Climate: Identifying Issues, Creating Solutions

The article “Global-Warming Warnings” first focuses on climate change and cites a National Climate Assessment & Development Advisory Committee draft report concluding “human-induced changes are already leading to damaging environmental shifts” (C&EN, Jan. 21, page 4). It notes, “The rapidity of greenhouse gas impacts will make projections and mitigation efforts increasingly difficult.”

The article then highlights a recent analysis by Tami C. Bond and coworkers concluding that the climate-warming capability of black carbon is double what was previously believed (J. Geophys. Res.: Atmos., DOI: 10.1002/jgrd.50171). The C&EN article concludes: “Diesel engines and household wood and coal burning would be the best black carbon sources to control to limit warming, Bond says.”

The unreported rest of the story is that research, development, and commercialization of advanced diesel technology in response to the Environmental Protection Agency’s stringent engine emission regulations is already providing a solution to reducing black carbon emissions. My colleagues and I have recently reviewed the revolutionary changes in diesel technology in the context of air pollution and health impacts (Regul. Toxicol. Pharmacol., DOI: 10.1016/j.yrtph.2012.04.005). Over the past two decades, EPA has issued increasingly stringent regulations limiting diesel engine emissions of particulate matter and other pollutants and mandated the use of ultra-low-sulfur fuel (<15 ppm sulfur).

A combination of improved engine technology, ultra-low-sulfur fuel (which enables use of catalysts in exhaust treatment), wall-flow diesel particulate filters, and selective catalytic reduction results in barely detectable emissions of black carbon and NO_xfrom diesel engines marketed today for on-road use. The hallmark carbon soot emissions of Rudolf Diesel’s traditional diesel engines have been controlled. The modeling results of Bond et al. indicate that controlling black carbon could be a “short-term, immediate action that we can take to slow climate change.” The technology is in hand and being used today. The question now is the pace of replacing old engines with new-technology diesel engines, which will be dominated by economic and regulatory considerations.

Scientists and scientific publications like C&EN need to emphasize the role of science in both identifying issues and providing solutions as illustrated by revolutionary changes in diesel technology to mitigate potential health impacts. Those same technological changes and reductions in black carbon emissions that improve air quality will, according to the calculations of Bond and coworkers, have near-immediate impact on global warming. This is a real success story that hopefully can be replicated with other energy technologies using carbon fuels.

Roger O. McClellan
Albuquerque, N.M.