The Environmental Performance Index (EPI) featured prominently in the recent debate between Peter Foster and David Boyd in Financial Post (The nature debate part 1 and The nature debate part 2, January 25, 2013).

Over the past ten years the EPI has used measureable environmental information to rank countries based on their environmental performance.  The EPI team from Yale and Columbia universities pores over data on the environment, comparing it with wealth, governance, and trade, among many other aspects of well being. First and foremost, we have learned that these relationships are complex, and that a few lines of text often lose the larger message in the data. The debate between Messrs. Foster and Boyd is no exception, and in this case, losing the message of the EPI means losing perspective on the nature of Canada’s environment and economy.

Wealth and the environment

Both Foster and Boyd reference theories on the relationship between wealth and the environment, with Foster arguing the two variables are correlated and Boyd questioning the strength of that relationship. The EPI provides some real-world insight.

EPI data show that although there is a relationship, a nation’s wealth only marginally explains its final EPI ranking. This means that there are other important factors influencing environmental performance. Put differently, economic development matters, but other factors are more important. Although we have not identified every variable, we are confident that environmental performance is not an accident of history and factors such as pragmatic and enforceable environmental safeguards are key.

On climate

Foster notes that Canada scores poorly in the overall EPI and blames our devotion “to official climate alarmism,” arguing that we weigh the Climate Change and Energy category of the EPI too heavily. While Canada does rank 102 out of 132 countries in the Climate Change and Energy analysis, Brunei Darussalam, Czech Republic, Luxembourg, Netherlands, Poland, and Taiwan all manage a better overall EPI rank with a lower Climate score. Furthermore, the Climate Change and Energy category actually receives less weight in the 2012 EPI than it did in 2010—a decrease from 25 percent of the overall EPI score to just 17.5 percent.

In addition, we have anticipated much of Foster’s climate-related concern by choosing CO2 emissions measures that account for his critiques— specifically, differences in wealth and in country size. The EPI indicators that address these concerns are CO2 per GDP (to account for differences in wealth between nations) and CO2 per capita (to account for differences in population size between nations). In the future, perhaps we can cut countries like Canada slack on account of higher latitudes and greater needs for heating—though energy needs for cooling in lower latitudes might balance the equation.

Unequal weights

Foster is also concerned that our Environmental Health objective is not weighted as heavily in the final EPI score as its counterpart objective of Ecosystem Vitality. His concern is valid. Throughout the development of each edition of the EPI we consult with science and policy experts to fine-tune our methodology, and a departure from equal weights within the EPI framework is a signal that we have picked up on something important. It turns out that equal weights do not necessarily mean equal influence (something we discuss briefly in the blog post “the Science and Art of Quantification” and in our upcoming manual “How to Build Green Indices: Learning from the Experience of the Environmental Performance Index”).

For the 2012 EPI, a 50-50 weighting for Environmental Health and Ecosystem Vitality meant that the overall EPI scores were too heavily influenced by performance in the Environmental Health objective alone because of its wider distribution. Countries that perform high in the Environmental Health objective were likely to perform better in the overall EPI, regardless of their scores in Ecosystem Vitality. Both Health and Ecosystems are important and we adjusted the EPI weightings to correct for this imbalance.

An Invitation

Finally, Mr. Foster brushes off the significance of the Environmental Performance Index because of its “murky metrics.” The response here does not require any complicated analysis. Our entire process, from data to methods to the final ranking, is entirely available online and is free and open to the public. Nothing could be less murky. Any journalist, researcher, or policymaker who wishes to dive in is more than welcome, and we are here to help.

On that note, to Messrs. Foster and Boyd: we would like to invite you both to serve on our expert panel for the 2014 EPI. You’ll find that it’s a dynamic group of scientists and practitioners, ready for debate, eager to prepare the best set of tools possible for policymakers.