Discharges from Ships in the Arctic

(from AMSA Report 2009)


Accidental Discharges from Ships

The accidental release of oil or toxic chemicals can be considered one of the most serious threats to Arctic ecosystems as a result of shipping. The release of oil into the Arctic environment could have immediate and long-term consequences. Some Arctic animals are particularly sensitive to oil because it reduces the insulating properties of feathers and fur and they can quickly die from hypothermia if affected. This is the case for seabirds, including eiders and other sea ducks, and also polar bear and seal pups. Concentrated aggregations of birds and mammals, often in confined spaces such as leads and polynyas, increase the risk to the animals in the case of an oil spill in the Arctic. Crude and refined oils, including fuel oils used by ships, vary much in their physical and chemical properties. This, in addition to other factors such as temperature, light, waves and ice, plays a major role in the behavior of oil in the environment and the extent of biological effects.

Other potential problems from released oil include the transfer of oil to nests by sea birds landing on oil slicks and the ingestion of oil by animals while preening. This can lead to death or other biological effects both in the short and long term. Even small spills can have large consequences if they occur where marine birds are concentrated.

Chronic seepage of residual oil after a spill can affect the entire food chain in an area because hydrocarbons are taken up by bottom feeding invertebrates, which then end up as prey for sea birds and other animals, causing effects higher up the food web. Arctic animals are also particularly vulnerable to spills in certain areas and at certain times of the year when animals aggregate in large numbers to breed, nest, bear young and molt.

The Arctic is an extreme environment with a range of weather, light, hazards and with little human infrastructure. Responding to oil spills in these conditions is a major challenge, especially where ice is present. There are currently limited methods for recovering spilled oil in an ice-covered environment. The options currently available for oil spill recovery in the Arctic include mechanical methods, bio-remediation, dispersants and/or in-situ burning. Consequently, strong prevention measures must be of primary concern, while response measures, being both unreliable and untested, should be secondary. The risk of accidental release of oil and other contaminants increases with any increase in shipping activity that involves the use or transportation of oil or other chemicals.

Regular Ship Discharges to Water

As a part of normal operations, ships produce a range of substances that must eventually be eliminated from the ship through discharge into the ocean, incineration or transfer to port-based reception facilities. Referred to as regular discharges these include oil, ballast water, bilge water, tank washings (oily water), oily sludge, sewage (black water), garbage and grey water. Regular ship discharges are regulated through the IMO’s International Convention for the Prevention of Pollution from Ships, 1973, as Modified by the Protocol of 1978 Relating Thereto (MARPOL 73/78) and other IMO conventions, as well as through domestic regulation by coastal states. MARPOL has effectively reduced pollution in the marine environment by regulating the release of regular discharges. However, it has not eliminated discharges into the world’s oceans altogether.

Oil is released with bilge water with a maximum allowed concentration of 15 parts per million (15 mg per m3) after treatment with an oil separator. Oil is also released with water used for tank washings after required treatment and with restrictions on amount and rate of release to avoid formation of oil film at the surface (i.e., blue shine). Oily sludge, consisting of high molecular hydrocarbon substances, accumulates in fuel tanks in fairly large amounts, constituting typically 1-5 percent of the amount of fuel consumed. Oily sludge must not be released but stored on board and brought to reception facilities in ports.

A recent study of regular discharges from ships in the Norwegian and Barents seas provides an example of the level of discharge expected to be released in an area that has some of the heaviest ship traffic in the Arctic or subarctic region. In this study it was estimated that the amount of oil released via bilge water and tank washings that the MARPOL allowed 15 ppm totaled about two tons of oil per year, a relatively small amount. However, the study found ship operations generate about 13,000 metric tons of oily sludge annually.

The amount of legally discharged oil under MARPOL in the Norwegian study indicates that current amounts of legally discharged oil should not pose a significant threat to the local ecosystem so long as the laws are strictly followed. MARPOL requires oily sludge to be disposed of in port-based reception facilities. Norway is unusual in the Arctic region in that it has good port reception facilities in all of its Arctic ports, but that is not the case in many other areas of the Arctic. In some areas, limited port side infrastructure as well as the cost of disposing of waste using port reception facilities, provide incentive for illegal dumping of wastes produced on board.

Considering the sheer volume of oily sludge produced in Norwegian waters alone, it would take only a small percentage of the oily sludge produced to be illegally discharged for it to cause environmental damage. Illegal release of oil and oily sludge can cause oiling of animals and birds can be toxic to marine and terrestrial ecosystems and extremely difficult to clean up. Contamination can last for years in ocean sediment and other compartments of the marine environment, sometimes presenting contaminated prey upward within marine and coastal food chains. Oily sludge is not the only regular discharge that can end up in the ocean. Under MARPOL it is legal to discharge garbage and raw sewage into the water once a ship is a certain distance from shore. The presence of significant amounts of garbage and other debris in the ocean can result in a number of environmental impacts. These range from damage to marine habitat, entanglement of wildlife, introduction of bacteria and disease (from untreated human sewage) and the ingestion of plastics and other unsuitable items by marine mammals and birds. As vessel activity increases in the Arctic, the management of regular discharges from all vessels will need to be seriously considered so that environmental impacts are minimized.

