Black Carbon and Arctic Shipping

Background

Black carbon as a climate forcer

Black carbon is the strongly light-absorbing carbonaceous component of fine particulate matter (PM2.5), formed from the incomplete combustion of carbon-containing fuels (diesel, HFO, biomass, coal). It is a primary emission (formed during combustion, not from atmospheric chemistry) and is removed from the atmosphere by wet and dry deposition with an atmospheric lifetime of approximately 5 to 11 days.

The climate impact of BC comprises three principal mechanisms:

• Direct absorption: BC particles in the atmosphere absorb incoming solar radiation, warming the atmosphere directly.
• Snow and ice albedo reduction: BC deposited on snow or ice reduces the surface albedo (reflectivity), increasing absorption of incoming radiation and accelerating melt. This is particularly significant in polar regions where snow and ice cover are extensive.
• Cloud effects: BC interacts with cloud microphysics (cloud-drop nucleation, semi-direct effects, indirect effects) with both warming and cooling components; the net effect is uncertain but generally warming.

The 100-year global warming potential of BC is reported by various authorities at:

• IPCC AR5 best-estimate central value: approximately 900 (with uncertainty range 460 to 1,500 depending on study and methodology).
• Bond et al 2013 comprehensive synthesis: approximately 900 to 1,500.
• IPCC AR6 central value: approximately 1,000.

Because the GWP-100 of BC is so high, even small mass emissions translate to significant CO2eq impact. A typical Capesize bulker emitting 5 t-BC/year equates to approximately 4,500 to 7,500 t-CO2eq/year on the Bond et al basis, comparable in magnitude to the BC vessel’s annual CO2 emissions.

The GWP-20 of BC is significantly higher (approximately 3,200 best estimate), reflecting BC’s strong near-term warming impact relative to its short atmospheric lifetime. Policy discussions of BC frequently invoke GWP-20 to highlight the near-term Arctic warming consequence.

Marine BC emissions

Marine BC emissions vary by fuel type and by engine load. Typical emission factors (g-BC per kg-fuel) under steady-state operation:

The figures above are representative; significant variation is observed between engines, with engine wear, with operating profile, and with fuel composition. The ICCT (International Council on Clean Transportation) has compiled the most comprehensive marine BC emission inventory, used as the basis for IMO and EU policy discussions.

Hot-spot operating conditions

BC emissions are concentrated at certain operating conditions:

• Cold start: high BC during the warm-up period when cylinder walls are cold and combustion is incomplete.
• Low load: high BC at part load (typically 25 to 50% MCR) due to longer combustion duration and cooler cylinder temperatures.
• Transient operation: high BC during rapid load changes, particularly load increases.
• Aging engine: progressively higher BC as injection nozzles wear and combustion deteriorates.
• Poor fuel quality: HFO with high asphaltenes, high sulphur or high heavy-metals content tends to produce more BC than well-refined VLSFO or distillate.

For Arctic shipping, the time spent in port (cold-start emissions) and the tendency to operate at low to moderate load (manoeuvring through ice) means that the operational BC emission rate per kg-fuel is typically 30 to 60% higher than the steady-state design value.

The Arctic-specific concern

Arctic warming and the BC role

The Arctic is warming approximately 3 to 4 times faster than the global average (the “Arctic amplification”). The principal drivers of Arctic amplification are:

• Sea ice albedo feedback: as sea ice retreats, the darker ocean below absorbs more incoming radiation, accelerating warming and further sea-ice loss.
• Atmospheric water vapour and cloud feedbacks.
• Reduced atmospheric heat loss to space in the autumn, when warmer ocean retains heat longer.
• Black carbon deposition on snow and sea ice: BC deposition reduces albedo and accelerates melt.

The BC contribution to Arctic warming is estimated at approximately 17 to 25% of the total Arctic warming since 1900 (AMAP - Arctic Monitoring and Assessment Programme), making it the second-largest contributor after CO2 (approximately 60 to 70%).

