Regional temperature change potentials for short lived climate forcers from multiple models
Borgar Aamaas1, Terje K. Berntsen1,2, Jan S. Fuglestvedt1, Keith P. Shine3, and William J. Collins31CICERO Center for International Climate Research, PB 1129 Blindern, 0318 Oslo, Norway 2Department of Geosciences, University of Oslo, Norway 3Department of Meteorology, University of Reading, Reading RG6 6BB, UK
Received: 14 Feb 2017 – Accepted for review: 13 Mar 2017 – Discussion started: 14 Mar 2017
Abstract. We calculate the absolute regional temperature change potential (ARTP) of various short lived climate forcers (SLCFs) based on detailed radiative forcing (RF) calculations from four different models. The temperature response has been estimated for four latitude bands (90–28° S, 28° S–28° N, 28–60° N, and 60–90° N). The regional pattern in climate response not only depends on the relationship between RF and surface temperature, but also on where and when emissions occurred and atmospheric transport, chemistry, interaction with clouds, and deposition. We present four emissions cases covering Europe, East Asia, the global shipping sector, and the globe. Our study is the first to estimate ARTP values for emissions during Northern Hemisphere summer (May–October) and winter season (November–April). The species studied are aerosols and aerosol precursors (black carbon (BC), organic carbon (OC), SO2, NH3), ozone precursors (NOx, CO, volatile organic compound (VOC)), and methane (CH4). For the response to BC in the Arctic, we take into account the vertical structure of the RF in the atmosphere, and an enhanced climate efficacy for BC deposition on snow. Of all SLCFs, BC is the most sensitive to where and when the emissions occur, as well as giving the largest difference in response between the latitude bands. The temperature response in the Arctic is almost 4 times larger and more than 2 times larger than the global average for Northern Hemisphere winter emissions for Europe and East Asia, respectively. The latitudinal breakdown gives likely a better estimate of the global temperature response as it accounts for varying efficacies with latitude. An annual pulse of non-methane SLCFs emissions globally (representative of 2008) leads to a global cooling. Whereas, winter emissions in Europe and East Asia give a net warming in the Arctic due to significant warming from BC deposition on snow.
Aamaas, B., Berntsen, T. K., Fuglestvedt, J. S., Shine, K. P., and Collins, W. J.: Regional temperature change potentials for short lived climate forcers from multiple models, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-141, in review, 2017.