"While carbon dioxide may be the No. 1 contributor to rising global temperatures, scientists say, black carbon has emerged as an important No. 2, with recent studies estimating that it is responsible for 18 percent of the planet’s warming, compared with 40 percent for carbon dioxide. ...
"In Asia and Africa, cookstoves produce the bulk of black carbon, although it also emanates from diesel engines and coal plants there. In the United States and Europe, black carbon emissions have already been reduced significantly by filters and scrubbers. ... One recent study estimated that black carbon might account for as much as half of Arctic warming."
Where environmental problems are worst
The annual 2009 Index of Leading Environmental Indicators, issued today by Pacific Research Institute, a self-described free-market think tank, and the American Enterprise Institute, reports: "The world’s most severe environmental problems, as ranked by the Blacksmith Institute and Green Cross Switzerland, are overwhelmingly problems of poverty in developing nations. No American or Western European city ranks among the top 50 cities in the world for air pollution in a World Bank ranking."