Ship air emissions may be grouped, subject to their general impact, to emissions causing air pollution, the so-called air pollutants, and emissions contributing to climate change, the so-called greenhouse gases (GHG).
Sulphur oxides (SOx), nitrogen oxides (NOx), particulate matter (PM), carbon monoxide (CO), volatile organic compounds (VOC) and ozone (O3), are the most important air pollutants, whereas carbon dioxide (CO2), and methane (CH4) are the main greenhouse gases of shipping. Air pollution and climate change can be also intertwined since some of the air pollutants have also a climate forcing potential. Tropospheric ozone and black carbon (BC), a constituent of PM, are examples of air pollutants contributing also to global warming. Other PM components, such as sulphates and nitrates, listed as important air pollutants with negative impacts on human health, may have a positive (cooling) effect to climate change (IPCC, 2013).
Air pollution and GHG from all anthropogenic activities create certain forms of external cost (i.e. the cost from an economic activity that is transferred to third parties without being counted in the overall cost of this activity). A typical example of external cost is the additional cost payed by an individual for medical and/or health insurance services in an effort to avoid the consequences of being exposed to polluted air. This exposure to polluted air is an every-day reality for nine out of ten people according to the World Health Organisation, which presently, considers air pollution as the greatest environmental risk to human health (WHO, 2O19).
Assessing the total impact from ship air emissions is a very challenging task. For air pollutants, impact estimates can be rather complex since except for the quantity of the emission, additional parameters should be also taken into account, such as the properties of the emitted substance, the environmental conditions, and info on the receiving environment and the exposed population. Assessing the impact of GHG is even more complex. The Intergovernmental Panel on Climate Change (IPCC) emphasizes that estimates of the social costs of climate change have a wide range of uncertainty because of the limited knowledge of impacts, uncertain future of technological and socio-economic developments, and the possibility of other unforeseen events (IPPC, 2017).
For the maritime transport sector, the general social protection strategy (e.g. in EU) requires addressing the external cost of ship air emissions by implementing measures which internalise this cost into the transport process. The regulator has the following two different options to achieve this: a. command-and-control regulations: setting emissions limits; and b. market based measures: pricing methods with taxes on emissions, or cap-and-trade solutions that permit the exchange of air emissions rights.
The environmental agenda of shipping keeps growing in recent years with regulations covering air pollution (e.g. the sulphur content limits in marine fuels) and GHG in ship design and ship operation. Especially for GHG, regulators often have different approaches on when and how to enforce new rules which adds additional (and unnecessary) pressure to shipping. The case of the EU Monitoring Reporting and Verification (MRV), and the IMO Data Collection Scheme (DCS), is illustrative in this respect.
International shipping emits less than 1000 million tonnes of CO2 annually, and is responsible for about 2.6% of global GHG (ICCT, 2017). Yet, GHG from shipping are expected to increase between 50% and 250% by 2050 – depending on future economic and energy developments. This is not compatible with the so-called Paris Agreement adopted in 2015, which has set the specific goal of holding global warming to well below 2 degrees Celsius, compared to pre-industrial levels, and of pursuing efforts to limit it to 1.5°C (UNEP, 2017). To meet these targets, the shipping sector will have to cut in half the worldwide GHG by 2050. This target is included in the recent IMO’s Initial Strategy on the reduction of GHG emissions, as agreed in MEPC 72. The strategy contains a list of activities with relevant timelines and candidate short-, mid-, and long-term measures. In the short-term period (2018 – 2023), shipping will have to boost energy efficiency in the context of the EEDI and the SEEMP, and in addition to evaluate new measures (e.g. speed reduction), never considered before. In the mid-term period (2023 – 2030), a notable potential entry is the IMO market-based mechanism, which however remains to be seen if it will be in line with the emission-trading scheme proposed by EU. In the long-term period (2030 and onwards), the main goal will be to develop zero-carbon or fossil-free fuels in order to de-carbonise shipping in the second half of the century.
The new strategy of IMO reflects the willingness of international shipping to contribute to the sustainable development goals set by the United Nations in 2015. Shipping is undoubtedly contributing to sustainability by providing accessibility to goods, services, and activities, carrying more than 80% of the global trade by volume (UNCTAD 2018). The IMO strategy, puts focus on the two remaining principles of sustainability (i.e. acceptance of resource constrains and equality), by enforcing new measures and technologies to eliminate the impact of shipping to human health and the environment. This corresponds to one big, but also worth taking challenge for the industry in the upcoming years.
* Senior Manager, Global Marine Training RINA Hellas Ltd.