Ship Emissions to Air

Studies assessing the potential impacts of international shipping on climate and air pollution demonstrate that ships contribute significantly to global climate change and health impacts through emission of GHGs (for example, carbon dioxide CO2, methane CH4, chlorofluorocarbons CFC), aerosols, nitrogen oxides (NOx), sulfur oxides (SOx), carbon monoxide (CO) and particulate matter (PM). Air quality impacts may result from the chemical processing and atmospheric transport of ship emissions. For example, NOx emissions from ships can combine with hydrocarbons in the presence of sunlight to produce ozone pollution, which can potentially affect visibility through haze, human and environmental health and has been associated with climate change effects.

The AMSA has developed the world’s first activity-based estimate of Arctic marine shipping emissions using empirical data for shipping reported by Arctic Council member states. Emissions were calculated for each vessel-trip for which data was available for the base year 2004. The 515,000 trips analyzed represent about 14.2 million km of distance traveled (or 7.7 million nautical miles) by transport vessels; fishing vessels represent over 15,000 fishing vessel days at sea for 2004. Some results could be an underestimation of current emissions, given potential underreporting bias and anecdotal reports of recent growth in international shipping and trade through the Arctic. Researchers at DNV recently completed a similar activity based emissions inventory for Norwegian waters (Operational emissions to air and sea from shipping activities in Norwegian Sea areas. DNV Report No. 2007-2030). A review and comparison of the DNV results with the Norwegian portion of the AMSA results showed good agreement for all vessel types, except for general cargo and fishing vessel estimates. The AMSA results for Norway were sometimes greater than, and sometime less than, the DNV results, generally falling within 10 percent to 30 percent confidence. The AMSA evaluates ship emissions of greenhouse gases and air quality pollutants that may have regional or local impacts; however it does not directly conduct the detailed studies needed to determine the level of impact (Table 2).

Results show CO2 emissions from international shipping in the Arctic region to be approximately 10,800 kilo tons per year tons (kt) CO2 per year. Given that total CO2 emissions from international shipping globally are about 1,000 MMT CO2 per year, Arctic contributions for 2004 amount to about 1 percent of total ship CO2 emissions, not an amount that would cause significant effects in the global context. However, pollutants such as black carbon (BC), particulate matter, nitrogen oxide (NOx), carbon monoxide (CO) and sulfur oxide (SOx), which may be small contributors to global inventories on a mass basis, may have regional effects even in small amounts. Current IMO regulations under MARPOL Annex VI that place requirements on the sulfur content of marine fuels, once implemented, will dramatically reduce SOx emissions from global shipping. As a result, observable impacts from SOx should decline and there may be indirect effects on the climate forcing properties of other air pollutants such as NOx and BC.

Black carbon is a component of particulate matter produced by marine vessels through the incomplete oxidation of diesel fuel. The release and deposition of BC in the Arctic region is of particular concern because of the effect it has on reducing the albedo (reflectivity) of sea ice and snow. When solar radiation is applied, reduced albedo increases the rate of ice and snow melt significantly, resulting in more open water, and thereby reducing the regional albedo further. In the Arctic region in 2004, approximately 1,180 metric tons of black carbon was released, representing a small proportion of the estimated 71,000 to 160,000 metric tons released around the globe annually. However, the region-specific effects of black carbon indicate that even small amounts could have a potentially disproportionate impact on ice melt and warming in the region. More research is needed to determine the level of impact this could have on ice melt acceleration in the Arctic and the potential benefits from limiting ships’ BC emissions when operating near to or in ice-covered regions. The potential impacts of black carbon should also be a point of consideration when weighing the costs and benefits of using in situ burning of oil in spill response situations.

As part of the AMSA emissions inventory, the amounts of carbon dioxide and black carbon emitted were mapped using the GIS database of shipping routes and areas of fishing vessel activity reported by Arctic states (Map 8.1).

The CO2 emitted by all vessels was mapped according to the location of activity; emissions from transport vessels (non-fishing vessels) were assigned to reported routes and fishing vessel emissions were assigned to the Large Marine Ecosystem in which the fishing fleet operated. The map shows that the heaviest CO2 and black carbon emissions were found in the Bering Sea region, around Iceland, along the Norwegian coast and in the Barents Sea. There are also moderate emissions along the western coast of Greenland.