Marine BC contributes a small but rapidly-growing share of total Arctic BC deposition, currently approximately 1 to 5% but projected to grow to 5 to 15% by 2050 if the Northern Sea Route (NSR) and Northwest Passage (NWP) traffic grows as forecast and if emission controls remain unchanged.

The Northern Sea Route

The Northern Sea Route (NSR) is the shipping route along the Russian Arctic coast from the Bering Strait to Murmansk. Annual transit traffic has grown from approximately 4 vessels in 2010 to approximately 30 to 40 transit vessels in 2024 (excluding the much larger Russian domestic shipping). Western sanctions on Russia following the 2022 Ukraine invasion temporarily reduced NSR traffic but recent quarters show recovery as Russian and Chinese-led traffic has substituted.

The NSR offers significant distance savings versus the Suez Canal route for trades between East Asia and Europe (approximately 40% reduction in voyage distance). The principal constraints on NSR uptake are: ice conditions (reliable ice-free transit only July to October), nuclear icebreaker escort fees, Polar Code compliance requirements, and political constraints associated with Russian sovereignty assertions.

The Northwest Passage

The Northwest Passage (NWP) through the Canadian Arctic Archipelago is shorter than the NSR and is open seasonally for approximately 8 to 10 weeks per year. Commercial traffic remains very limited (typically under 10 transits per year for cargo) due to the difficulty of ice navigation and the limited support infrastructure.

Arctic shipping growth projections

DNV’s Maritime Forecast to 2050 (2023) projects:

• NSR traffic: 50 to 200 transits per year by 2030, 200 to 800 by 2050.
• NWP traffic: 10 to 50 transits per year by 2030, 50 to 200 by 2050.
• Other Arctic traffic: cruise vessels, fishing vessels, scientific vessels, regional cargo. Significant growth driven by tourism and resource extraction.

The growth is sensitive to climate-warming pace (faster warming opens routes for longer per year) and to geopolitical conditions (Russia-NATO relations, China-Western relations, Arctic Council functionality).

Regulatory framework

Polar Code

The International Code for Ships Operating in Polar Waters (Polar Code), adopted by IMO Resolution MSC.385(94) and MEPC.264(68), entered into force on 1 January 2017. The Polar Code is a structured framework covering:

• Part I-A (Safety): mandatory safety provisions including ship structure, stability, machinery, fire safety, life-saving appliances, navigation, radio communication, voyage planning.
• Part I-B (Safety): recommendatory safety provisions.
• Part II-A (Environmental): mandatory environmental provisions covering oil discharge, noxious liquid substance discharge, garbage discharge.
• Part II-B (Environmental): recommendatory environmental provisions.

The Polar Code applies to vessels operating in Polar waters (defined as waters above 60° N for Arctic and 60° S for Antarctic, with some exceptions). Vessels are categorised as Category A (designed for ice up to 0.7 m thickness in winter), Category B (lighter ice) or Category C (occasional ice contact only).

The Polar Code includes a Polar Ship Certificate, a Polar Water Operational Manual, ice-strengthened hull requirements, additional life-saving equipment, voyage planning provisions, and crew training (additional STCW certification for ice navigation).

The Polar Code did not initially include BC controls; the BC discussion has been a parallel and ongoing IMO process.

MEPC 76 HFO Arctic ban (in force July 2024)

The 2021 MEPC 76 ban on HFO use and carriage as fuel in the Arctic (Resolution MEPC.329(76)) is the first major BC-relevant Arctic measure. Key provisions:

• HFO use ban from 1 July 2024: vessels are prohibited from using HFO as fuel in Arctic waters from 1 July 2024.
• HFO carriage as fuel ban from 1 July 2029: vessels are prohibited from carrying HFO as fuel in Arctic waters from 1 July 2029, with limited exemptions for vessels engaged in search and rescue operations.
• Limited exemptions through 2029 for certain vessels (notably some Arctic coastal-state-flagged vessels with HFO-only engines).
• Geographic scope: defined by latitude and specific exclusion zones; covers most of the Russian, Norwegian, Greenlandic and Canadian Arctic.

