RESEARCH ARTICLE
Assessing the costs and environmental benefits of IMO regulations
of ship-originated SOx and NOx emissions in the Baltic Sea
Sari Repka , Anne Erkkila¨-Va¨lima¨ki, Jan Eiof Jonson,
Maximilian Posch, Janne To¨rro¨nen, Jukka Pekka Jalkanen
Received: 25 February 2020 / Revised: 8 September 2020 / Accepted: 5 January 2021 / Published online: 7 March 2021
Abstract To assess the value of the environmental benefits
of the Sulphur Emission regulation (SECA) that came into
force in 2015, changes in depositions of SOx and NOx
from ship exhaust gas emissions were modelled and
monetized for the Baltic Sea region for the years 2014
and 2016. During this period, the total deposition of SOx in
the study area decreased by 7.3%. The decrease in ship-
originated SOx deposition from 38 kt to 3.4 kt (by over
88%) was translated into a monetary value for the
ecosystem impacts of nearly 130 million USD, according
to the EcoValue08 model. This is less than the modelled
health benefits, but it is not insignificant. For NOx, there
was no decreasing trend. The exceedance of the critical
loads of SOx and NOx was also estimated. The effect of
Baltic shipping on the exceedance of critical loads of
acidification after SECA is very small, but Baltic shipping
still has a considerable effect on the exceedance of critical
loads for eutrophication.
Keywords Atmospheric deposition  Baltic Sea 
Maritime traffic  Monetary valuation  NOx  SOx
INTRODUCTION
In the Baltic Sea region (BSR), environmental degradation,
such as acidification and eutrophication, has caused sci-
entific and public concerns. In Europe, the emissions of key
atmospheric pollutants have decreased steadily over the
past decades (see EMEP 2018) due to the tightening of
regulations on land-based sources. However, the Baltic Sea
is one of the most heavily trafficked sea areas, and lately
regulatory decisions to reduce airborne emissions from
ships have been made (HELCOM 2018).
In January 2015, in accordance with the revised MAR-
POL Annex VI, the sulphur content of bunker fuel was not
allowed to exceed 0.1% in the SECA (IMO 2008). Fuels
with a higher sulphur content may also be used in combi-
nation with emission reduction technology that reduces the
sulphur emission to levels corresponding to the use of low
sulphur fuels. The Baltic Sea and the North Sea are also
designated as NECAs (NOx Emission Control Areas). In
NECAs, the aim is to reduce NOx emissions from shipping
by 80% by using a three-tier system from January 2021
onwards (IMO 2017). TIER 1 came into force in 2005, and
TIER 2 in 2011 with approximately a 20% reduction in
NOx emissions from shipping compared with TIER 1
(IMO 2008). These two emission standards apply globally.
The more stringent TIER 3, which came into force in 2016,
requires an approximately 80% reduction in NOx emis-
sions from TIER 1. Only gradual reductions of NOx
emissions are expected as the NECA regulations only
apply to new ships or major modifications of existing ships.
The depositions of SOx and NOx from the Baltic Sea
shipping prior to and after the SECA regulation have been
modelled with an atmospheric dispersion model (EMEP
model; see Jonson et al. 2019). There were significant
reductions in the SOx deposition, but there was no
decreasing trend for NOx (Jonson et al. 2019). Approxi-
mately 15% of the NOx deposition in certain countries still
originate from shipping (Jonson et al. 2019).
The abatement costs for the shipping industry were
heatedly debated before the 2015 SECA regulation. It was
estimated prior to the regulation that the health benefits of
SECA regulation would exceed the costs (reviewed in
EMSA 2010). To support planning and decision making,
the cost efficiency of environmental regulations should also
be estimated after the regulation comes into force. (Kalli
123
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Ambio 2021, 50:1718–1730
https://doi.org/10.1007/s13280-021-01500-6
et al. 2013; La¨hteenma¨ki-Uutela et al. 2017; A˚stro¨m et al.
(2018).
Impacts on human health are of great interest in cost-
benefit analyses (Im et al. 2018). In the case of the SECA,
they have been evaluated both prior to the regulation
(EMSA 2010) and after the regulation came into force
(Barrega˚rd et al. 2019). In comparison, the benefits related
to environmental improvements, such as the reduction of
eutrophication and acidification, are not discussed as much
(Ahlroth 2014) and in the case of SECA not evaluated in
previous studies.
In this paper, we focus on the monetary valuation of
changes in acidification and eutrophication by applying
values that are available from the literature (Turner et al.
2004; Ahlroth 2014; Pizzol et al. 2015), as the monetisation
of the environmental benefits of SECA regulation has not
been done. Monetary valuation methods are controversial
but useful as they provide more quantitative information
than non-monetary methods by enabling easily under-
standable and comparable estimates of the costs of policy
actions (Ahlroth 2014; Pizzol et al. 2015, 2017).
Critical load exceedance is another way of analysing the
environmental effects of pollutants spatially on different
scales. A critical load (CL) is defined as ‘‘a quantitative
estimate of an exposure to one or more pollutants below
which significant harmful effects on specified sensitive
elements of the environment do not occur according to
present knowledge’’ (Nilsson and Grennfelt 1988). CLs are
calculated for terrestrial ecosystems and aquatic ecosys-
tems, and a ‘sensitive element’ can be any part of an
ecosystem, e.g. fine roots in forest soils or fish in a lake.
We will analyse the effects of shipping on the exceedance
of critical loads in the BSR before and after the 2015 SECA
regulation. Critical loads (CLs) were originally derived in
the context of acidification and are the limits for sulphur
and nitrogen deposition, called CLs of acidity (CLaci).
Later, limits for the eutrophying effect of N deposition
have also been derived, i.e. CLs for eutrophication
(CLeutN, also called CL of nutrient N).
