policy.

The study also noted that there is no “one-size-fits-all” solution to reducing emissions. Different nations have varying needs and resources, meaning that the most effective strategies for lowering emissions will vary across the globe.