Pollution of the Marine Environment from or Through the Atmosphere (James Harrison)


James Harrison

6.1 Introduction

Parties to the 1982 United Nations Convention on the Law of the Sea (UNCLOS) are under an obligation to take measures to prevent, reduce and control ‘all sources of pollution of the marine environment’.1 The term ‘marine environment’ is not explicitly defined by the Convention and the scope of this provision is ambiguous. On one reading of the term, it includes the air space above the water column and therefore pollution of the air is itself pollution of the marine environment.2 Yet, even if one accepts that the Convention ‘does not address directly the problem of pollution of the atmosphere itself’,3 it is clear that polluting substances can enter the water column from the atmosphere, either through precipitation or through the direct deposit of particulates.4 Indeed, the Convention explicitly covers ‘pollution of the marine environment from or through the atmosphere’,5 thereby recognizing the complex interactions between the air and the sea.

This chapter considers the international law that is applicable to pollution of the marine environment from or through the atmosphere. It will start by explaining the way in which this issue is addressed in UNCLOS. It will then analyse other relevant instruments that have been adopted to combat air pollution. The chapter will cover both general treaties on air pollution, as well as the specific regime for the prevention of air pollution from ships. It will pay particular attention to the nature of the international regulations and the extent to which they balance the various interests of different States. It will also consider the manner in which the international emissions standards have evolved in response to technological developments and the challenges for future evolution.

6.2 Scope and Nature of the Problem

Air-borne pollutants are a significant threat to human health, causing premature mortality, cardiopulmonary disease, lung cancer, and chronic respiratory ailments. However, they can also cause damage to the environment more generally. One study notes that ‘acid depositation [through precipitation] has been blamed for increased acidity of soil, lakes, and rivers and for other effects including reduced crop growth, death or degradation of forests, and the disappearance of fish and wildlife’.6 Nor are these effects limited to the terrestrial environment.

Whilst precise figures remain uncertain, it is estimated that the atmosphere is the source of many contaminants in the marine environment, including nitrogen, sulphur, carbon, heavy metals, and other organic compounds.7 These substances contribute to pollution of the marine environment when they are absorbed into the water column. Sulphur, nitrogen, and carbon deposits can all lower pH levels of seawater causing ocean acidification, which is thought to ‘have a considerable impact on calcifying organisms and the food-webs of which they are part’.8 Furthermore, CO2 emissions also contribute to climate change, which has additional negative effects on the oceans, such as sea-level rise and water warming.9

There are various sources of pollution from or through the atmosphere. Clearly, land-based activities, such as factories or other industrial facilities, are a major source of such pollution as fumes can be blown over the seas by winds, depositing pollutants into the water column. The seriousness of this problem will depend on a number of factors including meteorological conditions and the atmospheric residence time of a contaminant.10 As noted by one scientific study:

Since source of contaminants are mainly in mid-latitudes in the northern hemisphere, materials tend on balance to move from west to east, although in the case of specific events (e.g. the Chernobyl accident) weather conditions at the time of release determine the paths of the emissions. In general, North America contributes to the North Atlantic Ocean, and the Asian continent influences the North Pacific and Arctic Oceans. On the other hand, movement in the trade wind zone is from east to west so that the flow from southern North America is across the north Pacific and from north Africa across the north Atlantic.11

Alongside land-based sources, ships are also a source of air pollution. Indeed, shipping is becoming a more serious source of air pollution as emissions from land-based sources become subject to increasingly strict regulation at the national and international level.12 Emissions from shipping include sulphur dioxide, nitrogen oxide, and other particulate matter. Furthermore, the International Maritime Organization (IMO) has estimated that ships engaged in international trade contribute about 2.1 per cent of global greenhouse gas emissions on a CO2 equivalent basis.13

By its very nature, air pollution is easily transferred across international boundaries. Therefore it is a topic that has long been subject to international rules and regulations. Over time, the body of law in this area has shifted from ascribing responsibility for transboundary air pollution14 to trying to limit the production of air pollutants at source.15 International cooperation is also important in the case of air pollution from ships, given that they travel around the world and they are subject to numerous jurisdictions.16 The following sections will explain and evaluate the legal framework for the regulation of air pollution, with a particular focus on ships given their close link with pollution of the marine environment.