MATERIALS AND METHODS
Modelling of SOx and NOx deposition
Atmospheric depositions of SOx and NOx have been cal-
culated with the EMEP model rv4.14 with resolution of
0.1 9 0.1 as explained in Jonson et al. (2019). A detailed
model description is available in Simpson et al. (2012).
Model updates are described in Simpson et al. (2018) and
references therein. All model runs have been made for
three meteorological years: 2014, 2015, and 2016. In order
to smooth meteorological variability, all the results
presented here are based on the averages for these three
meteorological years. Land-based anthropogenic emissions
are from Eclipse version 5a (ECLIPSE V5 2014).
The evaluation of the exhaust emissions of marine traffic
was based on the messages provided by the Automatic
Identification System (AIS), which enables the identifica-
tion and location determination of ships. The emissions are
computed based on the relationship of the instantaneous
speed to the design speed and technical information of the
engines of the ships with a Ship Traffic Emission Assess-
ment Model (Jalkanen et al. 2009). For the Baltic Sea, ship
emissions for 2014 (pre 0.1% SECA) and 2016 (0.1%
SECA) are used in the EMEP model calculations. For the
remaining sea areas, ship emissions for the year 2015 are
used, see Johansson et al. (2017). As the EMEP calcula-
tions are made for several meteorological years, monthly
averaged emissions are used in this study.
Spatial and temporal distribution of SOx and NOx
deposition
The study area consists of the Baltic Sea and the riparian
countries together with Norway (Fig. 1). The modelled
deposition data of SOx and NOx include wet and dry
deposition due to land and sea (ship) emission sources for
the years 2014 and 2016. Depositions and spatial distri-
bution maps were prepared using ESRI’s ArcMap 10.5.1.
programme (ESRI 2017) in NetCDF format. The EMEP
model datasets were in NetCDF format and covered an area
between 30o W, 45 E and between 30 and 75 N. The
datasets were first converted into raster layers for ArcMap
analyses. The ArcMap Zonal Statistics tool was used to
create a table of the SOx and NOx deposition data values
for the entire sea area of the Baltic Sea as one entity and for
each riparian country, respectively (ESRI 2017). The total
depositions of SOx and NOx for each country and for the
sea area were calculated by multiplying the average
deposition calculated with field calculator for the zone in
question (mg/m2) by the zone’s total area (m2).
Critical loads of acidification and eutrophication
Methods to compute CLs are summarised in Posch et al.
(2015). Critical loads are calculated for terrestrial ecosys-
tems (mostly forests) and for lakes and streams, but no
methodology has been established to derive CLs for marine
ecosystems. Critical loads are collected under the Con-
vention on Long-range Transboundary Air Pollution
(CLRTAP), hosted by the United Nations Economic
Commission for Europe (UNECE, www.unece.org/env/
lrtap), and used to support European assessments and
negotiations on emission reductions (Reis et al. 2012; EEA
2014; De Vries et al. 2015; Maas and Grennfelt 2016).
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If a deposition is higher than the CL at a site, the CL is
said to be exceeded. For CLeutN, the exceedance is the
difference between total deposition of N and CLeutN (set
to zero, if negative). For acidity, the exceedance is a well-
defined distance measure from the critical load function
(see Posch et al. 2015). To obtain a single exceedance
number for a grid cell (or any other region), the so-called
average accumulated exceedance (AAE) is used, defined as
the weighted mean of the exceedances of all ecosystems
within the grid cell, with the weights being the respective
ecosystem areas (Posch et al. 2015). The current European
CL database for acidity and eutrophication CLs was used
(Hettelingh et al. 2017).
Model calculations for all three meteorological years
were made for the following five scenarios:
‘Base 2016’: All emissions from 2016/2015
‘No Balt’: No Baltic Sea ship emissions, elsewhere
2016/2015 emissions
‘Balt 2014’: 2014 Baltic Sea ship emissions, elsewhere
2016/2015 emissions
‘Baltic Sea 2030’: 2030 Business-As-Usual (BAU)
emissions.
‘No Balt 2030’: No Baltic Sea ship emissions, elsewhere
BAU 2030 emissions
Monetary valuation
To evaluate the economic effects of SECA in the BSR,
monetisation models for atmospheric pollution were
reviewed from the literature. In many cases, the monetary
values are based on the surveys of individuals’ willingness
to pay for environmental quality, while some are based on
the prevention or restoration costs (e.g. Ahlroth 2014,
Pizzol et al. 2015). Economic modelling requires a number
of simplifying assumptions and value choices depending on
the scope, societal context, and geographical area that the
models are made for (Turner et al. 2004; Ahlroth 2014;
Pizzol et al. 2015). Results may not be statistically robust
due to small sampling size or weights may be based on the
old models (Turner et al. 2004). Therefore, the results of
Fig. 1 The areas of the riparian states and the Baltic Sea use in the calculations. The area of EMEP datasets covers larger area between 30 W,
45 E and between 30 and 75 N (approximately the area of the upper left corner map). The area of the Russian side (4 Mkm2) is presented in the
smaller box of the upper left corner map. Geographic Coordinate System is World Geodetic System of 1984 (GCS WGS 1984)
123
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1720 Ambio 2021, 50:1718–1730
different weighting factors should be used bearing in mind
that the results are more indicative than absolute values
(Ahlroth 2014; Nguyen et al. 2016).
According to Turner et al. (2004), the receptors of
environmental impacts of air pollution include the cate-
gories of buildings, agriculture and ecosystems, as well as
climate change. There are relatively few studies on costs
for environmental impacts compared to human health
effects, and they mostly originate from 1990s and 2000s.
