Issue Date: November 2, 2009
Taking into account the interactions between greenhouse gases and aerosol pollutants in the atmosphere substantially increases the impact of some greenhouse gas emissions in computer simulations used to assess global warming and climate change (Science 2009, 326, 716). The observation will place an even heavier burden on policymakers as they make critical choices on how to mitigate atmospheric pollution and control greenhouse gas emissions at the same time.
Climate scientists know that most aerosols exert a cooling influence on climate, but researchers have had difficulties in adequately accounting for interactions between greenhouse gases and aerosols in climate models.
Drew T. Shindell and colleagues at NASA’s Goddard Institute for Space Studies at Columbia University found that atmospheric compounds such as methane alter the abundance of hydroxyl radicals and other oxidants that convert sulfur dioxide, a pollutant from burning fossil fuels, to sulfate aerosols.
In the case of methane, the second most important greenhouse gas behind carbon dioxide, considering its interactions with aerosols results in a 20–40% greater global warming potential, Shindell says. Thus, choosing to control sulfur dioxide emissions without controlling methane emissions along with carbon dioxide emissions could inadvertently increase global warming.
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