The Yale Center for Environmental Law and Policy, has published its 2005 Environmental Sustainability Index which rates the ability of nations to protect the environment over the next several decades. Using 76 data sets, including natural resource endowments, past and present pollution levels, environmental management efforts, and a society’s capacity to improve its environmental performance, the study develops 21 indicators of environmental sustainability.

While it appears that no country is on a fully sustainable trajectory, at every level of development, some countries are managing their environmental challenges better than others.

The study finds that the factors that corelate most highly with a high overall score are civil and political liberties, government effectiveness, political institutions, and participation in international environmental agreements.

Sam Pizzigati, author of "Greed and Good" takes the analysis one step farther, suggesting that there is also a strong relation between income inequality and a high sustainability score.

The top two nations on the environment list, Finland and Norway, just happen to be among the most economically equal nations in the world, as is the fourth-best nation on the list, Sweden.

Uruguay [number 3 on the list], meanwhile, has been Latin America's most economically equal country for most of the last century.

The United States, among the worst-performing developed nations on the environmental list, also happens to be the developed world's most unequal nation.

The new environmental rankings don't track the world's inequality rankings rung by rung, but that may be because researchers still lack, as they noted in their new report, all the “reliable data” they need.

It appears that social justice and environmental sustainability go hand in hand.