6.3 Pollution from or through the Atmosphere under UNCLOS

Pollution of the marine environment from or through the atmosphere is expressly regulated by Article 212 of UNCLOS. First and foremost, Article 212(1) requires states to ‘adopt laws and regulations to prevent, reduce and control pollution of the marine environment from or through the atmosphere, applicable to the air space under their sovereignty and to vessels flying their flag or vessels or aircraft of their registry’.17 It is apparent that Article 212(1) has a broad scope and it covers both air pollution produced by all activities within the sovereign territory of a state, as well as air pollution from ships and aircrafts of their nationality, wherever they are in the world. All parties to the Convention are expected to control these sources through legislation, as well as to take ‘other measures as may be necessary to prevent, reduce and control such pollution’.18

Recognizing the need for international cooperation, Article 212(3) encourages states to ‘establish global and regional rules, standards and recommended practices and procedures’ to prevent, reduce and control pollution of the marine environment from or through the atmosphere, applicable to inter alia air space under their sovereignty and vessels flying their flag.19 Given the breadth of Article 212, it is not surprising that paragraph 3 makes reference to international organizations in the plural.20 There is no single organization which has responsibility for air pollution issues at the international level. The UN Division for Ocean Affairs and the Law of the Sea has identified a range of instruments as relevant for the purposes of Article 212, including the Vienna Convention for the Protection of the Ozone Layer21 and its Montreal Protocol22, the United Nations Framework Convention on Climate Change23 and its Kyoto Protocol24, and relevant regional agreements.25

Indeed, potential overlaps may arise. This is particularly the case when it comes to the regulation of air pollution from ships. Many of the general air pollution treaties discussed below potentially apply to ships, particularly when they are within the jurisdiction of a State. At the same time, the IMO itself claims that it is ‘the appropriate forum for States to establish global and regional rules, standards and recommended practices and procedures applicable to vessels to prevent, reduce and control pollution of the marine environment from or through the atmosphere’.26 The need for specific regulations to address the prevention of air pollution from ships was first recognized in Resolution A.719(17) adopted by the IMO Assembly in November 1991, in which the Organization agreed to negotiate a new annex to the International Convention for the Prevention of Pollution from Ships (MARPOL)27 to address this issue.28 MARPOL Annex VI was ultimately adopted in 1997. Although the IMO has taken into account many of the existing international instruments addressing air pollution in negotiating its own response to air pollution,29 questions about the interrelationship between the IMO and other relevant bodies may arise. The following sections will therefore consider both the general air pollution treaties, as well as the relevant provisions of MARPOL Annex VI.

The scope of Article 212 covers any potential pollutant of the marine environment from or through the atmosphere. However, due to space constraints, this chapter will focus on three of the most important atmospheric pollutants, namely sulphur oxides, nitrogen oxides, and carbon dioxide.

6.4 Regulation and Control of Sulphur Oxides and Particulate Matter

Sulphur Oxides (SOx) are caused by a number of anthropocentric activities, particularly the burning of fossil fuels. Emissions of SOx were first regulated at the regional level in North America and Europe by a Protocol adopted in 1985 under the 1979 Convention on Long-Range Transboundary Air Pollution30 which committed the parties to ‘reduce their national annual sulphur emissions or their transboundary fluxes by at least 30%’.31 The precise scope of the Protocol was not specified, but it potentially included emissions from shipping.32 Nine years later, parties to the 1979 Convention adopted an additional Protocol on Further Reduction of Sulphur Emissions.33 This instrument set individual targets for states to meet. Although some of the provisions of the Protocol could potentially apply to shipping when within the jurisdiction of a party34, States chose to adopt a global response to counter sulphur emission from ships at the IMO, in order to avoid unequal adverse effects on the economic operators in affected regions.35

Regulation 14 of MARPOL Annex VI addresses SOx emissions from international shipping by setting standards for the sulphur content of fuel oils used on board ships. In the original text, a single standard was set for the sulphur content of fuel.36 However, amendments agreed in 2008 introduced incremental standards as follows:37