The HFO ban is principally an oil-spill-risk measure but has significant BC co-benefits because it forces a switch from HFO to MGO or distillate fuels with lower BC emission factors. The expected BC emission reduction from the HFO ban is approximately 30 to 50% on Arctic-operating vessels.

MEPC 84 BC measure (under negotiation 2025)

The IMO Pollution Prevention and Response Sub-Committee (PPR) and Marine Environment Protection Committee (MEPC) have been developing a comprehensive Arctic BC measure through 2018 to 2025. The measure under final negotiation at MEPC 84 (autumn 2025) is expected to:

• Set maximum BC emission limits by engine type and operating condition.
• Require continuous BC emission monitoring for vessels operating in defined Arctic areas.
• Require certification by the classification society of the BC emission performance.
• Incorporate the BC measure into MARPOL Annex VI Regulation 14 or as a new chapter.

The detail of the measure is still under negotiation. Key contested points include:

• Geographic scope: whether to apply only to “true Arctic” (above 70° N) or to all Polar waters (above 60° N).
• Engine retrofit requirements: whether to require retrofit of existing vessels or only to apply to newbuilds.
• Compliance flexibility: whether to permit emission averaging across vessels in a fleet, or to require per-vessel compliance.
• Distillate fuel mandate: whether to mandate distillate fuel use (which would force a more aggressive BC reduction) or to allow other compliance pathways.

The measure is expected to enter into force from approximately 2027 to 2029, depending on the timing of the MEPC adoption and the standard MARPOL Annex VI amendment process.

EU and US measures

The EU AFIR Regulation (Alternative Fuel Infrastructure Regulation) for shore power and the EU Deforestation-free Products Regulation indirectly affect Arctic shipping but do not specifically target BC.

The US Environmental Protection Agency (EPA) Tier 4 marine emission standards for new vessel engines (in force from 2014 for engines below certain size thresholds) include particulate matter (PM) limits that effectively control BC. The standards do not extend to large slow-speed two-stroke engines (which dominate the Arctic-operating cargo fleet).

The CARB (California Air Resources Board) rules apply within California state waters and do not extend to Arctic operations.

Voluntary frameworks

The Clean Arctic Alliance (a coalition of NGOs including FUTURE - Fund for the Environment, ICC - Inuit Circumpolar Council, Pacific Environment) has campaigned for Arctic BC controls and for HFO bans since approximately 2017. Several Arctic Council member states (Norway, Sweden, Finland, Canada, USA - inconsistently) have supported the Clean Arctic Alliance positions at IMO.

The Poseidon Principles and Sea Cargo Charter include BC in their environmental scoring but with relatively limited weighting compared to CO2.

Mitigation technologies

Distillate fuel

The simplest and most cost-effective BC mitigation is to switch from HFO or VLSFO to MGO or distillate fuel (LSMGO 0.1% S, ULSMGO 0.001% S). The fuel switch reduces BC emission factor by approximately 50 to 80% versus HFO, with no engine modification required.

The fuel cost premium of MGO vs HFO is typically USD 100 to USD 250/t (variable with crude oil and refinery margin). For an Arctic-operating Capesize bulker burning 35 t-fuel/day for 60 days/year in the Arctic, the additional fuel cost is approximately USD 200,000 to USD 500,000 per year.

Diesel particulate filter (DPF)

A diesel particulate filter is a ceramic or metal filter that physically traps particulate matter (including BC) in the exhaust stream. Marine DPFs are commercially available from several vendors (Boll Group, Hug Engineering, IBIDEN, Nett Technologies, NoNox) and achieve typical 90 to 99% BC reduction.

DPF performance and cost:

• BC reduction: 90 to 99%.
• Pressure drop: typically 1 to 3 kPa, equivalent to 0.5 to 1.5% additional fuel consumption.
• Sulphur sensitivity: requires LSMGO or ULSMGO operation; DPF lifetime is severely shortened by HFO or VLSFO operation.
• Capital cost: USD 100,000 to USD 400,000 per engine depending on engine power.
• Periodic regeneration: required to burn off accumulated soot; achieved by raising exhaust temperature (active regeneration) or by adding fuel-borne catalysts (passive regeneration).

