Atmospheric input of nitrogen to the Baltic Sea basin : present situation, variability due to meteorology and impact of climate change

• We present estimates of the present and future deposition of atmospheric nitrogen into the Baltic Sea made using the Eulerian chemical transport model MATCH, and compare these with earlier model estimates. The average total nitrogen deposition for periods of five to ten years from 1992 to 2001 was estimated to be in the range of 261–300 Gg N yr–1.The deposition across the whole catchment area for 2001 was estimated to be 1.55–1.73 Tg N yr–1. Inter-annual variability of nitrogen deposition into the Baltic Sea was calculated to be in the range of 5.1%–8.0%. Investigating one climate change scenario using emissions for year 2000 indicated a rather small impact on total deposition of nitrogen due to climate change, i.e. increase of total nitrogen deposition by ~5% by the end of the 21st century as compared with present conditions. The combined effect of climate change and future changes in anthropogenic emissions of nitrogen to the atmosphere remains an open question. Additional climate change scenarios using different combinations of global and regional climate models and greenhouse gas emission scenarios need to be explored.

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NATURAL SCIENCES

NATURVETENSKAP

Applied Environmental Science

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