– 4.5 per cent m/m prior to 1 January 2012

– 3.5 per cent m/m on and after 1 January 2012

– 0.5 per cent m/m on and after 1 January 2020

This provision directly addresses the reduction of SOx emissions by reducing the sulphur content of marine fuel. However, parties are also permitted to allow other abatement techniques to be used in place of the standards prescribed by the Annex, provided they are ‘at least as effective in terms of emissions reductions’.38

The Regulation also includes the possibility of applying higher standards for specific areas which are designated as SOx Emission Control Areas (ECAs). The premise behind the ECAs is that certain geographical areas are more vulnerable to ambient concentrations of air pollution and therefore stricter standards should be applied.39 Thus, in designated areas, all ships must comply with stricter fuel content requirements:40

– 1.5 per cent m/m prior to 1 July 2010

– 1.0 per cent m/m on and after 1 July 2010

– 0.1 per cent m/m on and after 1 January 2015

The inclusion of ECAs was also, however, intended to achieve a compromise between those states that wanted high levels of reductions and those actors that were resistant to regulation.41 Thus, it is an example of how the IMO has balanced the various interests of different states in order to achieve global regulation of shipping emissions.

In the original text, the Baltic Sea was specifically designated as a SOx ECA and a power was conferred on the Marine Environmental Protection Committee (MEPC) of the IMO to designate additional ECAs. In making a designation, the MEPC shall take into account, inter alia, the human populations and environmental areas at risk, the nature of ship traffic in the area, the meteorological conditions in the area, as well as existing control measures taken by the proposing state to address land-based sources of pollutants.42 Three additional SOx ECAs have since been designated: the North Sea SOx ECA;43 the North American SOx ECA;44 and the United States Caribbean Sea SOx ECA.45

There has been some resistance to the designation of ECAs, largely because of the increased costs that they will impose on ships operating in the designated areas. In 2012, the State of Alaska sought to challenge in the United States courts the validity of the amendment to MARPOL Annex VI designating the North American SOx ECA. According to the claimants, the effect of the ECA’s low sulphur requirements would be to increase shipping costs by 8 per cent, thereby increasing the costs of goods shipped into the state. The claimants argued, inter alia, that the designation of the ECA was invalid because it did not comply with the requirements of Appendix III of Annex VI as the effects of air pollution in Alaska had not been properly quantified.46 The claims were eventually dismissed by the District Court for the District of Alaska due to lack of jurisdiction.47 In any case, the claimants would seem to have overstated the role of the criteria contained in Annex III and the MEPC would seem to have a broad degree of discretion in designating ECAs as it must only ‘take into account’ the Annex III criteria.48

The principal means of enforcing Regulation 14 is through port State control of relevant documentation. To this end, suppliers are required under the Regulation to document the sulphur content of fuel provided by them49 and ‘details of fuel oil for combustion purposes delivered to and used on board shall be recorded by means of a bunker delivery note (BDN)’.50 The BDN must also be accompanied by a fuel sample which must be retained onboard the ship.51 Port States are explicitly empowered to inspect the BDN.52 Yet, it has been pointed out that there are problems with relying on these documents, as they were not originally designed to perform a regulatory function.53 In particular, the BDN is not always written in English and it often takes the form of a carbon copy which may not be legible. A controversy has also arisen over whether port States are able to test the fuel samples accompanying the BDN. Whilst some states do carry out this practice, it has been pointed out by some delegates in the MEPC that ‘under regulation 14 of MARPOL Annex VI, sampling of fuel oil used on board ships is not identified as a means to determine compliance and that there was potential for the ship to be unduly delayed for fuel oil sampling and analysis’.54 There was no consensus on how to proceed with this issue and the MEPC has called for further consideration of the matter.55 Yet, this is a matter that the shipping industry has flagged as being of major importance, expressing a particular concern about the potential for inconsistent implementation, leading to unfair competition between operators.56 Another problem arises when fuel is purchased in countries which are not a party to MARPOL Annex VI. Although this issue was raised at the MEPC, the Committee took no action apart from confirming that it is the ship that is responsible for documenting compliance with Regulations 14 and 18 and also ‘inviting’ non-parties to institute measures to ensure that ships are provided with the necessary BDN and representative samples of fuel oil delivered.57 This issue highlights the difficulty of implementing shipping regulations at the international level in a comprehensive and consistent manner.