DPFs are widely deployed on land-based heavy-duty diesel applications (trucks, locomotives) since approximately 2007. Marine DPF deployment is at approximately 50 to 200 vessels in 2024, principally smaller vessels operating in low-emission zones. Larger marine engines (slow-speed two-stroke) face more challenging DPF applications because the larger exhaust volumes require larger DPF systems.

Engine combustion redesign

Engine manufacturers have refined combustion design to reduce BC at source. The principal levers are:

• Higher injection pressure: better fuel atomisation reduces BC formation.
• Common-rail injection: variable injection timing and pressure permits optimisation across operating conditions.
• Multi-pulse injection: fuel injected in multiple pulses to allow better mixing.
• Combustion chamber geometry: chambers designed to maintain longer high-temperature residence reduce BC.

These approaches collectively reduce BC by approximately 20 to 50% versus older designs. Modern Tier III-compliant engines have lower BC emissions than older Tier I or Tier II engines, even before accounting for any aftertreatment.

LNG, methanol, ammonia conversion

The fundamental BC mitigation is to switch to a fuel that does not produce significant BC. LNG (essentially methane), methanol and ammonia all produce near-zero BC when properly combusted.

For Arctic operations, the conversion to LNG provides BC mitigation alongside the avoided HFO use under the 2024 ban. Arctic LNG bunker availability is currently limited (a small number of LNG bunker barges in Murmansk and Sabetta); expansion is ongoing.

For biofuels, particularly biodiesel (FAME) and hydrogenated vegetable oil (HVO), BC emissions are typically 20 to 50% lower than petroleum diesel due to the oxygen content of the biofuel improving combustion. Biodiesel blends are increasingly used as a partial BC mitigation.

Operational measures

Several operational measures reduce BC without hardware modification:

• Avoid low-load operation: BC is concentrated at part load. Operators can consolidate loads onto fewer engines at higher load.
• Avoid cold starts: significant BC is emitted during engine warm-up. Operators can use shore power (where available) or auxiliary heating to reduce cold-start emissions.
• Maintain engine condition: worn injectors and turbochargers increase BC. Regular maintenance reduces in-service BC.
• Use high-quality fuel: well-refined VLSFO with low asphaltene content produces less BC than poorly-refined HFO.

These measures collectively deliver 10 to 30% BC reduction; useful but not transformative.

Measurement methodology

Continuous BC monitoring

Marine BC measurement is more challenging than CO2 or methane measurement. The principal techniques are:

• Aethalometer (filter-based, light-absorption): collects soot on a filter and measures light absorption to derive BC mass. Established field instrument, moderate accuracy (± 20 to 30%).
• Single Particle Soot Photometer (SP2): laser-based incandescence measurement of single particles. High accuracy (± 5 to 10%) but high capital cost.
• Photoacoustic spectroscopy: laser-induced sound waves from absorbing particles. Moderate accuracy (± 15 to 25%).
• Multi-Angle Absorption Photometer (MAAP): another light-absorption approach.

The IMO PPR Sub-Committee has agreed (in principle) to use the filter smoke number (FSN) measurement as the basis for the upcoming Arctic BC measure, which can be converted to BC mass using established correlations. FSN measurement is straightforward and inexpensive, although less accurate than the laser-based methods.

Marine BC measurement instrumentation is commercially available from Aethlabs, Magee Scientific, AVL, Horiba and several other vendors.

Periodic spot measurement

For owners not investing in continuous monitoring, periodic spot measurement (typically annual, at the engine commissioning and at periodic surveys) is an alternative. The IMO BC measurement protocol (in development) defines the spot-measurement methodology.

Engine-modelled estimation

Engine-modelled estimation of BC from engine bench-test data combined with operating profile is the lowest-cost approach but lowest-accuracy.

