Black carbon in shipping and aviation: A G20 imperative on trade and climate emissions

10 October 2017

Black carbon is a particulate matter with major implications on climate change, public health, and food production. In this post, the author puts forward a set of six policy recommendations arguing that there are numerous opportunities for the G20 to make significant contributions to efforts to address the black carbon challenges.


This summer’s G20 summit was a watershed event in the history of international governance: the G20 became the “G19” on climate change issues and the “G18” on international trade issues. The former, of course, was a result of the US having previously announced its intention to withdraw from the Paris Climate Agreement and then not agreeing to a strong G20 statement on climate action at the Hamburg summit. The latter was a result of the UK’s Brexit from the EU and the US government’s attacks on free trade and international trade agreements.

The new context

These G20 developments were part of a larger political-ideological shift in the international institutional landscape – a shift away from institutionalised international cooperation on trade and on climate issues respectively, to an emphasis on obstructionism by one of its largest members, namely the US national government.

By coincidence, in addition to this political-ideological shift, there is also a historically significant industrial-technological shift in progress – a shift from internal combustion engines to electric power. This shift is also part of larger issues concerning black carbon (BC) emissions in maritime shipping and in aviation as well as motor vehicles.

The coincidental combination of the political-ideological shift and the industrial-technological shift presents a fundamentally different set of issues for both the international trade and climate agendas of the G20 and many other institutional venues.

Black carbon problems

In order to understand the nature and implications of these shifts, it is necessary to be familiar with key features of BC:

  • Climate change: BC is second after carbon dioxide in its global warming impact;
  • Public health: BC causes millions of deaths per year; and
  • Food production: BC deposits destroy millions of tonnes of food crops per year.

Black carbon is a major component of “soot,” including in transportation sector emissions. Unless there are significant changes in policies at many levels of governance, total global BC emissions are expected to rise for decades. Although BC transportation emissions are reported to be decreasing in some countries, they are increasing in most of the world, and transportation is still the dominant sectoral source of BC in “developed” countries.

Diesel engines contribute most of transportation’s BC emissions. Maritime shipping’s BC emissions have been forecast to triple by 2050 versus 2004, despite fuel efficiency regulations by the International Maritime Organization (IMO). As for aviation, although aviation fuel is not diesel, it nevertheless produces BC emissions which are especially intense and locally deposited during take-off and landing. The combination of an expected doubling or more of air traffic volume – together with more extensive and more accurate estimates of aviation’s BC emissions – will yield significantly greater forecasts of BC emissions in business-as-usual scenarios of aviation’s contributions to global warming.

BC emissions can be mitigated by cost-effective technologies that are readily available – and others that are in active R&D stages. In particular, diesel particulate filters (DPFs) have been widely used for motor vehicles for many years, and they have also been in use on small marine shipping vessels. Their potential for adaptation is practical and cost-effective for many types and sizes of vessels. There is also increasing interest in electric propulsion for vessels, as an alternative to diesel. In the aviation sector, there are many opportunities for improved fuel efficiency, in both aircraft design and operations.

Black carbon on the international agenda

Because BC is particulate matter – not a gas – it has not been actively addressed in the multilateral UNFCCC climate regime. Black carbon has likewise not received formal attention at the International Civil Aviation Organization (ICAO) and is not included in the preliminary design of its Carbon Offset and Reduction Scheme, despite BC’s presence in aviation emissions.

It is however acknowledged in the IMO, where BC has been officially defined on the basis of independent academic research, and there is IMO technical work in progress on the development of a BC measurement protocol. It is also a central concern of the Climate and Clean Air Coalition (CCAC) at UNEP, where there are BC programmes in progress – for instance, Reducing Emissions from Ports and Marine Vessels and a Heavy-Duty Diesel Vehicles and Engines Initiative. Furthermore, there has been much technical work on measuring and reporting BC emissions by the Arctic Council and the European Environment Agency, as well as the NGOs Transport & Environment, International Council on Clean Transportation and French government labs.

Black carbon on local agendas

The climate change – and health – consequences of BC emissions are now salient in local air quality policies in many large cities. Athens, Madrid, Mexico City and Paris plan to bandiesel cars; Barcelona, Berlin, Cologne, Munich and Stuttgart are putting in place other kinds of restrictions on diesel vehicles or considering them. In North America, Los Angeles, Long Beach, Oakland and Vancouver have adopted policies that reduce BC emissions in their seaports.

In Asia, among the most important policy issues are those concerning the major long-term seaport expansion plans of India and China. India has plans to develop ten new mega-ports and upgrade twelve existing government-owned ports. A central question for these Indian and Chinese ports is whether they will adopt policies that limit BC emissions.

In aviation, a current specific issue is whether there will be restrictions, including perhaps prohibitions of airport expansions. London’s Heathrow airport is the best known – and as yet unresolved – case;  but airport expansion plans in other countries are also in doubt, for instance in Austria, France, Germany and Ireland.

The G20 and black carbon

Since G20 countries account for about three-fourths of international trade, they have a major stake in trade-related BC emissions, and they have an opportunity as well as a responsibility to control the BC emissions of shipping and aviation. Such emissions are especially problematic in cities with seaports and airports, and many of the busiest among them are of course in G20 countries.

Action on transport-related emissions from this group could therefore make a meaningful contribution to reducing international transport emissions and send strong signals to the international community to scale up efforts. The following set of recommendations should be considered.

  • Eight governments of the G20 are not “country partners” of the Climate and Clean Air Coalition – namely Argentina, Brazil, China, India, Indonesia, Saudi Arabia, South Africa, and Turkey. They should all join the CCAC before the next G20 summit, and any that do not should be explicitly noted at the G20 meeting as being a non-participant.
  • Eighteen of the world’s top 20 seaports by total volume and all the world’s top 20 airports in terms of take-offs and landings are located in G20 countries. Black carbon emissions are thus a widespread local health problem in G20 economies as well as a global climate change problem to which G20 countries are major contributors. All of the G20 governments should thus actively support local government programmes to reduce BC emissions in seaport and airport facilities.
  • The G20 could require the use of diesel particulate filters (DPFs) by vessels entering their seaports, and they could require DPFs on all ground equipment in seaports and airports.
  • The G20 should encourage and fund the expansion of international knowledge-sharing and best-practices programmesat the local level among their seaports and airports and develop international programmes to facilitate transfers of BC mitigation technologies.
  • The G20 should could actively promote more urgent actions in both ICAO and IMO for significant BC emissions reductions. They should call upon industries, including maritime shipping and aviation, to address BC issues more urgently.
  • The G20 could also address trade barriers related to BC mitigation goods and services in the Environmental Goods Agreement (EGA) negotiations and/or other trade negotiating venues.

In sum, there are numerous opportunities for the G20 – perhaps as the G19 – to make significant contributions to efforts to address the black carbon challenges.


Thomas L. Brewer is a Senior Fellow at the International Centre for Trade and Sustainable Development (ICTSD) and also Convener of the E15 Expert Group on Measures to Address Climate Change and the Trade System.

ICTSD gratefully acknowledges funding from the KR Foundation—Denmark for this project.