Image Image Image Image Image Image Image Image Image Image

International Windship Association | June 16, 2024

Scroll to top


Does It Pollute?

  • On March 3, 2015

Currently, the most official/authoritative emissions numbers are from the Third IMO Greenhouse Gas Study 2014.

IMO Executive Summary
IMO Full Report

The shipping industry has been mandated to invest in increased fleet efficiency via EEDI, however ‘slow steaming’ has been the sector’s principle method for emission reduction, especially in larger vessels. According to the IMO, over the period 2007-2012, the average reduction in at-sea speed relative to design speed was 12% and the average reduction in daily fuel consumption was 27%. However the reduction in speed and the associated reduction in fuel consumption do not relate to an equivalent percentage increase in efficiency, because a greater number of ships (or more days at sea) are required to do the same amount of transport work.

The emission reductions from slow steaming are not ‘locked in’ through technical improvements, therefore as fuel costs fall, there is less incentive to adopt slow steaming, speeds increase and emissions rise.

Summary of Key Points taken from Third IMO GHG Study 2014

For the period 2007–2012, on average, shipping (as a whole) accounted for approximately 3.1% of annual global CO2 and approximately 2.8% of annual GHGs on a CO2 equivalency basis.

International shipping accounts for approximately 2.6% and 2.4% of CO2 and GHGs on a CO2 equivalency basis, respectively.

NOx and SOx

Global NOx and SOx emissions from all shipping represent about 15% and 13% of global NOx and SOx emissions from human activity. International shipping NOx and SOx represent approximately 13% and 12% of global NOx and SOx totals, respectively.

Fuel Consumption

Average annual fuel consumption (2007-2012) ranged between approximately 250 million and 325 million tonnes of fuel consumed by all ships. International shipping fuel consumption ranged between approximately 200 million and 270 million tonnes per year.

CO2 Emissions

CO2 emissions from shipping are estimated to range between approximately 740 million and 795 million tonnes per year (or between approximately 900 million and 1150 million tonnes per year in bottom-up results). International shipping CO2 estimates range between approximately 595 million and 650 million tonnes (or between approximately 775 million and 950 million tonnes according to bottom-up results).

International shipping is the dominant source of the total shipping emissions of other GHGs: nitrous oxide (N2O) emissions from international shipping account for the majority (approximately 85%) of total shipping N2O emissions, and methane (CH4) emissions from international ships account for nearly all (approximately 99%) of total shipping emissions
of CH4.

Future scenarios (2012–2050)

Maritime CO2 emissions are projected to increase significantly in the coming decades. Depending on future economic and energy developments, this study’s BAU scenarios project an increase by 50% to 250% in the period to 2050.

Further action on efficiency and emissions can mitigate the emissions growth, although all scenarios but one project emissions in 2050 to be higher than in 2012.

Emissions projections demonstrate that improvements in efficiency are important in mitigating emissions increase. However, even modelled improvements with the greatest energy savings could not yield a downward trend. Compared to regulatory or market-driven improvements in efficiency, changes in the fuel mix have a limited impact on GHG emissions, assuming that fossil fuels remain dominant.

Most other emissions increase in parallel with CO2 and fuel, with some notable exceptions:

(i) Methane emissions are projected to increase rapidly (albeit from a low base) as the share of LNG in the fuel mix increases.

(ii) Emissions of nitrogen oxides increase at a lower rate than CO2 emissions as a result of Tier II and Tier III engines entering the fleet.

(iii) Emissions of particulate matter show an absolute decrease until 2020 and sulphurous oxides continue to decline through 2050, mainly because of MARPOL Annex VI requirements on the sulphur content of fuels.

Extracts taken from :Third IMO GHG Study 2014; International Maritime Organization (IMO) London, UK, June 2014; Smith, T. W. P.; Jalkanen, J. P.; Anderson, B. A.; Corbett, J. J.; Faber, J.; Hanayama, S.; O’Keeffe, E.; Parker, S.; Johansson, L.; Aldous, L.; Raucci, C.; Traut, M.; Ettinger, S.; Nelissen, D.; Lee, D. S.; Ng, S.; Agrawal, A.; Winebrake, J. J.; Hoen, M.; Chesworth, S.; Pandey, A.
Health Impact

Headline economic figures – €53.6 billion in socio-economic losses from health damage (2006 prices). This is the estimated cost of health effects in Europe alone from Shipping emissions in 2011 made in the report – CLEANER SHIPPING: focus on air pollution, technology and regulation.
Released by the Danish Eco Council