My colleagues and I released the 2012 Environmental Performance Index (EPI) this past week at the annual World Economic Forum meeting in Davos, Switzerland. Countries that ranked high rejoiced; those low on the list sought explanation.

Nobody wants to look bad.

The EPI is a biennial report produced jointly by Yale and Columbia Universities that ranks countries on their environmental performance across a variety of measures, from pesticide regulation and forest loss to child mortality. There were 22 measures this year, each categorized under one of two overarching categories: environmental health or ecosystem vitality. After long hours of number crunching, the EPI produces a single number that ranks countries against each other. (You can find your country’s rank here.)

The EPI is a representation, not an exact science.

Boiling environmental performance down to a single numerical label requires a complicated and inexact fusion of environmental data with expert opinion and debate. This year is the seventh iteration of the environmental performance measurement work since 2000, and the past twelve years have demonstrated a slow, necessary evolution – a process of trial, error, refinement, and retrial. Earlier versions of the EPI produced some head-scratching results, like listing Cuba as the ninth most environmentally healthy country, and Russia appearing only a few spots behind the United States. This year marks the advent of two dramatic improvements.

First, an important change to the basic methodology better balances environmental health scores against ecosystem vitality. Each of the 22 measures receives a weighting that represents its overall importance. Between 2006 and 2008, for example, the contribution of climate change increased from 10 percent to 25 percent of a country’s overall score, reflecting growing international attention to climate change.

For years, the EPI has given disproportionate weight to environmental health measures. This was an unintentional result of variability in scores; because there was historically much greater variability among environmental health performance, this meant that a country’s EPI score was dominated by its performance among a few environmental health indicators. Countries that scored well in this would score high on the EPI regardless of their performance in ecosystem vitality.

The 2012 results are far better calibrated.

These changes to methodology and updates to data, while necessary, result in rankings that are not comparable over time: a ranking of 43 in one EPI and a ranking of 34 in the next version does not equate to an improvement in performance between the two years, though this comparability is often what policymakers want most – a steady gauge of progress or regress. This year, we found a solution.

Secondly, 2012 marks the pilot of the Trend EPI, which allows countries to see where they stand in terms of their progress or decline in performance over the last decade. The Trend EPI works by “backcasting” the present data, framework, and calculation methodology to determine what a country’s EPI score would have been in 2000. This tool provides a valuable glimpse of how countries have risen or fallen in rankings. The table below illustrates the shift in rank among the projected top-ten countries of 2000:


Taking Latvia as an example, we see that it has risen from tenth position in 2000 to second in 2012 – unsurprising given the country’s recent efforts to maintain forest levels and eliminate coal from its energy mix. This presentation of change over time allows countries to focus on improvement where it’s most needed.

Together, the 2012 EPI and Trend EPI reveal a wide range of environmental sustainability results. They are fed by scientific data that is imperfect, but improving. Our report highlights the overall gaps in environmental monitoring, data collection, and transparency that hamper a comprehensive picture of the global environment.  Even in light of data gaps, however, the ability today to gather and analyze vast quantities of data is unprecedented, but the question remains: what comes from all of this analysis?

The EPI is one instance of putting information to work. At its base, the 2012 EPI shows many countries progressing on the numerous environmental challenges they face. But our analysis also suggests that success among certain issues is overshadowed by the notable, global decline in performance on climate change. We’ve also uncovered substantial gaps in environmental monitoring and data collection, particularly among measures of water quality, which hampers a comprehensive picture of the global environment. Perhaps with a new Rio+20 agreement on the horizon the world will be on a more positive trajectory in dealing with climate change issues for the next EPI release in 2014.