The Volokh Conspiracy - America's Environmental Grade:

Researchers at Yale and Columbia released the 2008 Environmental Performance Index this week. Switzerland and three Scandinavian nations topped the list. The United States did not do so well, however, ranking 39th of the 149 nations rated, largely because of the emphasis placed upon global climate change in the Index. As the New York Times reported:

"We are putting more weight on climate change," said Daniel Esty, the report's lead author, who is the director of the Yale Center for Environmental Law and Policy. "Switzerland is the most greenhouse gas efficient economy in the developed world," he said, in part because of its use of hydroelectric power and its transportation system, which relies more on trains than individual cars or trucks.

The United States, with a score of 81.0, he noted, "is slipping down," both because of low scores on three different analyses of greenhouse gas emissions and a pervasive problem with smog. The country's performance on a new indicator that measures regional smog, he said, "is at the bottom of the world right now."

He added, "The U.S. continues to have a bottom-tier performance in greenhouse gas emissions."

AEI's Joel Schwartz thinks the emphasis on climate was undue and produced quite skewed results.

The U.S. scored 81 on the overall EPI, putting it 39th out of 149 countries. The U.S. scored worse than such environmental edens as Russia, Albania, Croatia, and the Dominican Republic, and barely edged out Cuba, Mexico, and Poland. That alone gives you an idea of the EPI's tenuous relationship to the real environment. But let's dig into the numbers a bit deeper to see how the Yale scientists played their game of let's pretend.

Two words: climate change. Carbon dioxide emissions account for half of the Ecosystem Vitality score and 25 percent of the overall EPI score. The U.S. scored 56 out of 100 on climate change, and that is the main reason for America's low overall EPI. If you look only at the Environmental Health index — in other words, the factors that directly affect people's health — the U.S. scored 98.5 out of 100. In fact, virtually all the world's wealthy countries scored above 95 on this measure.While the Yale researchers style their EPI as a valid measure of a country's overall environmental performance, only one factor — greenhouse gas emissions — accounts for most of the variation in developed countries' EPI scores.

Yale's EPI is misleading in other ways. For example, ozone levels account for 3.75 percent of the overall EPI index score. But according to Yale's report, the score was based on data for 2000 rather than current data. Ozone has dropped considerably in the U.S. since 2000. Fifty-four percent of the nation violated the federal eight-hour ozone standard in 2000. But the violation rate had dropped to 15 percent by the end of 2006. The average number of days per year exceeding the eight-hour standard declined 65 percent over the same period.

In any case, the ozone score isn't even based on measured values, but on the output of a global atmospheric chemistry model whose predictions have little relationship to actual ozone levels across the country. U.S. air quality is among the best in the world. Nevertheless, in a New York Times story, one of the Yale researchers claimed that the U.S. "is at the bottom of the world right now" on regional smog.

The EPI's air quality score also includes sulfur dioxide (SO2). But the score is based on SO2 emissions per unit of populated land (which doesn't appear to be defined in the report), rather than on actual SO2 levels in the air. The U.S. scores poorly here (88 vs. 100 for most countries) even though U.S. SO2 levels are only a fraction of the federal health standard virtually everywhere in the U.S.

Joel Schwartz's colleagues Ken Green and Steve Hayward added their two cents here and here, respectively.

UPDATE: Whether or not the EPI's emphasis on climate change can be justified depends in large part on what the EPI purports to measure. As Tokyo Tom comments, "climate change scores tell us little about the health of a country's domestic environment." So, emphasizing climate change makes the EPI less useful as an indicator of environmental conditions within various countries. This is particularly so because the index does not even attempt to measure adaptation efforts.

If, however, the EPI is not intended to be used as a measure of environmental quality across nations, but as a measure of particular environmental outputs or the stringency of regulatory regimes, then the disproportionate emphasis might be justified. As structured, however, the EPI seems to be something of a hybrid, undermining the usefulness of the results as much more than a cudgel to use against U.S. policymakers for their failure to adopt more aggressive climate measures. Further, the EPI could still be subject to the criticism that its various climate measures are somewhat redundant, and ignore the impact of non-regulatory mitigation efforts.

On air quality, Joel Schwartz's critique is relevant for several reasons because the EPI is purporting to measure air quality insofar as it poses a threat to human health. Unless one believes that U.S. ambient air quality standards are grossly underprotective of human health, it is difficult to argue that U.S. air quality poses a significantly greater risk than that in other countries when most of the U.S. is meeting the relevant standards, as is the case with SO2. Further, the EPI's purported focus on human health makes the reliance on emissions and model projections inferior to measurements of actual ambient concentrations to which people are exposed. Further, as he notes, some of the data is quite out-of-date, lessening the EPI's value as an evaluation of current environmental conditions.

I have no idea how the United States would score if some of these concerns were addressed. These problems nonetheless provide ample reason for skepticism about the meaningfulness of the EPI rankings.