In recognition of the fact that compliance relies upon the availability of compliant fuel, a shipowner is permitted to defend a claim of non-compliance by showing that they made best efforts to purchase fuel in compliance with the regulations but it was not available.58 Although there is no objective definition of ‘best efforts’, the regulation does clarify that ‘[a] ship should not be required to deviate from its intended voyage or to delay unduly the voyage in order to achieve compliance’.59 This provision puts the impetus on port States to ensure that sufficient supplies of fuel are available at all of their international ports.60 In order to avoid bad faith claims by shipowners, they are required to inform their flag State and the port State when they cannot purchase compliant fuel oil at a particular port.61 The Annex also requires a review of fuel oil availability to be carried out by the MEPC62 in order to determine whether the stricter standards due to be applied in January 2020 should be implemented at that time or delayed until January 2025.63 This emphasizes the close interrelationship between economic and technological developments and the successful reduction of emissions.

6.5 Regulation and Control of Nitrogen Oxides

Nitrogen Oxides (NOx) are formed, inter alia, through the combination of Nitrogen and Oxygen during the combustion process. This gas is produced both through land-based industrial activity and through ship engines. Like SOx, NOx pollution was also initially addressed at a regional level in North America and Western Europe under the auspices of the 1979 Convention on Long-Range Transboundary Air Pollution. A 1988 Protocol required states to ‘take effective measures to control and/or reduce their national annual emissions of nitrogen oxides or their transboundary fluxes’ and it introduced targets for the contracting parties to meet.64 How states were to meet these targets was left to their discretion.

The 1988 Protocol applies to both stationary and mobile sources of NOx emissions and it therefore potentially applies to ships.65 However, as noted by the Technical Annex to the Protocol, ‘until other data become available this annex concentrates on road vehicles only’66 and therefore parties are not obliged to take measures relating to shipping into order to meet their commitments under the Protocol. Moreover, it was generally recognized that NOx emissions from shipping were best addressed at the global level, as opposed to through a regional treaty. The issue was therefore addressed by the IMO in the negotiation of MARPOL Annex VI.

Regulation 13 of MARPOL Annex VI addresses the emission of NOx by marine diesel engines. Generally speaking, this is achieved through the establishment of technical standards to be applied to the design and construction of ship engines. As a result, the regulations are largely prospective, only applying to newly constructed ships, although a major exception to this principle will be noted below.

The original text of Regulation 13 established limits for the emission of NOx for marine diesel engines installed on a ship constructed on or after 1 January 2000. The standards also apply where a marine diesel engine undergoes a major conversion after that date.67 Amendments to Annex VI agreed in 2008 further decreased limits for NOx emissions that apply to ships built on or after 1 January 2011.68 The 2008 amendments also created an exception to the general rule of non-retroactivity in the emissions standards. This additional regulation sought to alleviate the concerns of some states that the long life of many ships could mean that improvements in air quality would not be achieved, despite the introduction of standards for new ships. The change was possible because it had been discovered since the adoption of the original Annex VI that reductions in emissions may be achieved in existing engines through relatively minor adjustments.69 Thus, a new provision was inserted into Regulation 13 that requires ships built on or after 1 January 1990 but prior to 1 January 2000 to comply with the emissions standards for certain types of engines,70 if an ‘Approved Method’ has been certified by the flag State.71 Ship owners have 12 months from the notification of the Approved Method to make changes to their engines. However, the standards that apply in this case are lower than the standards that apply to new ships.72 Table 6.1 above summarizes the NOx emissions standards for ships.