Implications for Arctic-operating owners and charterers

Owners

Owners of Arctic-operating vessels face a regulatory environment that is rapidly tightening: the 2024 HFO ban, the 2029 HFO carriage ban, and the upcoming MEPC 84 BC measure. The principal owner decisions are:

1. Fuel switch: from HFO to MGO/distillate is the most immediate compliance step. Cost: USD 100,000 to USD 500,000 per Arctic season per vessel.
2. DPF retrofit: 90 to 99% BC reduction, USD 100,000 to USD 400,000 per engine plus operational costs. Decision sensitive to the final form of the MEPC 84 BC measure.
3. LNG conversion: most aggressive BC mitigation but USD 5 to USD 30 million per vessel for conversion. Justified for vessels with significant Arctic operating profile.
4. Polar Code compliance: ongoing requirement for ice-strengthened hull, ice navigator certification, additional safety equipment.
5. Charter avoidance: some owners may exit the Arctic charter market if compliance costs exceed the freight premium.

Charterers

Arctic charterers (notably Russian-based oil and gas exporters, Chinese state importers, and a small number of European bulk shippers) face indirect cost passthrough as owner compliance costs increase. The charter premium for Arctic operations is being discounted upward to reflect the new costs.

Insurers

Marine insurers (P&I clubs and hull underwriters) have begun applying Arctic-specific premiums reflecting the elevated environmental and reputational risk of Arctic shipping. The combination of Polar Code compliance, BC controls, and the broader oil-spill risk drives the Arctic premium structure.

Banks and finance

Ship-finance banks signed up to the Poseidon Principles report Arctic shipping exposure separately as part of their portfolio reporting, reflecting the elevated climate-impact-per-fuel-burnt of Arctic operations.

Future outlook

MEPC 84 outcome

The outcome of MEPC 84 (autumn 2025) on the Arctic BC measure is the principal near-term development. The expected outcome is adoption of a measure for inclusion in MARPOL Annex VI, with entry into force from approximately 2027 to 2029. The detail of the measure (geographic scope, engine retrofit requirements, distillate fuel mandate) will significantly affect the implementation cost.

Continued NSR growth

If geopolitical conditions permit (Russia-China cooperation continues, Western sanctions ease), NSR traffic may grow more rapidly than the DNV central case, increasing the Arctic BC concern. The Arctic Council framework (currently impaired by Russia’s exclusion) is the principal multilateral forum for managing the growth.

Additional Arctic protections

The Clean Arctic Alliance and several Arctic Council member states are advocating for additional Arctic-specific protections including:

• Heavy fuel oil ban for transit through the Arctic (extending the use ban to include transit-only vessels).
• Speed limits in defined Arctic areas to reduce both BC emissions and underwater noise.
• Mandatory pilotage in defined Arctic areas.
• Ban on HFO carriage as cargo through Arctic (currently the ban is for fuel only, not for cargo).

Convergence with greenhouse-gas frameworks

The Arctic BC measure is being developed in parallel with the IMO Net-Zero Framework and the FuelEU Maritime frameworks, both of which are CO2-focused. Integration of BC into the GHG frameworks (using a GWP-100 of approximately 900) would significantly increase the policy weighting of BC and would likely accelerate fleet-wide BC mitigation.

See also

Marine fuels

• LNG as marine fuel
• LNG fuel system
• Methanol as marine fuel
• Ammonia as marine fuel
• Biofuels in shipping
• Heavy fuel oil
• Marine gas oil
• Well-to-wake intensity
• RFNBO under EU rules
• Methane slip from LNG dual-fuel
• N2O emissions from marine engines

Engines, exhaust and machinery

• Marine diesel engine
• Marine gas turbine
• Marine propeller
• Exhaust gas cleaning system
• Bow thruster and stern thruster

