Unger, N., D.T. Shindell, and J.S. Wang, 2009: Climate forcing by the on-road transportation and power generation sectors. Atmos. Environ. , 43, 3077-3085, doi:10.1016/j.atmosenv.2009.03.021.
The on-road transportation (ORT) and power generation (PG) sectors are major contributors to carbon dioxide (CO2) emissions and a host of short-lived radiatively-active air pollutants, including tropospheric ozone and fine aerosol particles, that exert complex influences on global climate. Effective mitigation of global climate change necessitates action in these sectors for which technology change options exist or are being developed. Most assessments of possible energy change options to date have neglected non-CO2 air pollutant impacts on radiative forcing (RF). In a multi-pollutant approach, we apply a global atmospheric composition-climate model to quantify the total RF from the global and United States (U.S.) ORT and PG sectors. ORT is a key target sector to mitigate global climate change because the net non-CO2 RF (dominated by ozone and black carbon) is positive and acts to enhance considerably the CO2 warming impacts. We perform further sensitivity studies to assess the RF impacts of a potential major technology shift that would reduce ORT emissions by 50% with the replacement energy supplied either by a clean zero-emissions source (S1) or by the PG sector, which results in an estimated 20% penalty increase in emissions from this sector (S2). We examine cases where the technology shift is applied globally and in the U.S. only. The total RF is negative in all cases for both S1 and S2 scenarios, global and U.S. emissions, and 20 and 100-year time horizons. The net non-CO2 RF is always important relative to the CO2 RF and outweighs the CO2 RF response in the S2 scenario for both time horizons. S1 offers additional improvements to ozone and black carbon air quality whereas S2 implies substantial degradation of sulfate air quality. Assessment of the full impacts of technology and policy strategies designed to mitigate global climate change must consider the climate effects of ozone and fine aerosol particles.
AU  - Wang, J. S.