Aims to slow down global temperature rise by 0.5°C. The United States will lead a global campaign to reduce short-lived pollutants that aggravate global warming. In an announcement made on February 16, secretary of state Hillary Clinton announced the formation of a new coalition called Climate and Clean Air Coalition that will target non-Co2 pollutants, including methane, hydrofluorocarbons and black carbon. She made the announcement in the presence of ministers from four member countries of the coalition.

Methane leaks during production may offset climate benefits of natural gas.

Natural-gas operations could leak enough methane to tarnish their clean image. (Editorial)

Buses spew clouds of black exhaust fumes in Mexico City while, in India, wood burnt in rudimentary stoves fills houses with sooty smoke. Methane leaks from gas pipelines in Russia and rice paddies in China, eventually breaking down in sunlight and contributing to the production of smog and ozone. In each of these cases, simple steps to curb air pollution would promote public health; scaled up, they may offer the only realistic way to tame global warming over the next few decades.

Tropospheric ozone and black carbon (BC) contribute to both degraded air quality and global warming. We considered ~400 emission control measures to reduce these pollutants by using current technology and experience. We identified 14 measures targeting methane and BC emissions that reduce projected global mean warming ~0.5°C by 2050. This strategy avoids 0.7 to 4.7 million annual premature deaths from outdoor air pollution and increases annual crop yields by 30 to 135 million metric tons due to ozone reductions in 2030 and beyond.