Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 15, 5501-5519, 2015
http://www.atmos-chem-phys.net/15/5501/2015/
doi:10.5194/acp-15-5501-2015
© Author(s) 2015. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
20 May 2015
Impacts of emission reductions on aerosol radiative effects
J.-P. Pietikäinen1, K. Kupiainen2,3, Z. Klimont2, R. Makkonen4, H. Korhonen1, R. Karinkanta1, A.-P. Hyvärinen1, N. Karvosenoja3, A. Laaksonen1, H. Lihavainen1, and V.-M. Kerminen4 1Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland
2International Institute for Applied Systems Analysis, Schlossplatz 1, 2361 Laxenburg, Austria
3Finnish Environment Institute SYKE, P.O. Box 140, 00251 Helsinki, Finland
4Department of Physics, University of Helsinki, P.O. Box 44, 00014 Helsinki, Finland
Abstract. The global aerosol–climate model ECHAM-HAMMOZ was used to investigate changes in the aerosol burden and aerosol radiative effects in the coming decades. Four different emissions scenarios were applied for 2030 (two of them applied also for 2020) and the results were compared against the reference year 2005. Two of the scenarios are based on current legislation reductions: one shows the maximum potential of reductions that can be achieved by technical measures, and the other is targeted to short-lived climate forcers (SLCFs). We have analyzed the results in terms of global means and additionally focused on eight subregions. Based on our results, aerosol burdens show an overall decreasing trend as they basically follow the changes in primary and precursor emissions. However, in some locations, such as India, the burdens could increase significantly. The declining emissions have an impact on the clear-sky direct aerosol effect (DRE), i.e. the cooling effect. The DRE could decrease globally 0.06–0.4 W m−2 by 2030 with some regional increases, for example, over India (up to 0.84 W m−2). The global changes in the DRE depend on the scenario and are smallest in the targeted SLCF simulation. The aerosol indirect radiative effect could decline 0.25–0.82 W m−2 by 2030. This decrease takes place mostly over the oceans, whereas the DRE changes are greatest over the continents. Our results show that targeted emission reduction measures can be a much better choice for the climate than overall high reductions globally. Our simulations also suggest that more than half of the near-future forcing change is due to the radiative effects associated with aerosol–cloud interactions.

Citation: Pietikäinen, J.-P., Kupiainen, K., Klimont, Z., Makkonen, R., Korhonen, H., Karinkanta, R., Hyvärinen, A.-P., Karvosenoja, N., Laaksonen, A., Lihavainen, H., and Kerminen, V.-M.: Impacts of emission reductions on aerosol radiative effects, Atmos. Chem. Phys., 15, 5501-5519, doi:10.5194/acp-15-5501-2015, 2015.
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The global aerosol--climate model ECHAM-HAMMOZ is used to study the aerosol burden and forcing changes in the coming decades. We show that aerosol burdens overall can have a decreasing trend leading to reductions in the direct aerosol effect being globally 0.06--0.4W/m2 by 2030, whereas the aerosol indirect radiative effect could decline 0.25--0.82W/m2. We also show that the targeted emission reduction measures can be a much better choice for the climate than overall high reductions globally.
The global aerosol--climate model ECHAM-HAMMOZ is used to study the aerosol burden and forcing...
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