	[Jonathan Adler, January 24, 2008 at 10:59pm] Trackbacks America's Environmental Grade: Researchers at Yale and Columbia released the 2008 Environmental Performance Index this week. Switzerland and three Scandinavian nations topped the list. The United States did not do so well, however, ranking 39th of the 149 nations rated, largely because of the emphasis placed upon global climate change in the Index. As the New York Times reported: "We are putting more weight on climate change," said Daniel Esty, the report's lead author, who is the director of the Yale Center for Environmental Law and Policy. "Switzerland is the most greenhouse gas efficient economy in the developed world," he said, in part because of its use of hydroelectric power and its transportation system, which relies more on trains than individual cars or trucks. The United States, with a score of 81.0, he noted, "is slipping down," both because of low scores on three different analyses of greenhouse gas emissions and a pervasive problem with smog. The country's performance on a new indicator that measures regional smog, he said, "is at the bottom of the world right now." He added, "The U.S. continues to have a bottom-tier performance in greenhouse gas emissions." AEI's Joel Schwartz thinks the emphasis on climate was undue and produced quite skewed results. The U.S. scored 81 on the overall EPI, putting it 39th out of 149 countries. The U.S. scored worse than such environmental edens as Russia, Albania, Croatia, and the Dominican Republic, and barely edged out Cuba, Mexico, and Poland. That alone gives you an idea of the EPI's tenuous relationship to the real environment. But let's dig into the numbers a bit deeper to see how the Yale scientists played their game of let's pretend. Two words: climate change. Carbon dioxide emissions account for half of the Ecosystem Vitality score and 25 percent of the overall EPI score. The U.S. scored 56 out of 100 on climate change, and that is the main reason for America's low overall EPI. If you look only at the Environmental Health index — in other words, the factors that directly affect people's health — the U.S. scored 98.5 out of 100. In fact, virtually all the world's wealthy countries scored above 95 on this measure.While the Yale researchers style their EPI as a valid measure of a country's overall environmental performance, only one factor — greenhouse gas emissions — accounts for most of the variation in developed countries' EPI scores. Yale's EPI is misleading in other ways. For example, ozone levels account for 3.75 percent of the overall EPI index score. But according to Yale's report, the score was based on data for 2000 rather than current data. Ozone has dropped considerably in the U.S. since 2000. Fifty-four percent of the nation violated the federal eight-hour ozone standard in 2000. But the violation rate had dropped to 15 percent by the end of 2006. The average number of days per year exceeding the eight-hour standard declined 65 percent over the same period. In any case, the ozone score isn't even based on measured values, but on the output of a global atmospheric chemistry model whose predictions have little relationship to actual ozone levels across the country. U.S. air quality is among the best in the world. Nevertheless, in a New York Times story, one of the Yale researchers claimed that the U.S. "is at the bottom of the world right now" on regional smog. The EPI's air quality score also includes sulfur dioxide (SO2). But the score is based on SO2 emissions per unit of populated land (which doesn't appear to be defined in the report), rather than on actual SO2 levels in the air. The U.S. scores poorly here (88 vs. 100 for most countries) even though U.S. SO2 levels are only a fraction of the federal health standard virtually everywhere in the U.S. Joel Schwartz's colleagues Ken Green and Steve Hayward added their two cents here and here, respectively. UPDATE: Whether or not the EPI's emphasis on climate change can be justified depends in large part on what the EPI purports to measure. As Tokyo Tom comments, "climate change scores tell us little about the health of a country's domestic environment." So, emphasizing climate change makes the EPI less useful as an indicator of environmental conditions within various countries. This is particularly so because the index does not even attempt to measure adaptation efforts. If, however, the EPI is not intended to be used as a measure of environmental quality across nations, but as a measure of particular environmental outputs or the stringency of regulatory regimes, then the disproportionate emphasis might be justified. As structured, however, the EPI seems to be something of a hybrid, undermining the usefulness of the results as much more than a cudgel to use against U.S. policymakers for their failure to adopt more aggressive climate measures. Further, the EPI could still be subject to the criticism that its various climate measures are somewhat redundant, and ignore the impact of non-regulatory mitigation efforts. On air quality, Joel Schwartz's critique is relevant for several reasons because the EPI is purporting to measure air quality insofar as it poses a threat to human health. Unless one believes that U.S. ambient air quality standards are grossly underprotective of human health, it is difficult to argue that U.S. air quality poses a significantly greater risk than that in other countries when most of the U.S. is meeting the relevant standards, as is the case with SO2. Further, the EPI's purported focus on human health makes the reliance on emissions and model projections inferior to measurements of actual ambient concentrations to which people are exposed. Further, as he notes, some of the data is quite out-of-date, lessening the EPI's value as an evaluation of current environmental conditions. I have no idea how the United States would score if some of these concerns were addressed. These problems nonetheless provide ample reason for skepticism about the meaningfulness of the EPI rankings.