The affecting dance of gas and aerosol

The actual effects of gas emissions on the Earth’s atmosphere are significantly different from those predicted by the Kyoto Protocol and the Intergovernmental Panel on Climate Change, researchers report in the Oct. 29 issue of Science. This new finding, which was revealed after the complex chemical interactions between atmospheric gases and aerosols were taken into account, should help researchers revise and optimize strategies for slowing global warming by reducing certain gas emissions from human sources. Drew Shindell and colleagues used a computer simulation that couples atmospheric composition and climate together and found that interactions between gases and aerosols can significantly alter the accumulation of those gases in the atmosphere. The researchers found that methane, in particular, has a greater impact on the atmosphere than carbon-trading schemes and global policies currently acknowledge, when one stops to consider methane’s interactions with aerosols. In light of these new results, the authors suggest that future policies regarding gas emissions and global warming should take gas-aerosol interactions into consideration as well.

Two related Perspectives also examine the complex relationships between air pollution and climate change. First, David Parrish and Tong Zhu discuss the opportunities that mega-cities (urban centers with populations exceeding 10 million) present to slowing the current rate of climate change around the world. They highlight how optimum air quality and climate change policies could be effectively implemented in such areas of high population density. Then, Almut Arneth and colleagues discuss the enigmatic relationship between air quality and climate change—and whether air pollution controls will, in fact, accelerate or mitigate global climate change.

Article #12: "Improved Attribution of Climate Forcing to Emissions," by D.T. Shindell; G. Faluvegi; D.M. Koch; G.A. Schmidt; N. Unger; S.E. Bauer at Columbia University in New York, NY; D.T. Shindell; G. Faluvegi; D.M. Koch; G.A. Schmidt; N. Unger; S.E. Bauer at NASA Goddard Institute for Space Studies in New York, NY.