However, the weighting sets do not always cover all the
environmental impacts, e.g. the impacts of acidification
(Ahlroth and Finnveden 2011). We applied values of sul-
phur and nitrogen from three weighting sets, i.e. STEP-
WISE2006, Ecovalue08 and Eco-cost/Value Ratio (EVR),
and from the review of Turner et al. (2004) summing
several values of external costs and benefits of waste
management to one mean value (see Table 1; Turner et al.
2004; Weidema 2009; Ahlroth & Finnveden 2011; Vogt-
la¨nder & Bijma 2000). The weighting factors have been
calculated for atmospheric emissions, but we apply them to
depositions, assuming that the direct environmental
impacts to ecosystems, agriculture and buildings are mostly
generated in the deposition processes.
We assumed that both sulphate and SO2 used in the
valuation by and large indicate the environmental impacts
of sulphur. STEPWISE2006 also includes values for
ecosystem effects of SO2, which we applied here (Wei-
dema 2009; Table 1, Pizzol et al. 2015). Furthermore, we
used the mean values of the impact on agriculture and
buildings from the summary of values of key pollutants
compiled by Turner et al. (2004) from 10 previous studies.
Ecovalue08 was developed for the Swedish environment
and adapted for Scandinavia (Ahlroth and Finnveden
2011), and thus, it is a geographically fitting set for the sea
area and riparian countries of the BSR. The highest values
for SO2 in terms of prevention of acidification are produced
by the Eco-Cost/Value ratio (EVR) (Vogtla¨nder and Bijma
2000; Vogtla¨nder et al. 2001). EVR is based on abatement
costs. We used these models to estimate the damage in
monetary values of ship-originated sulphur deposition on
the sea area of the Baltic Sea and its riparian countries.
Values for NOx monetisation are available from
STEPWISE2006, and the summary values are compiled by
Turner et al. (2004). NOx values for different impact cat-
egories were summed to one single value representing the
monetary value of NOx deposition. The calculation of the
monetary values of SOx and NOx deposition from Baltic
Sea shipping was done by multiplying the deposition of
SOx and NOx with the monetary values. The monetary
values were inflation adjusted, according to the currency of
April 2018 and then converted to US dollars (USD).
The results of depositions of SOx and NOx from Baltic
shipping to the sea area and riparian countries are also
discussed in Jonson et al. (2019). In our study, we have
used the same data as basis for the monetisation and critical
load exceedance calculations. The monetisation models
Table 1 Monetary values of the environmental impacts of SOx and NOx. Letters refer to the calculations of the monetary values in Tables 6 and
7. The values provided by Turner et al. (2004) are compared with Stepwise2006 by Weidema (2009) using the exchange rate of 1.45 EUR/GBP
in 2003. The same EUR/GBP exchange rate is used for all values of Turner et al. (2004). Inflation is calculated to April 2018 and converted to
USD using the April 16th 2018 currency rate of 1 EUR = 1.237 USD
Substance Impact categories
(source in brackets)
References Monetary values of
environmental impacts
Monetary values
of environmental
impacts USD2018 kt
-1
Reference to
Tables 6 and 7
SO2 Ecosystem impacts (1) Weidema 2009 150 EUR2003 t
-1 235 550 A
SO2 Impacts on agriculture (2)
Impacts on buildings (2)
Ecosystem impacts (2)
TOTAL OF SO2 impacts
(2)Turner et al. 2004,
Weidema 2009
20
838
12
870 EUR2003 t
-1
1 366 198 B
SO2 Acidification (3) (3) Ahlroth &
Finnveden 2011
30 SEK2010 Kg
-1 3 864 900 C
SOx equivalent Prevention of acidification (4) (4) Vogtla¨nder &
Bijma 2000
6.40 EUR1999 Kg
-1 10 968 011 D
NOx Ecosystem impacts (1)
Agricultural impacts via
photochemical ozone (1)
Impacts on buildings (2)
Fertilisation effects (2)
TOTAL OF NOx impacts
600
400
300
Benefit of 200
1 100 EUR2003 t
-1
1 727 376 E
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include all the impact categories of acidification and
eutrophication, thus, also the effects of the exceedance of
critical loads.
RESULTS
Depositions of SOx and NOx from shipping
SOx deposition originating from the Baltic Sea shipping
was 2.2% of the total deposition in the study area in 2014.
In 2016, the share of ship-originated SOx deposition had
decreased to 0.3% (Table 2, Jonson et al. 2019). The share
of the ship-originated SOx differed between countries due
to factors such as proximity to shipping lanes and ports, as
well as meteorological factors. For example, Russia
received 61% of the total SOx deposition in the study area,
but only 22% of the ship-originated SOx deposition fell on
Russia. The share of the ship-originated SOx deposition
was 0.8% in Russia, and in Poland, it was even less, 0.6%.
The highest shares of ship-originated SOx were in Den-
mark and Estonia, approximately 7%. In 2016, the relative
proportions of ship-originated SOx deposition remained
rather similar for most of the countries, probably also due
to the averaged meteorology that was applied in modelling.
The Baltic Sea itself received 44–45% of the ship-
originated SOx deposition both in 2014 and 2016. It was
15% of the total deposition of SOx in 2014 and 2.3% in
2016 (Table 2). The total deposition of SOx decreased by
approximately 21% in the sea areas, which was more than
in the riparian countries. Indeed, the spatial pattern of the
ship-originated SOx deposition followed the patterns of the
most heavily trafficked shipping lanes (Jonson et al. 2019).
The SOx deposition was considerably larger in 2014 than
in 2016, reaching far into the land areas (Jonson et al.
2019).
