The Logic of Environmental Metrics

Sustainable development has entered a new era of data-driven environmental policymaking. To meet the ambitious targets outlined in the United Nations 2015 Sustainable Development Goals (SDGs) and the Paris Climate Agreement, countries must integrate environmental performance metrics across a range of pollution control and natural resources targets. A more empirical approach to environmental protection promises to make it easier to spot problems, track trends, highlight policy successes and failures, identify best practices, and optimize the gains from investments in environmental management.

The 2018 Environmental Performance Index (EPI) scores 180 countries on 24 performance indicators across ten issue categories covering environmental health and ecosystem vitality. These metrics provide a gauge at a national scale of how close countries are to established environmental policy goals. Now in its tenth iteration, policymakers, scholars, non-governmental organizations, and the media have relied upon the biennial release of the EPI for policy insights and tracking of trends in sustainability. The EPI turns the latest advances in environmental science with worldwide datasets to form into a powerful summary of the state of sustainability around the world.

Data must be organized and communicated to have a meaningful impact on the policy process. Debates about environmental challenges are often hampered by lack of problem definition, uncertainty about the nature of these challenges, and ill-defined solutions. Gathering data into the EPI helps to resolve these difficulties. The EPI serves as a communication tool for translating complex ideas into simpler, more useful forms. The single, 0–100 score for each country serves as a starting point for deeper discussions. We invite government officials, non-governmental organizations, and citizens all over the world to analyze the sub-scores of the EPI to discern which issues are holding back sustainability. Country scores on the EPI are translated into rankings. The EPI rankings are intended to inspire countries to engage in healthy competition, vying to rise to the top of their peer groups. Backcasting EPI scores from historic data allows countries to track their progress over time. In these ways, the EPI offers a number of insights that are useful for identifying best practices, informing policy agendas, and setting priorities in environmental governance.

Figure 1-1
Figure 1–1. The 2018 EPI Framework organizes 24 indicators into ten issue categories and two policy objectives. Weights used in each level of aggregation shown in parentheses.

The 2018 Environmental Performance Index

Data analysis for the 2018 EPI is based on creating a composite index. We begin by gathering data on 24 individual metrics of environmental performance, as shown in Figure 1–1. These metrics are aggregated into a hierarchy beginning with ten issue categories: Air Quality, Water & Sanitation, Heavy Metals, Biodiversity & Habitat, Forests, Fisheries, Climate & Energy, Air Pollution, Water Resources, and Agriculture. These issue categories are then aggregated into two policy objectives – Environmental Health and Ecosystem Vitality – and then finally the overall EPI. To allow for meaningful comparisons, we construct scores for each of the 24 indicators, placing them onto a common scale where 0 indicates worst performance and 100 indicates best performance. How far a country is from achieving international targets of sustainability determines its placement on this scale. The indicator scores are then multiplied by weights, shown in parentheses in Figure 1–1, and added together to produce scores at the levels of the issue categories, policy objectives, and the final EPI. These scores serve as the basis for country ranks. Indicators are constructed from the most recently available data for each of the 24 metrics of environmental performance. To track changes over time, we also apply the same methods to historic data, in order to show what the EPI score for each country would be in a baseline year, generally ten years prior to the current report. We take the performance of every country and aggregate those data into measurements of global performance. We score these global aggregates on the same 0–100 scale as individual countries, showing the state of the world on each indicator. The results of the 2018 EPI – the scores, rankings, trends, and global aggregates – translate environmental data into terms that are comprehensive and comprehendible.

Report Organization

This report is a comprehensive summary of the 2018 Environmental Performance Index. It proceeds in several sections. First, we discuss the methodology of the 2018 EPI. Then we summarize the results, highlighting key findings of the EPI, global performance, country performance, and trends among peer groups. The remaining chapters give background information on each of the issue categories in greater detail, explanations of the indicators, and discussions of the results. Further details about the 2018 EPI are available on our website,, including data downloads, country profiles, and the Technical Appendix.


Box 1 Protecting the Environment: Implementation of Global Environmental Conventions.

Maria Ivanova and Natalia Escobar-Pemberthy

Countries around the world have taken on international commitments to protect and preserve the environment. To safeguard species, ecosystems, and human health, governments have created international agreements that guide their national behavior to regulate pollution and manage conservation. International agreements such as the Stockholm Convention and the Basel Convention, for example, regulate persistent organic pollutants and hazardous waste respectively. Several conventions safeguard biodiversity by protecting specific ecosystems or by protecting species from specific problems, such as the Ramsar Convention on wetlands or the Convention on International Trade in Endangered Species (CITES).

Implementing the obligations under the conventions reflects the extent to which countries are committed to environmental protection and shows good governance. Yet, the level of implementation has not been empirically measured and is largely unknown. As a result, there is no baseline against which to assess performance, actions, or even expectations; and without empirical evidence, we risk erroneous conclusions. Furthermore, in the absence of measurement of implementation, it is impossible to determine whether the conventions solve the problems they were created to address.

