An international research team has conducted the first comprehensive global evaluation of 1,500 climate policy measures across 41 countries and six continents using artificial intelligence (AI). Published in the esteemed journal Science, this groundbreaking study analyzes the impact of various climate policies implemented over the past two decades, revealing a critical insight: most measures have fallen short of delivering the required emission reductions. Out of 1,500 policies, only 63 were successful, leading to an average emission reduction of 19 percent. A key factor in these successes was the inclusion of tax and price incentives within well-designed policy frameworks.
The debate surrounding climate policy effectiveness often centers on which instruments work to reduce emissions and which do not. However, past evaluations have primarily focused on a narrow set of headline policies, overlooking numerous other measures. This new study, led by researchers at the Potsdam Institute for Climate Impact Research (PIK) and the Mercator Research Institute on Global Commons and Climate Change (MCC), in collaboration with experts from the University of Oxford, the University of Victoria, and the Organisation for Economic Co-operation and Development (OECD), seeks to bridge that gap. To support public access and further analysis, the research team has launched an interactive website, the “Climate Policy Explorer,” which provides a comprehensive overview of the study’s findings, methodologies, and results.
Lead author Nicolas Koch from PIK and MCC emphasized the importance of evaluating less-studied policy measures, stating, “We systematically evaluated policy measures that have rarely been studied until now, providing new insights into well-designed combinations of complementary policy instruments. Our findings demonstrate that more policies do not necessarily equate to better outcomes. Instead, the right mix of measures is crucial. For example, subsidies or regulations alone are insufficient; only in combination with price-based instruments, such as carbon and energy taxes, can they deliver substantial emission reductions.”
The study provides concrete examples to illustrate these findings. For instance, the UK’s success in reducing emissions from coal-fired power generation was only possible when tax or price incentives were implemented alongside bans. Similarly, Norway’s reduction of emissions from cars was effective due to a combination of taxes, subsidies, and regulations. In contrast, bans on coal-fired power plants or combustion engine cars alone did not result in significant emission reductions.
In-Depth Analysis of 1,500 Policy Measures and 63 Success Stories
The study analyzed 1,500 policy interventions implemented between 1998 and 2022, encompassing a wide range of climate policy instruments such as energy-related building codes, purchase subsidies for climate-friendly products, and carbon taxes. Utilizing a new OECD database—the most comprehensive inventory of climate policies to date—the research team employed an innovative approach that combines machine learning with traditional statistical analyses to assess the impact of these policies. The analysis identified the 63 measures that successfully achieved large-scale emission reductions.
Annika Stechemesser, another lead author from PIK, highlighted the importance of this research in guiding future climate policies, stating, “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. This knowledge is vital for supporting policymakers and society in the transition to climate neutrality.”
Climate Policy Explorer: A Comprehensive Resource
The Climate Policy Explorer, an interactive tool developed by the research team, offers in-depth insights into specific countries, sectors, and policy measures. For example, in China’s industrial sector, pilot emissions trading systems, complemented by reduced fossil fuel subsidies and stronger financing incentives for energy efficiency, significantly reduced emissions. In the UK, major emissions reductions in the electricity sector were achieved through a minimum carbon price, renewable energy subsidies, and a coal phase-out plan. In the US, a combination of tax incentives, subsidies for low-emission vehicles, and CO2 efficiency standards led to significant reductions in the transportation sector. Germany’s eco-tax reform and truck toll introduction are also highlighted as successful policy measures in the transport sector.
This study underscores the critical importance of designing and implementing the right mix of policy measures to effectively combat climate change. As the world continues to strive toward climate neutrality, the insights gained from this research will be invaluable in shaping future climate policies.
