1EMEP MSC-W, Norwegian Meteorological Institute, Oslo, Norway
2Dept. Earth & Space Sciences, Chalmers University of Technology, Gothenburg, Sweden
3Swedish Meteorological and Hydrological Institute, Norrköping, Sweden
4Department of Environmental Science, Aarhus University, 4000 Roskilde, Denmark
5National Institute for Public Health and the Environment (RIVM), Bilthoven, the Netherlands
6Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland
7University of Tromsø, 9037 Tromsø, Norway
Received: 28 Jan 2014 – Discussion started: 13 Mar 2014
Abstract. The impact of climate and emissions changes on the deposition of reactive nitrogen (Nr) over Europe was studied using four offline regional chemistry transport models (CTMs) driven by the same global projection of future climate over the period 2000–2050. Anthropogenic emissions for the years 2005 and 2050 were used for simulations of both present and future periods in order to isolate the impact of climate change, hemispheric boundary conditions and emissions, and to assess the robustness of the results across the different models.
Revised: 16 May 2014 – Accepted: 02 Jun 2014 – Published: 09 Jul 2014
The results from these four CTMs clearly show that the main driver of future N-deposition changes is the specified emission change. Under the specified emission scenario for 2050, emissions of oxidised nitrogen were reduced substantially, whereas emissions of NH3 increase to some extent, and these changes are largely reflected in the modelled concentrations and depositions. The lack of sulfur and oxidised nitrogen in the future atmosphere results in a much larger fraction of NHx being present in the form of gaseous ammonia.
Predictions for wet and total deposition were broadly consistent, although the three fine-scale models resolve European emission areas and changes better than the hemispheric-scale model. The biggest difference in the models is for predictions of individual N compounds. One model (EMEP) was used to explore changes in critical loads, also in conjunction with speculative climate-induced increases in NH3 emissions. These calculations suggest that the area of ecosystems that exceeds critical loads is reduced from 64% for year 2005 emissions levels to 50% for currently estimated 2050 levels. A possible climate-induced increase in NH3 emissions could worsen the situation, with areas exceeded increasing again to 57% (for a 30% NH3 emission increase).
Simpson, D., Andersson, C., Christensen, J. H., Engardt, M., Geels, C., Nyiri, A., Posch, M., Soares, J., Sofiev, M., Wind, P., and Langner, J.: Impacts of climate and emission changes on nitrogen deposition in Europe: a multi-model study, Atmos. Chem. Phys., 14, 6995-7017, doi:10.5194/acp-14-6995-2014, 2014.