Memorandum submitted by Alice Bows, Tyndall Centre, MACE, University of Manchester (EFS03)

The points made within this evidence are based on ongoing preliminary research into the UK's shipping industry and associated emissions, being carried out as part of the Tyndall Centre's core research programme at the University of Manchester. Much of the evidence is based on qualitative interviewing, and is therefore gathered through dialogue with shipping industry stakeholders. This evidence will, in some cases, require further quantitative research to add weight to the arguments made.

For the UK Government to assess its contribution to global climate change, it is essential to be able to account for all emission producing sectors. It is clearly more straightforward to do this for some sectors than others, however given the scale of the global climate change challenge faced (Anderson and Bows, 2008), calculating all of the emissions being generated to high precision is likely to be unnecessary. Rather, it is important that any method of apportioning emissions to the UK for the more 'international' sectors; such as aviation and shipping, aggregates to the global level. In other words, if the sum of all national emissions apportioned through a particular method does not at least approximate to the global total, the method will not be consistent with the climate change target chosen.

At Tyndall Manchester, we have looked at what the impact of including a 'fair' proportion of emissions from the international aviation and shipping industries has on the UK's carbon budget (Anderson and Bows, 2007; Anderson et al., 2008). Within the Anderson et al. paper published in Energy Policy, an estimate for the UK's shipping CO2 emissions was made, based on a crude method apportioning the global figure for international marine bunker fuel sold, using the UK's proportion of total global GDP. The estimate for CO2 from shipping for 2005 was ~20MtCO2 (compared with 35MtCO2 from aviation) - see table 2 within the paper; an estimated 3% of total UK CO2 emissions when including land use and forestry. However, this estimate is also based on a relatively low assumption for global marine bunker fuel, around 520MtCO2, similar to figures published by (Endresen et al., 2004) which are considerably lower than many other estimates for example (Corbett and Kohler, 2003; Eyring et al., 2005)). If one of the higher figures of 800MtCO2 is taken, then the UK's shipping contribution increases to 30MtCO2 (5% of the UK total) using this GDP-based method.

Although the bunker fuel consumed is often recorded by ship operators, a transparent method through which the data can be collated and used by governments is not currently operational. Understanding more clearly this total global marine bunker fuel figure will greatly assist in the calculation of national emission budgets.

How significant is global shipping's contribution to climate change?  How is this projected to change in the future?

The global shipping industry represents a considerable contribution to climate change; due to the very high percentage of goods transported world-wide for industrial and public consumption, coupled with a reliance on heavy fuel oil. Currently, attempts at estimating the CO2 emissions from global shipping have been subject to considerable uncertainty. Figures vary from study to study depending on the method used to make the estimation. The table below summarises some of the estimates available:


Total fuel consumed in 2000/1 international bunkers (Mtons)

Total CO2 emissions (MtonsCO2)

Baseline year

Method employed

Endresen (2003)




Bottom up indirect modelling based on engine type, routes, activity

Corbett (2003)




Bottom up approach independent from fuel sales statistics

Corbett (2004)




Bottom up approach independent from fuel sales statistics and updated from 2003

Eyring (2005)




Bottom up approach independent from fuel sales statistics and updated from Corbett in 2004

Endersen (2007)




Activity and fuel-based estimates

IMO expert group (2008)


~1125 but 867 if international only



National Techincal University of Athens (2008)




Bottom up approach incorporating the development of a web-based tool for calculating CO2 emissions and involving industry data

IEA marine bunker sales




Based on international fuel sales

The proportion of total global CO2 emissions for shipping, if calculated using a top-down method, depends on a reliable global CO2 emission figure. According to CDIAC, global CO2 from fossil fuels is estimated to be some 30GtCO2[1] in 2006, therefore shipping accounts for between 3%-4% of this, depending on which estimate is used.

Clearly, shipping is a very efficient mode of transportation considering the amount of freight moved globally. However, the global shipping industry is expected to continue to grow. Given the very limited global carbon budget available (Anderson and Bows, 2008), if the UK Government is to play its part towards a 2C target, curbing emission growth, and ultimately reducing the CO2 from shipping is desirable.

How should the UK's share of international maritime emissions be measured and included in UK carbon budgets?  How fast could this be done?

Currently the UK's share of international maritime emissions is based on the sales of bunker fuels. If this figure is divided per head for the UK and compared with the similar figure for the Netherlands, using this method, Dutch consumers appear to be using 28 times more bunker fuel per head. Clearly, this method of allocation is unreasonable. There are a number of methods for apportioning shipping emissions to the UK, with no single method likely to appeal to all parties. However, the method should respect the following criteria:

1) The method should ensure that if it is applied to all nations, the aggregate is equal to the global sum of CO2 emitted by world-wide shipping.