Table 6.1NOx Emissions Standards under MARPOL Annex VI, Regulation 13


Regulation 13 also allows for the possibility for NOx ECAs.73 Ships built on or after 1 January 2016 will therefore also have to comply with stricter standards when operating in a NOx ECA designated by the IMO.74 There are currently two NOx ECAs that have been designated: the North American NOx ECA75 and the Caribbean United States NOx ECA.76

To assist engine manufacturers and shipowners to comply with Regulation 13, the IMO has produced a Technical Code on Control of Emission of Nitrogen Oxides from Marine Diesel Engines.77 The NOx Technical Code is mandatory for all marine diesel engines with a power output of more than 130 KW installed on ships subject to Regulation 13.78 According to the Code, engines must be pre-certified as complying with its requirements. Engines must then be tested again once they have been installed onboard a vessel to ensure that any adjustments that have been made in the installation process have not affected the ability of the engine to meet the emissions standards. Ships meeting the requirements of Annex VI must carry an International Air Pollution Certificate issued by the flag State after a survey of the ship’s equipment, systems and fittings.79 Certificates last up to five years, at which time the ship must undergo a renewal survey and receive a new certificate.80 The certificate must also be presented to port State control officers who may verify that it is valid and, if the evidence so warrants, carry out more detailed inspections.81

Recognizing that the NOx limits will only be met by the development of appropriate technology, the Regulation provides that ‘beginning in 2012 and completed no later than 2013, the Organization shall review the status of the technological developments to implement the standards set forth in paragraph 5.1.1 of this regulation and shall, if proven necessary, adjust time periods set forth in that paragraph’.82 Any adjustments may be made using the tacit amendment procedures found in the MARPOL Convention.83 In other words, once adopted, amendments will automatically become binding on parties, unless they make an express declaration to the contrary.84 This procedure facilitates the rapid development of the Convention to meet contemporary challenges. Whilst this mechanism could be used to delay the introduction of higher standards if the technology was not in place, it could also potentially be used to strengthen them. Indeed, Resolution 3 adopted at the 1997 Air Pollution Conference explicitly calls upon MEPC to review the NOx limits at five-year intervals ‘with the aim of prescribing more stringent emission limits, taking into account the adverse effects of such emissions on the environment and any technological developments in marine engines’.85 This anticipates a progressive strengthening of the regulations, although its actualization depends upon mobilizing sufficient political will of IMO Member States.

6.6 Regulation and Control of Greenhouse Gas (GHG) Emissions

The contribution to climate change by anthropocentric emissions of greenhouse gases, such as carbon dioxide, is today well-documented. The IPPC has stated that ‘most of the observed increase in global average temperature since the mid-20th century is very likely due to the observed increase in anthropocentric GHG concentrations’.86 The effects of such a temperature increase would be profound for the whole planet, including for the oceans. As one study says, ‘present and predicted effects include increases in sea-surface temperature; increases in sea level; and, decreases in sea-ice cover. Changes in salinity and ocean circulation may also occur’.87 All kinds of human activities contribute to GHG emissions.

The international community has responded to this threat by the adoption of the UN Framework Convention on Climate Change (UNFCCC) that seeks to achieve ‘stabilization of [GHG] concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system’.88 An important feature of the UNFCCC is that it is based upon the principle of common but differentiated responsibilities, meaning that ‘developed country Parties should take the lead in combatting climate change and the adverse effects thereof’.89 Thus, whilst all parties to the UNFCCC are required to develop national inventories of GHG emissions and take measures to mitigate climate change from anthropocentric sources, only the developed country parties have binding commitments to meet specific GHG targets, as set out in the Kyoto Protocol.

Unlike the general air pollution treaties discussed above, the Kyoto Protocol explicitly addresses shipping emissions. It provides that ‘the Parties included in Annex I (ie developed countries) shall pursue limitation or reduction of emissions of greenhouse gas emissions not controlled by the Montreal Protocol from…marine bunker fuels, working through…the International Maritime Organization’.90

In furtherance of this mandate, the issue of GHG emissions from ships was first raised at the IMO in 1997.91 The first step by the Organization was to undertake a study on GHG emissions from ships.92 This initiative was followed by a resolution on ‘IMO Policies and Practices Related to the Reduction of Greenhouse Gas Emissions from Ships’, stressing the pre-eminent role of the IMO in addressing GHG emissions from ships in cooperation with the UNFCCC.93 The resolution also urged ‘the [MEPC] to identify and develop the mechanism or mechanisms needed to achieve the limitation or reduction of GHG emissions from international shipping’.94

Only gold members can continue reading. Log In or Register to continue