The current contribution of Baltic Sea shipping to the
total deposition of sulphur in the BSR is very low. In 2016,
the model calculations show that the total sulphur deposi-
tion from Baltic Sea shipping in the study area decreased
by 7.3% due to the regulations. The share of the ship-
originated SOx deposition decreased by over 88%. In all
the countries in the study area, the SOx deposition from the
Baltic Sea shipping decreased by over 85% and in Poland
by over 97% (Table 2).
The total NOx deposition was almost the same in 2014
and 2016 (Jonson et al. 2019, Table 3), and the ship-orig-
inated NOx deposition was 2.6% of the total deposition in
both years. In Lithuania and Norway, the amount of NOx
depositions from the Baltic Sea shipping increased slightly.
In Finland, Estonia, Sweden, and the Baltic Sea, the share
of ship-originated NOx of the total deposition was the
highest, approximately 7–9%. The lowest depositions were
in Germany, Poland, and Russia, approximately 0.5–2%.
The spatial patterns of the ship-originated NOx deposi-
tion were rather similar in 2014 and 2016 (Jonson et al.
Table 2 Atmospheric deposition of sulphur in the study area in 2014 and 2016, respectively, calculated using the average meteorology of the
years 2014–2016. TOT is the total of dry and wet depositions. Depositions from Baltic Sea shipping are included in TOT, but the individual
contributions are also shown separately as SHIP. SHIP/TOT is the share of the ship-originated SOx deposition of the total deposition. *European
side of Russia. **The sea areas of the Baltic Sea
SOx deposition in 2014 SOx deposition in 2016 CHANGE of SOx deposition from 2014
to 2016
Country TOT kt TOT % SHIP
kt
SHIP
%
SHIP/
TOT
TOT kt TOT
%
SHIP
kt
SHIP % SHIP/
TOT
TOT kt TOT
%
SHIP kt SHIP
%
Denmark 12 902 0.7 982 2.6 7.6 10 802 0.7 99 2.3 0.9 - 21 - 16.3 - 883 - 89.9
Estonia 10 841 0.6 776 2.0 7.2 9344 0.6 84 1.9 0.9 - 1497 - 13.8 - 692 - 89.2
Finland 47 501 2.7 2666 7.0 5.6 42 455 2.6 293 6.7 0.7 - 5046 - 10.6 - 2373 - 89.0
Germany 139 157 7.9 125 3.3 0.9 129 152 8.0 148 3.4 0.1 - 10 005 - 7.2 - 1102 - 88.2
Latvia 17 046 1.0 771 2.0 4.5 14 968 0.9 93 2.1 0.6 - 2078 - 12.2 - 678 - 87.9
Lithuania 22 732 1.3 572 1.5 2.5 2014 1.2 61 1.4 0.3 - 2592 - 11.4 - 511 - 89.3
Norway 55 911 3.2 692 1.8 1.2 54 473 3.4 98 2.3 0.2 - 1438 - 2.6 - 594 - 85.8
Poland 203 261 11.6 1259 3.3 0.6 183 611 11.3 300 0.7 0.2 - 1965 - 9.7 - 1229 - 97.6
Russia* 1 076 243 61.4 8445 22.2 0.8 1 022 069 63.0 1028 23.7 0.1 - 54 174 - 5.0 - 7417 - 87.8
Sweden 56 951 3.3 3786 9.9 6.6 50 163 3.1 436 10.0 0.9 - 6788 - 11.9 - 335 - 88.5
Baltic Sea** 109 299 6.2 16 869 44.3 15.4 86 106 5.3 1975 45.5 2.3 - 23 193 - 21.2 - 14 894 - 88.3
Total 1 751 844 100.0 38 068 100.0 2.2 1 623 283 100.0 4345 100.0 0.3 - 128 561 - 7.3 - 33 723 - 88.6
123
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1722 Ambio 2021, 50:1718–1730
2019). The deposition of NOx was highest in the narrow
zones on the landward side of the coastlines and decreased
moving inland. Slightly higher depositions were observed
in the central Baltic Sea as well as in the Gulf of Finland
where the ship traffic is the heaviest.
Critical load exceedances
Clearly, the tightening of sulphur regulations has led to a
decrease in the exceedance of critical loads of acidification
(Fig. 2, Table 4). After the 2015 regulation, the contribu-
tion from Baltic shipping to the exceedance of CL for
acidification is very small. The land-based sources are
dominating the effects. The highest exceedances were
found in Germany.
For the NOx effect on eutrophication, the effect of
Baltic shipping still remains considerable (Fig. 3, Table 5).
The highest exceedances were in Denmark and Germany.
In the 2030 scenarios, the exceedances will be slightly
reduced (Fig. 4, Table 5). In the future, the NECA regu-
lations will continue to reduce the exceedances, however,
only gradually as the TIER 3 only applies to newbuildings
and retrofits.
Monetary valuation of the ship-originated SOx
and NOx
The decrease in ship-originated SOx deposition from 38 kt
to 3.4 kt also decreased the monetary costs of the ecosys-
tem impacts by nearly 8 million USD, according to the
STEPWISE2006 model (Tables 6, 7). The mean values of
the three impact categories from the summary by Turner
et al. (2004) gave higher estimates for the monetary sav-
ings due to SECA. The SO2 equivalent value for impacts of
acidification from Ecovalue08 were even higher estimates,
over 130 million USD. The prevention cost model gave the
highest cost estimations, 417 million USD in 2014 and 47
million USD in 2016. Of all of these models, the Ecoval-
ue08 is the most suitable for our purposes as it takes into
account all the impacts and is more conservative than the
prevention cost method. The Baltic seascape as an entity
returned most of the benefits, due to its large size and
proximity to shipping lanes (Table 6). In terrestrial areas,
Russia, Sweden, and Finland benefitted the most (Table 1).
