Short-lived greenhouse gases that also contribute to air pollution are playing a major role in global warming. Black carbon alone is likely the second or third most important climate forcing agent. The short atmospheric lifetime of these pollutants means that, unlike CO2, reducing emissions produces a decrease in atmospheric concentration and a reduction of the radiative forcing that drives climate change. Black carbon and tropospheric ozone also have large negative effects at the regional and local level contributing substantially to indoor and urban air pollution and the formation of Atmospheric Brown Clouds that disrupt regional climate. Moreover, technologies to reduce emissions are available, cost-effective, and have already been widel...