Yale may recently have cut its carbon emissions by 17 percent, but the rest of the country’s green credentials are not quite as sterling — at least according to research released this week by Yale and Columbia environmental experts.

The international Environmental Performance Index, published by the Yale Center for Environmental Law and Policy and Columbia University’s Center for International Earth Science Information Network, ranked the United States 39th among 149 countries on the list of most environmentally conscious nations, putting it behind its “Group of Eight” industrialized peers and 11th among countries in the Americas.

The list — the latest of a series of environmental rankings first issued in 2002 at the World Economic Forum in Switzerland — puts Switzerland at the top, followed by Sweden, Norway, Finland and Costa Rica. Twenty-two members of the European Union outranked the United States.

“The EPI’s climate-change metrics ranking the United States alongside India and China near the bottom of the world’s table are a national disgrace,” said Gus Speth, dean of the Yale School of Forestry & Environmental Studies. “The United States’ performance indicates that the next administration must not ignore the ecosystem impacts of environmental as well as agricultural, energy and water-management policies.”

The 2008 EPI based its environmental performance rankings on 25 indicators from six policy categories — environmental health, air pollution, water resources, biodiversity and habitat, productive natural resources and climate change — explained Christine Kim ’99, Yale Center for Environmental Law and Policy program director and co-author of the study. Countries were assessed on a 100-point scale by how closely they came to internationally accepted goals for performance on these measures.

Kim added that climate change was given greater weight in the rankings this year than in previous years because of its current relevance to policy debates.

“The U.S. has a really mixed portfolio: lots of A pluses, but also some Cs and Ds,” she said. “We have good water and air quality [but] a long history of smog and ozone and one of the highest carbon-emission rates.”

She said the United States’ ecosystem-vitality score — which encompasses measures such as biodiversity, air pollution and climate change — trailed its score on environmental health by a large margin, bringing down its overall rank.

But the country’s poor performance did not come as a shock to Lauren Hallett ’08, a research assistant at the YCELP, who helped collect and analyze data for the study.

“If you tease apart the reasons for the rankings, they make a lot of sense,” she said. “Climate change was a huge part of the reason the U.S. ranking was lower this year.”

In 2006, EPI ranked the United States at 28, she said.

Kim said the study found that a country’s wealth strongly correlates with strong environmental performance — positively with measures on indicators such as water sanitation and air quality, and negatively with those such as greenhouse gas emissions and environmental policies.

Mali, Mauritania, Sierra Leone, Angola and Niger — developing countries where the environment takes a backseat to more urgent economic and social problems, Kim said — occupy the bottom five positions.

But the study shows that policy decisions may trump wealth in countries where environmental policies are prioritized, she added. For instance, Costa Rica, which ranked fifth, outperformed its economic peer and neighbor Nicaragua, 77th, by a large margin, owing to stark disparities in environmental efforts by two countries. The latter’s history of poor governance and economic and political instability may have exacerbated these differences by limiting Nicaragua’s ability to engage in environmental activism, Kim explained.

Kim said the EPI is a policy tool intended to “close the gap between science and policy” by spurring countries to commit to substantial environmental change. Although the results are gradual, she said, the rankings have begun to prompt concrete policy reform.

James Connaughton, chairman of the White House Council on Environmental Quality, committed to placing environmental goals among the nation’s millennium challenges in response to the 2006 EPI, she said. The New York Times reported Wednesday that Connaughton said the Bush administration has instated a program to cut diesel emissions from trucks and off-road engines by 90 percent in the next 10 years to address nitrous oxide emissions that damage the ozone.