The monetary values of the impact categories of NOx
decreased by 2% (136 to 133 million dollars) between the
years 2014 and 2016 (Table 7). Russia benefited the most
from this small improvement.
Table 3 Atmospheric deposition of nitrogen in the study area in 2014 and 2016, respectively, calculated with average meteorology of the years
2014–2016. TOT is the total of dry and wet depositions. Depositions from Baltic Sea shipping are included in TOT, but the individual
contributions are also shown separately as SHIP. SHIP/TOT is the share of the ship-originated NOx deposition of the total deposition. *European
side of Russia. **The sea areas of the Baltic Sea
NOx deposition in 2014 NOx deposition in 2016 Change of NOx deposition from
2014 to 2016
Country TOT kt TOT
%
SHIP
kt
SHIP
%
SHIP/
TOT
TOT kt TOT
%
SHIP
kt
SHIP
%
SHIP/
TOT
TOT kt TOT
%
SHIP
kt
SHIP
%
Denmark 48 627 1.6 1822 2.3 3.7 47 391 1.6 1804 2.3 3.8 - 1236 - 2.5 - 18 - 1.0
Estonia 24 167 0.8 2193 2.8 9.1 23 605 0.8 2102 2.7 8.9 - 562 - 2.3 - 91 - 4.1
Finland 84 801 2.8 7171 9.1 8.5 82 505 2.7 6871 8.9 8.3 - 2296 - 2.7 - 3 - 4.2
Germany 588 236 19.3 2655 3.4 0.5 577 506 19.1 2586 3.3 0.4 - 1073 - 1.8 - 69 - 2.6
Latvia 41 334 1.4 2365 3.0 5.7 40 455 1.3 2311 3.0 5.7 - 879 - 2.1 - 54 - 2.3
Lithuania 54 368 1.8 1764 2.2 3.2 53 384 1.8 1770 2.3 3.3 - 984 - 1.8 6 0.3
Norway 67 491 2.2 2022 2.6 3.0 67 761 2.2 2059 2.7 3.0 27 0.4 37 1.8
Poland 376 426 12.3 4590 5.8 1.2 366 571 12.1 4560 5.9 1.2 - 9855 - 2.6 - 3 - 0.7
Russia* 1 429 360 46.8 29 156 36.9 2.0 1 428 733 47.4 28 207 36.4 2.0 - 627 0.0 - 949 - 3.3
Sweden 132 100 4.3 9387 11.9 7.1 129 422 4.3 9323 12.0 7.2 - 2678 - 2.0 - 64 - 0.7
Baltic Sea** 204 659 6.7 15 947 20.2 7.8 199 914 6.6 15 801 20.4 7.9 - 4745 - 2.3 - 146 - 0.9
Total 3051 569 100.0 79 072 100.0 2.6 3 017 247 100.0 77 394 100.0 2.6 - 34 322 - 1.1 - 1678 - 2.1
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DISCUSSION
The reduction in sulphur deposition
Sulphur emissions originate from several sources mainly
from industry and traffic, of which shipping is one part.
Industry and land-based traffic have successfully decreased
their emission. This has greatly reduced the size of the area
in Europe where sulphur deposition exceeds critical loads,
but shipping has been lagging behind (Amann et al. 2011).
The implementation of the IMO MARRPOL Annex VI
regulations has led to a steep decrease in SOx emissions
from shipping (Johansson et al. 2013; Jonson et al. 2015;
IMO 2017; HELCOM 2018 pp. 41, 42).
Table 4 Exceeded area (Exarea; in percent of the total ecosystem area given in column 2) and exceedance (AAE; in eq/ha/a) for critical loads of
acidification for the five deposition scenarios in the countries bordering the Baltic Sea (including Norway). DE:Germany, DK:Denmark,
EE:Estonia, FI:Finland, LT:Lithuania, LV:Latvia, NO:Norway, PL:Poland, RU:Russia, SE:Sweden
Scenario Base NoBl Bl2014 Base-BAU2030 NoBl-BAU2030
Ecoarea
(km2)
Exarea
(%)
AAE
(eq/ha/a)
Exarea
(%)
AAE
(eq/ha/a)
Exarea
(%)
AAE
(eq/ha/a)
Exarea
(%)
AAE
(eq/ha/a)
Exarea
(%)
AAE
(eq/ha/a)
DE 106 870.5 44.1 246.5 43.9 244.1 44.2 247.4 24.4 100.2 24.3 99.1
DK 5692.3 11.9 14.3 6.7 9.1 13.7 18.0 1.4 3.0 1.2 2.6
EE 27 229.7 0.1 0.1 0.1 0.1 0.1 0.1 0 0 0 0
FI 286.0 0.7 0.4 0.6 0.3 0.7 0.4 0.6 0.3 0.6 0.3
LT 22 197.8 28.4 83.2 27.9 78.1 28.6 84.6 25.2 44.6 24.8 42.2
LV 36 630.2 3.7 3.4 2.8 2.8 3.8 3.6 1.8 1.4 1.7 1.2
NO 320 449.3 11.3 20.2 10.9 19.0 11.4 20.6 8.5 11.4 8.3 11.0
PL 96 845.7 32.9 120.2 32.3 117.6 33.1 121.0 15.0 34.3 14.8 33.6
RU 624 631.4 1.6 1.7 1.4 1.7 1.7 1.8 1.0 1.5 1.0 1.5
SE 395 225.1 5.2 3.6 5.1 3.2 5.7 4.1 3.8 1.9 3.8 1.8
All 1 636 058.0 9.4 30.0 9.1 29.2 9.6 30.3 5.9 12.5 5.8 12.2
eq ha-1yr-1
not exceeded
< 50
50 - 100
100 - 200
200 - 500
> 500
Exceedance of CLaci Deposition: Base
Dep-data: EMEP/MSC-W
IIASA
eq ha-1yr-1
not exceeded
< 50
50 - 100
100 - 200
200 - 500
> 500
Exceedance of CLaci Deposition: Base-BAU2030
Dep-data: EMEP/MSC-W
IIASA
Fig. 2 Exceedance of critical loads of acidification (CLaci) under the 2016 and 2030 base scenarios. Exceedances are displayed as average
accumulated exceedance (AAE) in every 0.50 9 0.25 grid cell
123
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1724 Ambio 2021, 50:1718–1730
The direct environmental impacts of SOx are related to
acidification. Acidification has different impacts on the
natural environment in soils (van Breemen et al. 1982),
