The key to effective climate protection is a combination of measures. A study has examined climate policy in 40 countries over a period of 32 years. An international team has developed statistical methods to evaluate the effectiveness of climate protection regulations.

A combination of measures – from CO2 pricing and mineral oil tax to research and investment in renewable energies – is most effective for climate protection. This is the result of an international study currently published in the scientific journal Climate Policy. The research team, which includes experts from Ludwig Maximilian University in Munich (LMU) and the universities of Barcelona, Lausanne, and Oslo, examined policy measures and their effects on the climate over a period of 32 years (from 1990 to 2022). "Governments are expanding their political efforts to protect the climate, but assessing the impact of individual measures is very challenging due to the growing number of parallel instruments," explains Professor Christoph Knill, head of the Chair of Empirical Theories of Politics at LMU and co-author of the study. In particular, the impact of individual policy instruments can hardly be considered in isolation because the effects of numerous other measures come into play. "The aim of our study was to conduct a country-specific assessment to find out which climate protection measures can bring the greatest benefits."

Effective environmental protection in Norway and Sweden

Using a novel statistical method that allows multiple parameters of individual instruments to be modeled simultaneously, the researchers were able to evaluate the effectiveness of 1,737 individual climate protection rules. In doing so, they ensured that only initiatives with sufficient empirical evidence were included in the model. The researchers concluded that a diverse and comprehensive repertoire of policy instruments is more effective than relying on individual measures. "Effective climate protection does not depend on finding a single, optimal approach," says Christoph Knill. "Instead, policy strategies are effective when several measures are implemented over a longer period of time and are well coordinated." In the publication, the team refers to Sweden and Norway, whose broad packages of measures have proven to be highly effective in climate protection, according to the study.

Guidance for decision-makers

According to the study, certain measures have a particularly lasting effect: carbon dioxide pricing and mineral oil taxation, scientific research on climate, and investments in renewable energies have been above-average effective over longer periods of time and across national borders in combination with a wide variety of other climate protection measures.

The results of the study are intended to provide practical guidance to policymakers in identifying the most effective instruments in their respective national contexts. According to the analysis, countries such as Australia, Canada, and Japan could effectively reduce their carbon dioxide emissions by increasing mineral oil taxes. In addition, the newly developed statistical model can also be applied to other rapidly growing policy areas to assess the effectiveness of measures.

Publication

Xavier Fernández-i-Marín, Markus Hinterleitner, Christoph Knill, Yves Steinebach: "Effective Climate Policies for 'All Seasons': Novel Evidence from 40 Countries." In: Climate Policy 2026