Global Climate Forcing by Criteria Air Pollutants

Ambient air pollution has significant impacts on global climate change in complex ways, involving both warming and cooling, and causes an estimated one million deaths every year. Modeling studies and observations from a suite of platforms, including those that are space based, have revealed that air pollution is a widespread global phenomenon. The net effect of air pollution is a global cooling that is masking 50% of the committed greenhouse gas (GHG) warming from the Industrial Revolution. Aggressive air pollution abatement and climate stabilization strategies that reduce cooling pollutants may lead to a short-term warming surge that is unsafe for ecosystems and the human population, imposing complex trade-offs in policy making. Conversely, selective reduction of warming air pollutants to mitigate near-term climate change may offer opportunities for synergistic policy development. Reducing and preventing the accumulation of fossil-fuel carbon dioxide (CO2) in the atmosphere is the only sustainable way to protect climate safety in the long term. Here, the current understanding of air pollution effects on global climate change is reviewed, including assessment by individual pollutant, precursor emission, economic sector, and policy-relevant scenarios.