2) Reflect the UK's shipping activity rather than arbitrary fuel sales.

3) Where possible, be based on actual fuel consumed rather than modelled data.

Possible methods of apportionment that could aggregate on a global scale include:

- Allocation based on the UK's proportion of global GDP applied to global bunker fuel data: n.b. the figure obtained will depend heavily on the global bunker fuel figure recorded which is subject to great uncertainty - see (Corbett and Kohler, 2003; Eyring et al., 2005) (see table).

- Allocation based on the actual fuel consumed by incoming or outgoing ships docking at UK ports (avoiding double counting).

- Allocation based on a percentage share of global bunker fuel derived from the total freight-tonne-km associated with incoming or outgoing ships docking at UK ports (avoiding double counting).

- Allocation based on a percentage share of global bunker fuel derived from the total freight-tonnes associated with incoming or outgoing ships docking at UK ports (avoiding double counting).


Possible method of apportionment that will not aggregate on a global scale is:

- Allocation based on a particular geographical location - i.e. all emissions within 100 miles of UK ports.

To incorporate shipping into UK carbon budgets, it is firstly essential that the UK's budget reflects the UK's climate change target (2C), and begins with a total that reflects not only the UK's domestic CO2 emissions, but also emissions from international aviation and shipping. This is a critical point, as the higher the starting total, the more rapidly the UK's carbon budget will be consumed. See (Anderson et al., 2008) and (Anderson and Bows, 2007) for more details.

According to industry stakeholders, ship crew record fuel consumed on each journey, but the information is not publically available for various administrative and competitive reasons. In addition, Lloyd's register includes a variety of data on the global shipping industry. Given the data is already collated at this level, a first step in measuring CO2 associated with UK shipping would be to work through the UK Chamber of shipping, the various ports associations to develop a method for facilitating the collation of this data for the purposes of UK CO2 inventories.

What are the prospects of international agreements to control and reduce carbon emissions from global shipping, or to bring it within wider emissions trading schemes?  How well is the UK Government playing a role in developing such agreements?

My understanding is that the IMO decision-making process is very slow due to its organisational arrangements. However, the pressure of knowing the EU is likely to regulate in the form of emissions trading, has somewhat accelerated discussions. Most importantly, any international agreement to control and reduce carbon emissions from global shipping must take account of the underlying evidence base linking emission pathways with 2C. See Anderson, Bows & Mander 2008 and Anderson & Bows 2008 below for further details.

What are the prospects for developing new engine technologies and fuels, as well as more fuel-efficient operations?  What more could the Government do to assist these developments?

In relation to more fuel efficient operations, ports have a role to play in smooth throughput of the loading and unloading of ships. On many occasions, ships travel quickly to reach a destination, only to find they must then queue for several days to unload. In other words, ships have used more fuel in the transit than necessary; as the relationship between fuel burn and speed is a cubed law. I.e. speed is proportional to the cube of fuel consumed. If there were a mechanism by which port operations could be managed more efficiently, to ensure ships could know well in advance when the next available slot for unloading or loading might be, shipping speeds and hence fuel burn may be reduced. More research needs to be carried out in this area to overcome the current constraint of inefficient port operations.

Anderson, K. and A. Bows, 2007. A response to the Draft Climate Change Bill's carbon reduction targets. Tyndall Centre Briefing Note 17, Tyndall Centre for Climate Change Research, from

Anderson, K. and A. Bows, 2008. Reframing the climate change challenge in light of post-2000 emission trends. Philosophical Transactions A. In press.

Anderson, K., A. Bows and S. Mander, 2008. From long-term targets to cumulative emission pathways: Reframing UK climate policy. Energy Policy. In Press, Corrected Proof.

Corbett, J. J. and H. W. Kohler, 2003. Updated emissions from ocean shipping. Journal of Geophysical Research. 108,(D20, 4650).

Endresen, O., E. Sorgard, J. Bakke and I. S. A. Isaksen, 2004. Substantiation of a lower estimate for the bunker inventory: Comment on "updated emissions from ocean shipping" by James J Corbett and Horst W Koehler. Journal of Geophysical Research. 109,(doi:10.1029/2004JD004843), D23302.

Eyring, V., H. W. Kohler, J. v. Aardenne and A. Lauer, 2005. Emissions from international shipping: 1. The last 50 years. Journal of Geophysical Research. 110,(D17305).

September 2008

[1] This total will itself vary depending on the estimate used for the international bunker CO2