Committee on Climate Change

Global shipping emissions

Emissions from shipping currently account for 3% of total global emissions, (1.1 GtCO₂). They have increased rapidly in recent years, driven by growth in international trade, and are projected to grow by up to 3% per year from now to 2050.  Around 80% of shipping emissions are due to international shipping, and are therefore not included in country-level emissions inventories and associated emission reduction targets.

By 2050, CO₂ emissions from global international shipping could account for up to 25% of total fossil fuel CO₂ emissions consistent with achieving the climate objective underpinning the UK's Climate Change Act (2008). It is therefore important that these emissions are included in international strategies and agreements to reduce total emissions. 

International policy on shipping emissions

Ideally shipping emissions would be covered by a global agreement, for example through market based measures such as a global cap and trade scheme, or a carbon tax. This would provide incentives to reduce shipping emissions, and would help to tackle climate change. 

To date, however, despite the welcome agreement at the International Maritime Organisation (IMO) on the Energy Efficiency Design Index for new ships, there has been limited progress on developing market based measures. Progress has been slow as some countries have sought to prevent the application of measures which they deem to contravene the UNFCCC principle of common but differentiated responsibility, and the IMO principle of equal treatment.

Current UK shipping emissions

The current level of UK shipping emissions is highly uncertain, as there are a range of ways for estimating them and actual fuel use data from ships is not publically available. Currently, countries report shipping emissions based on the amount of fuel sold to shippers (‘bunker fuels’). However, at the UK level bunker fuels estimates are likely to be imperfect as a significant amount of UK trade is shipped via other ports where refuelling may take place.

Alternative top-down methods for calculating international shipping emissions allocate the UK a share of global international shipping emissions based on, for example, share of world trade. These produce a range for the UK of 12-29 MtCO₂ in 2006.  However, these methods are problematic because they are not derived from actual ship or cargo movements. 

The CCC has produced a bottom-up methodology which estimates UK shipping emissions on the basis of the miles travelled by, and the carbon intensity of, ships arriving at UK ports. This approach is aimed at estimating emissions more accurately, and also disaggregating them on the basis of the type of ship travelling. 

Using this methodology, we estimate that UK shipping emissions are currently in the range of 12-16 MtCO₂, but we cannot rule out that they are higher.

In our Review of UK Shipping Emissions we highlighted the need for Government to work with the EU and industry to access fuel consumption data held by ship operators. This would help resolve some of the uncertainty over the current level of emissions, and would be necessary to do before implementing any measures to limit shipping emissions, either at a regional or global level. 

Including international shipping emissions in the 2050 target and carbon budgets

It is crucial that international shipping emissions are, at some point, included in the UK’s 2050 target to reduce emissions by 80% on 1990 levels. This target was specifically designed to include international shipping emissions. Our projected international shipping emissions could account for a significant proportion of total allowed emissions under the 2050 target in the Climate Change Act:

• The emissions limit under the 2050 target to reduce emissions by 80% on 1990 levels is around 160 MtCO₂e.
• Our projected international shipping emissions of up to 18 MtCO₂ could account for up to 11% of total allowed emissions in 2050

This implies a tight limit on emissions for the rest of the economy, which becomes more pronounced when international aviation emissions are accounted for.

The Committee has set out three options for UK Government to consider on how international shipping emissions could be included in the UK climate targets: 

1. International shipping emissions are included in the 2050 target and carbon budgets now.
    
2. They are included in the 2050 target and carbon budgets when progress has been made on a methodology to accurately reflect international shipping emissions.
    
3. They are included in the 2050 target now, and in carbon budgets when progress has been made on a methodology to accurately reflect UK international shipping emissions.

The Committee will set out its views on which option would be most favourable in advice on the inclusion of international aviation and shipping emissions to be published in Spring 2012.