Abstract
Abstract. Emissions of most land-based air pollutants in western Europe have decreased in the last decades. Over the same period emissions from shipping have also decreased, but with large differences depending on species and sea area. At sea, sulfur emissions in the SECAs (Sulphur Emission Control Areas) have decreased following the implementation of a 0.1 % limit on sulfur in marine fuels from 2015. In Europe the North Sea and the Baltic Sea are designated as SECAs by the International Maritime Organisation (IMO). Model calculations assuming present (2016) and future (2030) emissions have been made with the regional-scale EMEP model covering Europe and the sea areas surrounding Europe, including the North Atlantic east of 30∘ W. The main focus in this paper is on the effects of ship emissions from the Baltic Sea. To reduce the influence of meteorological variability, all model calculations are presented as averages for 3 meteorological years (2014, 2015, 2016). For the Baltic Sea, model calculations have also been made with higher sulfur emissions representative of year 2014 emissions. From Baltic Sea shipping the largest effects are calculated for NO2 in air, accounting for more than 50 % of the NO2 concentrations in central parts of the Baltic Sea. In coastal zones contributions to NO2 and also nitrogen depositions can be of the order of 20 % in some regions. Smaller effects, up to 5 %–10 %, are also seen for PM2.5 in coastal zones close to the main shipping lanes. Country-averaged contributions from ships are small for large countries that extend far inland like Germany and Poland, and larger for smaller countries like Denmark and the Baltic states Estonia, Latvia, and Lithuania, where ship emissions are among the largest contributors to concentrations and depositions of anthropogenic origin. Following the implementations of stricter SECA regulations, sulfur emissions from Baltic Sea shipping now have virtually no effects on PM2.5 concentrations and sulfur depositions in the Baltic Sea region. Adding to the expected reductions in air pollutants and depositions following the projected reductions in European emissions, we expect that the contributions from Baltic Sea shipping to NO2 and PM2.5 concentrations, and to depositions of nitrogen, will be reduced by 40 %–50 % from 2016 to 2030 mainly as a result of the Baltic Sea being defined as a Nitrogen Emission Control Area from 2021. In most parts of the Baltic Sea region ozone levels are expected to decrease from 2016 to 2030. For the Baltic Sea shipping, titration, mainly in winter, and production, mainly in summer, partially compensate. As a result the effects of Baltic Sea shipping on ozone are similar in 2016 and 2030.
Highlights
Even though emissions of most air pollutants have decreased in the countries surrounding the Baltic Sea (BAS) in past decades (Tista et al, 2018), air pollution and atmospheric depositions affecting ecosystems remain a problem in the region
Our calculations clearly show that, following the stricter SECA regulations from 1 January 2015, sulfur emissions from BAS shipping contribute little to depositions of oxidised sulfur and PM2.5 concentrations in air
This is in contrast to pre-2015 conditions when less stringent sulfur regulations were in place, and even more compared to pre-2011 conditions when up to 1.5 % in sulfur was allowed in marine fuels in the SECAs
Summary
Even though emissions of most air pollutants have decreased in the countries surrounding the Baltic Sea (BAS) in past decades (Tista et al, 2018), air pollution and atmospheric depositions affecting ecosystems remain a problem in the region. In a global model calculation Jonson et al (2018) found that a large portion of the anthropogenic contributions to air pollution and nitrogen depositions in adjacent countries could be attributed to NOS and BAS ship emissions of NOx and particles after the introduction of stricter SECA regulations in 2015. Claremar et al (2017) calculated the dispersion of air pollutants and depositions from NOS and BAS shipping for the period 2011 to 2050, with the main focus on seawater acidity in BAS They found that, in the future, ship emissions could remain a major source of acidity, in particular when assuming high penetration of open-loop scrubbers in combination with the use of high-sulfur-content fuels. Model calculations have been made with future (2030) landbased and ship emissions
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