Can shipping emissions be kept in check in a post-COVID future?


By  – Tyndall Centre, University of Manchester

The shipping sector is playing a vital role in the COVID-19 pandemic, keeping Britain supplied with everything from pasta to PPE. But what role does it need to play in another great crisis – preventing catastrophic climate change?

Here, Simon Bullock from the Tyndall Centre, Manchester, looks at what needs to be done in order to keep shipping emissions below the 1.5 degrees Paris Climate Agreement.

  • International shipping emits more carbon dioxide than Germany
  • Ships used by the industry are likely to be in service for nearly 30 years
  • From this current infrastructure, the sector’s ‘committed emissions’ are enough alone to exceed the Paris Climate Agreement’s 1.5 degrees goal.
  • New research suggests that policy interventions on existing vessels could enable the shipping sector to meet the Paris targets, assuming that new vessels were also able to run on zero-carbon fuels from 2030.

Ships typically emit less carbon dioxide (CO2) per tonne of freight than lorries or planes. But the global impact of shipping is still huge: if it were a country, it would be the 6th highest emitter in the world. So what needs to be done?

New research from the Tyndall Centre explores this issue for shipping through the concept of “committed emissions”. Committed emissions are those emissions we can expect to see in years to come from existing infrastructure – in this case, existing ships that will continue to emit CO2 across their 30-year lifetime.

Our research considers ships travelling to and from the EU in 2018 – how much CO2 they are emitting, and how long they are likely to stay in service. The committed emissions just from these existing ships exceeds the amount of CO2 EU shipping is allowed to emit overall if it is to make a fair contribution to the Paris Climate Agreement’s goal to keep global warming below 1.5 degrees. Because ships have average lifetimes pushing three decades, it is existing ships, not new ships, that will be responsible for most of shipping’s future CO2 emissions. This is in contrast to the road transport sector, where there are shorter product lifetimes, and a much faster turn-over of the vehicle fleet.

But, there is hope. There are many ways in which emissions from existing ships can be cut: slower speeds, fitting modern sails, using green electricity when in port, retrofitting vessels to be more energy efficient, greater use of hybrid vessels using batteries, and retrofitting vessels to use zero-carbon fuels such as ammonia and hydrogen.

Our research shows that if new vessels are able to run on zero-carbon fuels from 2030, then a strong suite of policies targeting existing vessels – on speed, operational efficiencies, blended fuels and zero-carbon fuel retrofits – could keep shipping’s emissions within the Paris Agreement’s 1.5 degree carbon budget. But only if this action to retrofit the fleet happens quickly.

What needs to happen next?

First, the International Maritime Organisations (IMO) current target of at least 50% cuts in greenhouse gas emissions by 2050 needs to be significantly tightened to be compatible with the Paris 1.5 degrees goal. Our research indicates that keeping within 1.5 carbon budgets would need shipping CO2 emissions to fall to net-zero by 2040.

Second, the IMO’s policy focus is predominantly on measures for new ships, such as the Energy Efficiency Design Index (EEDI) energy efficiency policy, which sets emission levels per tonne km for new ships. While this and at-scale deployment of zero-emission fuels and ships by 2030 are both essential, it is critical that the IMO focusses on measures that cut emissions from existing ships as well, as existing ships will produce the bulk of future emissions. “Slow steaming” is one of the best short-term measures to cut energy use and emissions; ship operators still widely practice this since the financial crash, to cut fuel costs. This has cut the CO2 intensity of ships by 30% since 2008. Further savings are possible still but require some form of international policy mechanism. One problem is that progress at the IMO is mired in complex wrangles over policy design, with reluctance to make any measure mandatory. Breaking the international impasse on progress on slower-speeds is a priority.

Third, the research shows wide variety in the lifetimes and committed emissions profiles of different classes of ships, implying that targeted policies are needed. Refrigerated cargo ships have an average of 9 years likely future life, whereas for passenger ships it is 29 years. For ships and ship types with shorter remaining life, it’s hard for ship-owners to make a strong economic case for actions on their own, so the successful uptake of emission reduction measures requires action from policy makers, such as regulating on speed, setting standards on retro-fitting to improve efficiency, or market-based mechanisms that impact on fuel price.

Efficiency improvements on new ships won’t be enough

The committed emissions from ships are significant, yet a combination of policies on very low-carbon ships from 2030, combined with speed and operational measures from the early 2020s, could keep shipping within a Paris-compatible carbon budget. However, any delay to appropriate policy implementation would mean additional measures, including demand-side or early scrappage interventions, are needed to meet the Paris climate goals.

The time left to deliver on what is dictated by the global Paris Agreement is too short to rely on measures that predominantly focus on improving the efficiency of new ships. Policy makers should include a focus on measures that clearly target the existing fleet.