Racing Up (and Down) the Performance Index Watching the rankings of countries by environmental performance over the last six years has been an occasion for admiration, mingled with bursts of skepticism and even disbelief. It is seldom a surprise that Scandinavian countries occupy at least four spots in the top 15, given their lauded environmental sensibilities (excepting, perhaps, Norwegian whalers and Danish fishermen). But it was always a surprise to someone who lived in the former Soviet Union that Russia, whose Communist forebears oversaw the dewatering of the Aral Sea, the emergence of pervasive air pollution in cities like Dniepopetrovsk and the Chernobyl nuclear disaster, ranked just a few notches below the United States - or in one case, above - in the 2006, 2008 and 2010 Yale and Columbia's Environmental Performance Index. So it is a relief to find that such counterintuitive findings are not repeated in the 2012 edition, which was released in tandem with the World Economic Forum's gathering in Davos, Switzerland, this week. Largely because of worsening air quality, Russia has plummeted in the rankings to 106th out of 132. And it came in dead last in a new analysis ranking countries by their environmental trajectory. Russia "has suffered a severe breakdown in environmental health as well as performance declines related to overfishing and forest loss," the report said. "It shows declines in every category except for slight improvements in sulfur dioxide emissions, though levels are still far below" the goals set for the countries being evaluated. At the other end of the scale, Switzerland and Latvia benefited from policies that have improved their air quality, benefiting people and ecosystems. The report's basic measurements are divided into two overall categories: environmental health and ecosystem vitality. Comparing countries at very different stages of development and with very different economic realities is obviously problematic, as the creators of the index acknowledge. "Economic development matters," the 2012 report notes. The environmental health scores, in particular, reveal a significant relationship with G.D.P. per capita, although there is a diversity of performance within every level of economic development. What is less intuitively understandable are some great leaps forward for some countries. Latvia, a tiny Baltic republic with a population of two million, jumped from No. 21 to No. 2 even though it scored high in only three of the 11 categories on which the overall score is based. Its strong suit was how its air quality is benefiting its ecosystems. Comparisons of rankings in previous years reveal a surprising amount of volatility in the top tier: only seven of those currently in the top 15 slots have consistently been in that elite company: Iceland, Switzerland, France, Costa Rica, Austria, Britain and New Zealand. New Zealand led the first index in 2006. And Canada, No. 8 on the pilot 2006 list, dropped to No. 46 in 2010 before rebounding to No. 37 this year - even though it ranked No. 1 in environmental health based on its air and water quality. It's hard to fathom how the rankings can change so sharply in the space of two years, given that environmental changes are often measured in decades. The United States has risen somewhat from its lowest rank - No. 61 in 2010 - and now ranks 49th, dragged down largely by the low score it gets for its approach to climate change. On that measure, it is in 121st place. It is not alone; "our analysis suggests that some issues are being successfully addressed at a worldwide scale, although performance on some other challenges, notably climate change, has declined globally," the authors write. The report shows that some of the most underperforming countries fall into regional groups, like those in Central Asia (Uzbekistan, Kazakhstan, Tajikistan, Turkmenistan and Mongolia), sub-Saharan Africa (including Congo, Nigeria and Cameroon) and southwestern Asia. Iraq, where air quality and water availability continued to decline, came in dead last, and Iran, Kuwait, Yemen and Pakistan, with their ever thirstier ecosystems, weren't far ahead. The individual scores of the countries can be found at a Web site hosted by Yale University. The report is prepared by the Yale Center for Environmental Law & Policy and Columbia's Center for International Earth Science Information Network. The two fastest-developing economies in the world ranked poorly, with India 125th out of 132 and China 116th. Both suffer from unhealthy air. It might come as a surprise to those familiar with the choking pollution around Beijing, which the government desperately tried to alleviate before the 2008 Olympic Games, that India's air quality ranks lowest, with China's a few notches above at No.