To bridge this gap, we developed the Environmental Conventions Index (ECI), an empirical tool to measure the implementation of global environmental conventions that enables self-assessment and comparison with peers. The quantitative analysis of the ECI is grounded in the national reports submitted by state parties to each convention from 2001 to 2015. At this point the analysis is performed for four agreements: The Basel Convention on the Transboundary Movement of Hazardous Waste (1989), the Stockholm Convention on Persistent Organic Pollutants (2001), the Ramsar Convention on Wetlands of International Importance (1971), and CITES (1973). The analysis can be expanded over time to include other agreements such as the Convention on Biological Diversity, the Convention on Migratory Species, the UN Framework Convention on Climate Change, the UN Convention to Combat Desertification, and the World Heritage Convention.

Environmental conventions introduce obligations for parties to report on their compliance with and implementation of the provisions established by each agreement. The parties to each treaty determine the type of information they want to collect through national reports, including the measures that they have taken, and establish the office or executive body to which the reports are to be submitted. National reports contain two types of information. First, they report on the legal, administrative, and policy measures that state parties adopt or intend to adopt to implement each agreement. Second, they also report scientific data on the state of the environmental problem addressed by each convention at the national level.

Designing the ECI involved a multi-stage process to obtain information to assess implementation and develop a methodology that assures replicability across environmental conventions. We began by identifying the reporting obligations and commitments by state parties. To do this, we collected 2,754 national reports among the four agreements, reflecting responses to a total of 2,184 questions regarding implementation of the conventions. These data are categorized into indicators of obligations, including information, regulation, management, technical, and financial. Country reports are scored from 0-5 for each indicator, with 5 noting full implementation and 0 noting failure to report. These indicator scores are then aggregated to form a composite index for each country, though sub-scores by category are also feasible. Like the Environmental Performance Index (EPI), countries can be ranked by their ECI, both globally and regionally.

Reporting is a challenge in all conventions. As Figure 1—2 illustrates, the average reporting rates for all four conventions show that additional efforts are required. Reporting under the Ramsar Convention, however, is significantly higher than for any of the other conventions. Indeed, 60% of the parties to the Ramsar Convention have fully complied with all of their reporting obligations since 2005. All parties to the convention have submitted at least one report during this period, including countries that joined after 2012, such as South Sudan, Swaziland, and Zimbabwe.

Figure 1-2

Figure 1–2. Compliance with national reporting obligations by convention.

Implementation across the conventions varies. No one country shows the same performance across all conventions. Nevertheless, the findings reveal dynamics that demand further research and analysis and could offer important case studies of best practices. Notably, several countries emerge as top performers. Higher level of development seems to be positively correlated with the implementation of the chemicals agreements – the Basel and Stockholm Conventions. In the biodiversity conventions, developing countries register high levels of implementation. Among the 12 countries with the top ten scores for the Ramsar Convention, nine are developing countries, and four of these – Mali, Uganda, Egypt, and Kenya – are in Africa. For CITES, countries such as the Philippines, Peru, Mozambique, and Nepal, rank among the top performers.

Ultimately, the ECI seeks to measure, explain, and improve the level of implementation across global environmental conventions with the hope of improving their effectiveness in resolving the global risks they were designed to address. To this end, it will be critical for national governments to engage with these findings and commit to improving performance.

In 2016, the research team carried out a project sponsored by the UN Environment Programme on assessing the implementation of global environmental conventions in ten countries around the world. The project’s results confirmed the relevance of the Index as an innovative assessment tool. They showed that positive results correspond to the existence of governance instruments such as regulation and policy frameworks as well as specific initiatives. Relatedly, countries with lower scores face challenges with these same issues.

We also conducted a project, in partnership with the Yale Center for Environmental Law & Policy, to evaluate the relationship between the ECI scores and the EPI scores in selected East African countries. The ECI finds that Djibouti, Ethiopia, Kenya, Rwanda, Uganda, and Tanzania register different levels of progress toward fulfillment of their respective obligations under the environmental conventions. The ECI implementation results correlate with their environmental performance scores in the EPI. Countries that register progress in environmental performance regarding ecosystem vitality, such as Tanzania and Kenya, also have positive results in the implementation of the biodiversity conventions. Both countries are part of the top performers in the implementation of international commitments to protect wetlands, ranking 2nd and 4th in the region. Similarly, countries that are struggling with the implementation of the chemicals conventions register low levels of performance in terms of environmental health in the EPI.

Through engagement with the ECI, additional in-depth case studies of the outcomes that individual countries attain and of the impact on the state of the environment could be developed. In the context of the new United Nations 2030 Agenda for Sustainable Development, learning from the national implementation of the global environmental conventions would be critical to enhancing the ability to achieve the Sustainable Development Goals (SDGs). Countries can identify best practices and chart a course for the implementation of commitments under the SDGs that builds on the institutions already in place to ensure environmental protection under the global environmental conventions.

Support for this project was provided in part by Carnegie Corporation of New York, through the Andrew Carnegie Fellows Program, by the Federal Office for the Environment of Switzerland, and by the UN Environment Programme.