Confronting the role of non-CO2 pollutants in global warming
U.S. EPA
limiting global warming, Michael San Diego noted in a prepared stateAggressively reducing emissions MacCracken of the Climate Institute ment. “We have to take advantage of of non-CO2 climate drivers could noted in a recent paper. Also critical the proven ability of this legally bindforestall abrupt climate change are their atmospheric lifetimes, ing treaty to quickly phase down for up to 40 years, according to which range from centuries to milHFCs.” North American leaders rea recent study in the Proceedings lennia for CO2 and HFCs and from cently submitted a proposal to start of the National Academy of Scithis process for consideration at the ences (2009, DOI 10.1073/ days to weeks for black carbon. MP annual meeting in November. pnas.0902568106). Without such “Steep, immediate reductions in soot efforts, even drastic cuts to would eliminate its warmCO2 emissions will fail to ing influence over the entire 21st century,” he put the brakes on planexplains. Similarly, swift etary warming soon cutbacks in emissions of enough to avoid climate methane and ozone-protipping points, the authors ducing pollutants would warn. yield sharp and enduring Hydrofluorocarbons declines in their warming (HFCs), black carbon influence. (soot), ground-level ozone, Because much of the and methane together repnon-CO2 pollution origiresent an estimated 40-50% of the warming nates in developing councaused by human activitries, those nations can ties. “We’re on track for a 2 play a substantial role in Industrial air pollution produces tropospheric ozone, which is °C warming that will put combating climate change, us in the danger zone, and toxic to crops as well as humans. Tropospheric ozone has MacCracken stresses. “We increased by about 30% since the preindustrial era, and its current research shows it’s don’t want climate negotiaestimated contribution to global warming is 20% that of CO2. coming faster than anticitions to fail because we pated,” says study coauthor DurSoot now ranks as the second or can’t get agreement on everyone cutwood Zaelke of the Institute for third biggest contributor to climate ting CO2 emissions immediately. DeGovernance and Sustainable Develchange. However, soot’s short life veloping nations can do a lot to opment. “Restricting CO2 emissions span offers opportunities for comoffset their ongoing CO2 output by paratively quick fixesssuch as is absolutely critical, but it won’t be going after these other pollutantssat particulate filters for vehicles and enough. So the question is how the same time improving public clean-burning or solar-powered quickly we can deliver cooling on the health and energy efficiency. This stovessthat could yield significant non-CO2 side.” would allow for their continued declimate savings, the authors say. velopment, while cost-effective, cliImplementing “fast-action” mitigaLikewise, the means for slashing levmate-friendly energy technologies tion strategies based on available els of ozone precursors such as carevolve, and demonstrate the necestechnologies would jump-start this bon monoxide and nitrogen oxides sary commitment from all nations effort, the researchers say. One key are within reach. Research shows while recognizing the equity imbalstep would be to phase down the that rigorous enforcement of air-polance created by very different per production and use of HFCs, which lution technologies and regulations capita emissions.” are now known to act as long-lasting could cut these emissions by more The study is intended as a call greenhouse gases. Use of HFCs has than half, dramatically decreasing to action, Zaelke says. “Speed been growing because of the rising tropospheric ozone. “We know how matters. We have to move fordemand for air-conditioning and to curb air pollution; we just need to ward on all fronts now, using exrefrigeration in developing countries. do it better and faster, and get the isting governance structures, Current projections indicate that by solutions applied in developing without waiting for a climate mid-century the impact of HFCs on countries. We can borrow from and treaty to get started. We need opthe climate could be approximately utilize working international agreetimism and energy to solve this 20% of that from CO2 emissions, if ments to do this,” Zaelke problem, and these fast-action the current trends continue unemphasizes. strategies can help provide more abated. “The Montreal Protocol (MP) Comparing the overall greenhouse confidence that we can do it.” has already delayed climate change contributions of climate drivers reby 7-12 years,” lead author Mario —NOREEN PARKS veals only part of their potential for Molina of the University of California 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / January 1, 2010
10.1021/es903289a
2010 American Chemical Society
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Published on Web 11/18/2009
