Global and regional temperature-change potentials for near-term climate forcers
1Met Office Hadley Centre, FitzRoy Road, Exeter, Devon, EX1 3PB, UK
2Department of Environmental Sciences and Engineering, The University of North Carolina at Chapel Hill, 146B Rosenau Hall, CB #7431, Chapel Hill, North Carolina 27599, USA
3Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, 20740, USA
4Earth Science Directorate, NASA Goddard Space Flight Center, Greenbelt, Maryland, 20771, USA
5Center for International Climate and Environmental Research – Oslo (CICERO), P.O. Box 1129 Blindern, 0318 Oslo, Norway
6NASA Goddard Institute for Space Studies, 2880 Broadway, New York, New York, 10025 USA
*now at: Department of Meteorology, University of Reading, P.O. Box 243, Reading, RG6 6BB, UK
Abstract. We examine the climate effects of the emissions of near-term climate forcers (NTCFs) from 4 continental regions (East Asia, Europe, North America and South Asia) using results from the Task Force on Hemispheric Transport of Air Pollution Source-Receptor global chemical transport model simulations. We address 3 aerosol species (sulphate, particulate organic matter and black carbon) and 4 ozone precursors (methane, reactive nitrogen oxides (NOx), volatile organic compounds and carbon monoxide). We calculate the global climate metrics: global warming potentials (GWPs) and global temperature change potentials (GTPs). For the aerosols these metrics are simply time-dependent scalings of the equilibrium radiative forcings. The GTPs decrease more rapidly with time than the GWPs. The aerosol forcings and hence climate metrics have only a modest dependence on emission region. The metrics for ozone precursors include the effects on the methane lifetime. The impacts via methane are particularly important for the 20 yr GTPs. Emissions of NOx and VOCs from South Asia have GWPs and GTPs of higher magnitude than from the other Northern Hemisphere regions.
The analysis is further extended by examining the temperature-change impacts in 4 latitude bands, and calculating absolute regional temperature-change potentials (ARTPs). The latitudinal pattern of the temperature response does not directly follow the pattern of the diagnosed radiative forcing. We find that temperatures in the Arctic latitudes appear to be particularly sensitive to BC emissions from South Asia. The northern mid-latitude temperature response to northern mid-latitude emissions is approximately twice as large as the global average response for aerosol emission, and about 20–30% larger than the global average for methane, VOC and CO emissions.