Table 1:  A range of potential environmental impacts linked to ship types operating in the Arctic

Note: All ships will have certain impacts linked to the release of grey water, sewage, ballast and bilge water; air emissions; regular and accidental discharge of fuel/oil; introduction of noise and other acoustics such as sonar; and possible strikes on animals. Those listed above are in addition to these and specific to the vessel type. Source: AMSA

  1. Ship Category: Government Vessels and Icebreakers

Ship Sub-Category/Use: Coast guard vessels, research icebreakers, private icebreakers, government icebreakers, other research vessels)

Ship Type-Specific Pollution Sources: Accident/incident recovery-produced contaminants; emergency dumping oil/fuel; nuclear icebreaker radiation contamination; explosives/munitions; impacts due to

Ice-breaking activity (disruption of ice formation, marine mammals, etc.)

  1. Ship Category: Container Ships

Ship Sub-Category/Use: Cargo transport

Ship Type-Specific Pollution Sources: Hazardous goods in transit; convoy collision hazard; grounding hazard (uncharted waters, lack of experienced ice navigation).

  1. Ship Category: General Cargo

Ship Sub-Category/Use: Community re-supply vessels, roll on/roll off cargo.

Ship Type-Specific Pollution Sources: Hazardous goods in transit; accidental cargo release; contaminated cargo.

  1. Ship Category: Bulk Carriers

Ship Sub-Category/Use: Timber; merchant; oil; ore; automobile carriers

Ship Type-Specific Pollution Sources: Release of metal contaminants; radiation contamination from cargo; hazardous goods in transit.

  1. Ship Category: Tanker Ships

Ship Sub-Category/Use: Oil tankers; natural gas tankers; chemical tankers.

Ship Type-Specific Pollution Sources: Liquid Nitrogen Gas contamination; chemicals and hazardous goods in transit; spills from oil transfer.

  1. Ship Category: Passenger Ships

Ship Sub-Category/Use: Cruise ships; ocean liners; ferries.

Ship Type-Specific Pollution Sources: Large volumes of black and grey water release; garbage disposal; cleaning contaminants; disturbance of wildlife through viewing activities; automotive contaminants w/vehicles ferries.

  1. Ship Category: Tug/Barge

Ship Sub-Category/Use: Re-supply vessels; bulk cargo transport

Ship Type-Specific Pollution Sources: Increased accident hazard (non-propelled); hazardous goods in transit; spills during oil transfer, heavy emitters of air contaminants (black carbon).

  1. Ship Category: Fishing Vessels

Ship Sub-Category/Use: Small fishing boats; trawlers; whaling boats; fish processing boats.

Ship Type-Specific Pollution Sources: Increased fire hazard; introduction of pathogens and other contaminants from released fish offal; accidental release of invasive species/related biological contaminants; release of plastics; ghost nets and other fishing debris; seafloor damage from bottom

trawlers; depletion of marine species (if not managed); accidental release of refrigerant contaminants.

  1. Ship Category: Oil and Gas Exploration/Exploitation Vessels

Ship Sub-Category/Use: Seismic exploratory vessels; oceanic and hydrographic survey vessels; oil drilling vessels; oil and gas storage vessels; offshore re-supply; portable oil platform vessels; other oil and gas support vessels.

Ship Type-Specific Pollution Sources: Hazardous cargo; explosives; acoustic impacts from seismic activities; oil/hydrocarbon contamination; contamination from extraction chemicals; accidental loading/offloading spillage; fire hazards.

Table 2:  Estimated emissions in the Arctic for 2004 by ship type

Emission amounts were calculated using the AMSA marine activity database, which is based on information reported by Arctic Council member states. Baseline information was provided in different formats and to different degrees of detail between states.

(1)A review and comparison of the AMSA estimated fuel use by General Cargo vessels with recent activity-based inventories completed by Norwegian researchers at DNV suggest that this category may be overestimated, due to the world fleet characteristics for general cargo ships reflecting larger vessels with more installed power than typical for Arctic operations.

(2)A review and comparison of the AMSA Fishing vessel data with more direct activity-based estimates completed by DNV for Norwegian fishing vessels suggests that this first estimate may be in the range of three to four times higher than what was found by DNV. This is likely because the AMSA fishing vessel estimates are based primarily on days at sea, which assumes the vessel engine runs at varying capacity for the entire period at sea and may overestimate fishing vessel emissions and fuel use. Source: AMSA

Vessel Category:



General Cargo

Government Vessel

Other Service Vessel

Passenger Vessel


Tug & Barge



Fuel Use (kt/y):











CO2 (kt/y):











BC (t/y):











NOx (kt/y):











PM (kt/y):











SOx (kt/y):











CO (kt/y):














  •  1. Arctic Marine Shipping Assessment Report 2009

Arctic Council, 2009, Arctic Marine Shipping Assessment (AMSA), Arctic Council.©

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