An Uncertain Future for the Climate and Health Impacts of Anthropogenic Aerosols in Africa
JOE ADABOUK AMOOLI, Marianne T. Lund, Bjørn H. Samset, Sourangsu Chowdhury, Gunnar Myhre, Anne N. Johansen, Daniel Westervelt, Columbia University/Lamont-Doherty Earth Observatory
Abstract Number: 247
Working Group: Aerosol Processes and Properties in Changing Environments in the Anthropocene
Abstract
Limited data availability and distinct regional characteristics of sources lead to a wide range of future aerosol emissions projections for Africa. Here we quantify and explore the implications of this spread for climate and health impact assessments. Using the Evaluating the Climate and Air Quality Impacts of Short-Lived Pollutants (ECLIPSE), the Shared Socioeconomic Pathways (SSPs), and the United Nations Environment Programme (UNEP) emission projections, we find high scenario diversity and regional heterogeneity in projected air pollution emissions across Africa. Baseline emissions also vary in their sectoral split. Using 10 different emissions pathways as input to the Oslo chemical transport model version 3 (OsloCTM3), we find that regionally-averaged annual-mean population-weighted PM2.5 concentrations exhibit divergent trends depending on scenario stringency, with Eastern Africa PM2.5 concentrations increasing by up to 6 µg m-3 (37 %, SD ± 2.7 µg m-3) by 2050 under the UNEP Baseline, SSP370, and ECLIPSE current legislation scenarios. In almost all cases, excess deaths increase substantially, with increases of up to more than 2.5 times compared to the baseline. We also find a net positive aerosol-induced radiative forcing across Africa in all scenarios by 2050 except two high-sulfur emission UNEP scenarios, with values ranging from 0.03 W m-2 in SSP119 to 0.27 W m-2 in SSP585. The wide-spread in projected emissions and differences in sectoral distributions across scenarios highlights the critical need for accurate activity data and harmonization efforts in preparation for upcoming assessments such as the 7th Assessment Report of the Intergovernmental Panel on Climate Change.