freshwaters (Krzyzanowski and Innes 2010), oceans, and
brackish waters. In particular, calcifying species in the sea
are under threat (Azevedo et al. 2015). However, ocean
acidification is mostly linked to rising CO2 levels, and
oceans are generally well buffered against sulphur acidifi-
cation (LeDuc et al. 2014; Stips et al. 2016). The SOx
emissions from shipping, however, form strong acids and,
thus, may cause pH reductions of the same order of mag-
nitude as the weak carbonic acid formed from CO2
eq ha-1yr-1
not exceeded
< 50
50 - 100
100 - 200
200 - 500
> 500
Exceedance of CLeutN Deposition: Base
Dep-data: EMEP/MSC-W
IIASA
eq ha-1yr-1
not exceeded
< 50
50 - 100
100 - 200
200 - 500
> 500
Exceedance of CLeutN Deposition: Base-BAU2030
Dep-data: EMEP/MSC-W
IIASA
Fig. 3 Exceedance of critical loads of eutrophication (CLeutN) under the 2016 and 2030 base scenarios. Exceedances are displayed as average
accumulated exceedance (AAE) in every 0.50 9 0.25 grid cell. Note: Exceedances of eutrophication CLs are computed by using total N
deposition, whereas for exceedances of acidity CLs, both total S and N deposition are needed, in both cases considering also land cover
Table 5 Exceeded area (Exarea; in percent of the total ecosystem area given in column 2) and exceedance (AAE; in eq/ha/a) for critical loads of
eutrophication for the five deposition scenarios in the countries bordering the Baltic Sea (including Norway). DE: Germany, DK:Denmark,
EE:Estonia, FI:Finland, LT:Lithuania, LV:Latvia, NO:Norway, PL:Poland, RU:Russia, SE:Sweden
Scenario Base NoBl Bl2014 Base-BAU2030 NoBl-BAU2030
Ecoarea
(km2)
Exarea
(%)
AAE
(eq/ha/a)
Exarea
(%)
AAE
(eq/ha/a)
Exarea
(%)
AAE
(eq/ha/a)
Exarea
(%)
AAE
(eq/ha/a)
Exarea
(%)
AAE
(eq/ha/a)
DE 106 870.5 77.4 623.8 77.3 618.4 77.4 623.9 67.2 365.6 67.2 362.7
DK 5692.3 100.0 653.5 100.0 607.7 100.0 655 100.0 468.8 100.0 446.7
EE 27 229.7 74.8 58.9 59.0 33.2 75.1 60.3 41.9 23.4 29.8 18.0
FI 41 068.5 6.0 2.9 3.2 1.1 6.1 3.0 1.4 0.6 0.8 0.3
LT 22 197.8 99.2 388.5 98.9 366.9 99.2 388.4 97.8 284.1 97.6 273.1
LV 36 630.2 93.9 173.7 91.6 148.5 93.9 174.3 87.8 124.6 83.4 113.7
NO 302 948.7 11.2 18.8 10.5 16.7 11.1 18.7 6.4 7.1 6.0 6.5
PL 96 845.7 70.1 289.0 69.0 280.4 70.1 289.1 55.7 150.4 55.0 147.1
RU 624 631.4 46.2 67.7 44.6 63.2 46.2 67.9 41.3 50.7 40.1 48.5
SE 56 674.5 11.0 23.5 10.1 19.7 10.9 23.5 9.6 13.3 9.2 11.7
All 1 320 789.0 42.7 124.5 41.2 118.8 42.7 124.6 36.3 77.6 35.2 75.1
 The Author(s) 2021
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Ambio 2021, 50:1718–1730 1725
acidification in ocean waters, especially in heavily traf-
ficked areas (Hassello¨v et al. 2013; Stips et al. 2016). Still,
in the Baltic Sea, the long-term effects of ship-borne acid
deposition, including scrubber wash water, on pH and
alkalinity should be small, especially in the surface waters
(Turner et al. 2018). This is because the Baltic Sea surface
waters are exported to the North Sea (Turner et al. 2018).
The Baltic Sea is predicted to be warmer, less saline, and
more acid in the future due to climate change and cumu-
lative impacts of other stressors (Jutterstro¨m et al. 2014), of
mol ha-1yr-1
no exceedance
< 10
10 - 30
30 - 50
50 - 70
> 70
CLeutN exceedance Base minus NoBl
Dep-data: EMEP/MSC-W
IIASA
mol ha-1yr-1
no exceedance
< 10
10 - 30
30 - 50
50 - 70
> 70
CLeutN exceedance Bl2014 minus Base
Dep-data: EMEP/MSC-W
IIASA
mol ha-1yr-1
no exceedance
< 10
10 - 30
30 - 50
50 - 70
> 70
CLeutN exceedance Base-BAU2030 minus NoBl-BAU2030
Dep-data: EMEP/MSC-W
IIASA
mol ha-1yr-1
no exceedance
< 10
10 - 30
30 - 50
50 - 70
> 70
CLeutN exceedance Base minus Base-BAU2030
Dep-data: EMEP/MSC-W
IIASA
Fig. 4 Maps of differences in CLeutN exceedances (AAE) between four combinations of the scenarios (scenario names on the upper right of
each map). Note: ‘no exceedance’ means that the CLs in that grid cell are not exceeded by either deposition
123
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1726 Ambio 2021, 50:1718–1730
which shipping is one. A decrease in and lower levels of
ship-originated SOx in order to avoid negative ecosystem
developments have been achieved by regulations, but the
scrubber wash waters also need to be regulated. The non-
linear dynamics in marine ecosystems call for precautions
in management (Scharin et al. 2016). In addition to the
impacts on ecosystems, SOx damages buildings and cul-
tural heritage that are part of the monetisation models.