Regulatory and reporting frameworks

• MARPOL Annex VI
• IMO Net-Zero Framework
• IMO GHG Strategy
• EEXI, EPL and ShaPoLi
• SEEMP I, II, III
• CII corrective action plan
• EU MRV Regulation
• EU ETS for shipping
• FuelEU Maritime
• FuelEU penalties, pooling and multipliers
• UK ETS for shipping
• China DCS
• IMO DCS vs EU MRV
• CARB at-berth rule
• Emission control areas
• NOx Tier I, II, III
• IMO 2020 sulphur cap

Voluntary frameworks

• Poseidon Principles
• Sea Cargo Charter
• RightShip GHG Rating
• Green Shipping Corridors
• BIMCO CII clauses
• EUA market mechanics for shipping
• Voluntary carbon credits in shipping

Operational and technical efficiency

• Wind-assisted propulsion
• Air lubrication systems
• Just-in-time arrival
• Weather routing
• Trim optimisation
• Slow steaming
• Bulbous bow retrofits
• Energy-saving devices
• Battery-hybrid propulsion
• Onboard carbon capture
• Cold ironing / shore power

Hydrostatics, stability and ship types

• Hull form design
• Block coefficient
• Hydrostatics and Bonjean curves
• Trim and list
• Metacentric height
• Free surface effect
• Intact stability
• Damage stability
• Ship resistance and powering
• Bulk carrier
• Container ship
• Chemical tanker
• LNG carrier
• General cargo ship

Conventions, codes and class

• SOLAS Convention
• MARPOL Convention
• Ballast Water Management Convention
• Hong Kong Convention
• COLREGs Convention
• ISM Code
• ISPS Code
• Classification society

Calculators

• Black carbon emission factor calculator
• Arctic BC deposition calculator
• BC GWP equivalency calculator
• DPF retrofit savings calculator
• Polar Code compliance calculator
• WtW intensity calculator
• GFI compliance calculator
• SEEMP Measures Combined calculator
• EEXI Required calculator
• CII Attained calculator
• Calculator catalogue

References

• IMO Resolution MEPC.329(76): Amendments to MARPOL Annex I (HFO use and carriage in the Arctic). International Maritime Organization, 2021.
• IMO Resolution MSC.385(94) and MEPC.264(68): International Code for Ships Operating in Polar Waters (Polar Code). International Maritime Organization, 2014/2015.
• IMO PPR 9 and PPR 10: Outcome documents on the development of the Arctic black carbon measure. International Maritime Organization, 2022/2023.
• Bond, T. C. et al. Bounding the role of black carbon in the climate system: A scientific assessment. Journal of Geophysical Research, 2013.
• AMAP. Arctic Climate Change Update 2021: Key Trends and Impacts. Arctic Monitoring and Assessment Programme, 2021.
• ICCT. Black Carbon Emissions from International Shipping. International Council on Clean Transportation, 2017.
• ICCT. Black Carbon Emission Inventory and Reduction Potential for the Arctic. International Council on Clean Transportation, 2022.
• Clean Arctic Alliance. The Need for an Arctic Black Carbon Standard. Clean Arctic Alliance, 2023.
• DNV. Maritime Forecast to 2050. DNV Energy Transition Outlook, 2023.
• IPCC. Sixth Assessment Report (AR6). Intergovernmental Panel on Climate Change, 2021/2022.

Further reading

• AMAP. Arctic Marine Ship-Source Pollution Assessment. Arctic Monitoring and Assessment Programme, 2024.
• US EPA. Arctic Black Carbon Strategy. United States Environmental Protection Agency, 2022.
• ICS. Catalysing the Fourth Propulsion Revolution. International Chamber of Shipping, 2022.
• IRENA. A pathway to decarbonise the shipping sector by 2050. International Renewable Energy Agency, 2021.

External links

• International Maritime Organization
• Arctic Council
• Arctic Monitoring and Assessment Programme (AMAP)
• Clean Arctic Alliance
• DNV Maritime
• Lloyd’s Register Marine
• International Council on Clean Transportation
• Inuit Circumpolar Council
• Pacific Environment
• Northern Sea Route Information Office
• European Commission Joint Research Centre