If the critical loads of acidification are exceeded, it may
decrease biodiversity, which holds value for humans in
many ways. From a management point of view, a safe
strategy seems to be to require a minimum level of biodi-
versity for any ecosystem to be sustained (Arrow et al.
1996). The central question in valuing biodiversity has
been whether we should value all elements of biodiversity
(e.g. the existence of species, the resilience of communi-
ties, etc.) in monetary terms or whether they should possess
an intrinsic value regardless of human benefit (Nunes and
van den Bergh 2001).
Monetisation of the deposition of ship-originated
SOx
The monetisation analysis of SOx and NOx in the Baltic
Sea Region covers terrestrial and sea areas including land,
lake and brackish water areas. Considering the large geo-
graphical area, and differences in the effects on different
waterbodies and land sites, it is clear that using a single
coefficient to cover it all is not very accurate. On the other
hand, conducting a finer scale analysis on this large area is
practically impossible. In this study, we have carried out
the best possible large-scale analysis with current
Table 6 Monetary valuation of the change in environmental impacts regarding SOx deposition from Baltic Sea shipping in 2014 and 2016 and
the change from 2014 to 2016. Three sets of values for environmental impacts were applied: A, B, and C (see Table 1 for the composition of the
monetary values). The results are presented in thousand USD2018. A is the ecosystem impacts alone from STEPWISE2006. B consists of the sum
of values from the impact categories of agriculture, buildings, and ecosystems from Turner et al. (2004). C is the SO2 equivalent values of
acidification of Ecovalue08 from Ahlroth & Finnveden (2011). D is the SOx equivalent values of prevention of acidification from Vogtla¨nder and
Bijma (2000). *European side of Russia (See Fig. 1). **The sea areas of the Baltic Sea
Country A
2014,
k$
A
2016,
k$
A change
2014 to
2016, k$
B
2014,
k$
B
2016,
k$
B change
2014 to
2016, k$
C 2014,
k$
C
2016,
k$
C change
2014 to
2016, k$
D 2014,
k$
D
2016,
k$
D change
2014 to
2016, k$
Denmark 231 23 - 208 1342 135 - 1206 3795 383 - 3413 10 771 1086 - 9685
Estonia 183 20 - 163 1060 115 - 945 2999 325 - 2675 8511 921 - 7590
Finland 628 69 - 559 3642 400 - 3242 10 304 1132 - 9171 29 241 3214 - 26 027
Germany 294 35 - 259 1708 202 - 1506 4831 572 - 4259 13 710 1623 - 12 087
Latvia 182 22 - 160 1053 127 - 926 2980 359 - 2620 8456 1020 - 7436
Lithuania 135 14 - 120 781 83 - 698 2211 236 - 1975 6274 669 - 5605
Norway 163 23 - 140 945 134 - 812 2675 379 - 2296 7590 1075 - 6515
Poland 297 7 - 289 1720 41 - 1679 4866 116 - 4750 13 809 329 - 13 480
Russia* 1989 242 - 1747 11 538 1404 - 10 133 32 639 3973 - 28 666 92 625 11 275 - 81 350
Sweden 892 103 - 789 5172 596 - 4577 14 633 1685 - 12 947 41 525 4782 - 36 743
Baltic Sea** 3973 465 - 3508 23 046 2698 - 20348 65 197 7633 - 57 564 185 019 21 662 - 163 358
Total 8967 1023 - 7943 52 008 5936 - 46072 147 129 16 793 - 130 336 417 530 47 656 - 369 874
Table 7 Monetary valuation of the change in environmental impacts
regarding NOx deposition from Baltic Sea shipping in 2014 and 2016
and the change from 2014 to 2016. See Table 1 for the composition of
the monetary values. E consists of the sum of values from the impact
categories of agriculture, buildings, ecosystems and fertilisation
effects from Turner et al. (2004) and Weidema (2009). Results are
presented in USD2018. *European side of Russia. **The sea areas of
the Baltic Sea
Country D 2014, k$ D 2016, k$ D change from
2014 to 2016, k$
Denmark 3147 3116 - 31
Estonia 3788 3631 - 157
Finland 12 387 11 869 - 518
Germany 4586 4467 - 119
Latvia 4085 3992 - 93
Lithuania 3047 3057 ?10
Norway 3493 3557 ?64
Poland 7929 7877 - 52
Russia* 50 363 48 724 - 1639
Sweden 16 215 16 104 - 111
Baltic Sea** 27 546 27 294 - 252
Total 136 586 133 688 - 2899
 The Author(s) 2021
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Ambio 2021, 50:1718–1730 1727
monetisation values. The environmental effects of
strengthening the SECA have not been analysed before.
The analysis was necessary in order to compare the costs of
regulation to the benefits by using the same kind of
methodology as was being used in an ex-ante analysis. For
this discussion, we bring in the environmental benefit of
130 million USD. This can be compared to the costs of
compliance of 662 million dollars (Repka et al. 2019), and
the health benefits based on decreased mortality of at least
557 million dollars (Barrega˚rd et al. 2019). Thus, the health
and environmental benefits of the regulations exceed the
control costs.
Nitrogen deposition
A significant amount of nitrogen still originates from the
shipping in the Baltic Sea. High levels of NOx depositions
also extend into northern Germany and Denmark. The max-
imum deposition from the Baltic Sea shipping is along the
coastlines rather than in the shipping lanes where ammonium
nitrate is formed in combination with ammonia that mainly
comes from agriculture (Jonson et al. 2019). In many coastal
areas of the Baltic Sea, more than 10% of the total amount of
nitrogen deposition is due to shipping. Typically, dry depo-
sitions on subgrid-scale forest ecosystems (both coniferous
and deciduous) are higher than the grid average.
The deposition of nitrogen has been estimated to have a
larger impact on the terrestrial environment than SOx, which
after 2015 was mostly concentrated in the sea areas. Com-
pared with the STEPWISE2006 model, values for eutrophi-
cation from the other models for the valuation of N are almost
three times higher; however, it should be noted that they all
have different methods and scopes (Pizzol et al. 2015).
Excess nitrogen causes eutrophication in freshwater and
affects species decomposition on terrestrial ecosystems
leading to loss of biodiversity (e.g. Rabalais 2002; Stevens
et al. 2010); this is supported by the results of the critical
load analysis which shows that the CLs are exceeded in the
southern part of the BSR and this will continue in the
future. Thus, more stringent regulation is needed, and in
2021, the NECA will be tightened (IMO 2017). Since the
volume of maritime traffic has remained approximately the
same and NOx emissions have even increased in some
areas, this shows that the current level of NOx regulation is
not sufficient, mainly because it only concerns new ships
(Fig. 4). However, it will be more successful in coming
years when the fleet is renewed with TIER III vessels.
CONCLUSIONS
In policy assessments, all categories of environmental and
health aspects should be included and not just human
health (La¨hteenma¨ki-Uutela et al. 2017). This is the first
attempt to monetarise the environmental benefits of SECA
regulation, and we noticed that there is a lot of uncertainty
in the monetarization methods. There are no good esti-
mates for the acidification of the Baltic Sea, and we were
forced to use the same coefficients as for land areas.
Another message is the need to develop valuation of dif-
ferent types of ecosystems, as it is needed in political
discussion of environmental protection.
Acknowledgements This research was funded by the EnviSuM
project (no R1.074) of the Baltic Sea Region Interreg programme and
by the Strategic Research Council at the Academy of Finland, project
SmartSea (grant number 292 985). We thank Asko Ija¨s and Minna
Alhosalo for help with calculations. We are grateful for the Baltic Sea
countries and HELCOM for allowing the use of their Automatic
Identification System data in this study.
Funding Open Access funding provided by University of Turku
(UTU) including Turku University Central Hospital.
Open Access This article is licensed under a Creative Commons
Attribution 4.0 International License, which permits use, sharing,
adaptation, distribution and reproduction in any medium or format, as
long as you give appropriate credit to the original author(s) and the
source, provide a link to the Creative Commons licence, and indicate
if changes were made. The images or other third party material in this
article are included in the article’s Creative Commons licence, unless
indicated otherwise in a credit line to the material. If material is not
included in the article’s Creative Commons licence and your intended
use is not permitted by statutory regulation or exceeds the permitted
use, you will need to obtain permission directly from the copyright
holder. To view a copy of this licence, visit http://creativecommons.
org/licenses/by/4.0/.
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AUTHOR BIOGRAPHIES
Sari Repka (&) is a Project Manager at the University of Turku,
Centre for Maritime Studies at Brahea Center. Her research interests
include aquatic ecology, environmental effects of shipping and blue
growth. Corresponding author.
Address: Brahe Centre, Centre for Maritime Studies, University of
Turku, University of Turku, 20014, P.O. Box 181, 28101 Pori, Fin-
land.
e-mail: sari.repka@utu.fi
Anne Erkkila¨-Va¨lima¨ki is a Senior Advicer at the University of
Turku, Centre for Maritime Studies at Brahea Center. Her research
interests include remote sensing, blue growth and geoinformatics.
Address: Brahe Centre, Centre for Maritime Studies, University of
Turku, University of Turku, 20014, P.O. Box 181, 28101 Pori, Fin-
land.
e-mail: anne.erkkila-valimaki@utu.fi
Jan Eiof Jonson is a Scientist at Norwegian Meteorological Institute.
His research interests include air quality, meteorology and atmo-
spheric modelling.
Address: Norwegian Meteorological Institute, Henrik Mohns plass 1,
0313 Oslo, Norway.
e-mail: janeij@met.no
Maximilian Posch is a Guest Research Scholar at the International
Institute for Applied Systems Analysis. His research interests include
air quality, critical loads and dynamic modelling.
Address: International Institute for Applied Systems Analysis
(IIASA), 2361 Laxenburg, Austria.
e-mail: posch@iiasa.ac.at
Janne To¨rro¨nen is a Project Researcher at the University of Turku,
Centre for Maritime Studies at Brahea Center. His research interests
include hydrology, geoinformatics and blue growth.
Address: Brahe Centre, Centre for Maritime Studies, University of
Turku, University of Turku, 20014, P.O. Box 181, 28101 Pori, Fin-
land.
e-mail: janne.torronen@utu.fi
Jukka Pekka Jalkanen is a Senior Researcher at the Finnish Mete-
orological Institute. His research interests include ship emission
modelling, air quality and greenhouse gas emissions.
Address: Finnish Meteorological Institute, P.O. Box 503, 00101
Helsinki, Finland.
e-mail: jukka-pekka.jalkanen@utu.fi
123
 The Author(s) 2021
www.kva.se/en
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