By Marilis Azzopardi

It is estimated that in Europe alone, around 50,000 people die prematurely due to air pollution from shipping. 90% of the world trade relies on shipping, and most of the larger vessels use cheaper bunker fuel oil to keep costs down. Ships burn fuel that is 3500 times dirtier than road diesel, yet most have no exhaust abatement technology installed. Bunker fuel is the liquid fuel oil that is left after the fractionated distillation of crude oil. This results in a sticky viscous liquid concentrating many toxic compounds which then get released into the air when it burns or into the marine environment from oil spills. The industry material hazard sheets define fuel oil as highly toxic to aquatic organisms; it does not evaporate easily and takes a long time to biodegrade.

When fuel is burned to provide energy, pollutants such as nitrogen oxides (NOx), sulphur dioxide (SO2), heavy metals and fine particulate matter are generated and/or released into the surrounding air. One large ship can generate about 5000 tonnes of sulphur oxides in the 280 days that it operates a year. Contrast that with the 101g of sulphur oxides produced annually by a car driven for around 15,000km. These not only have an impact on air quality; the NOx and SO2 combine with the gases in air to form acids which in turn react with more air to form sulphates and nitrates which ultimately cause acid rain and are deposited in soils and contribute to eutrophication. The bunker fuel exhaust also contains heavy metals and polycyclic aromatic hydrocarbons which are toxic, mutagenic and/or carcinogenic. Nickel is one such heavy metal which has often breached EU annual limits in Gibraltar.

Ships burn fuel that is 3500 times dirtier than road diesel, yet most have no exhaust it does not evaporate easily and takes a long time to biodegrade.

By January 1st 2020, the International Maritime Organisation will require the global shipping fleet to switch to fuels containing a maximum of 0.5% sulphur. This reduction from the current limit of 3.5% is expected to prevent an estimated 150,000 deaths and 7.6 million cases of childhood asthma cases each year. The sulphur caps that have already been established in emission control areas in North America, the Baltic Sea and certain areas in China have led to improvements in air quality. In the EU, ships will be allowed to use emission abatement methods such as scrubbers as an alternative to switching to the more expensive low-sulphur fuels.

Shipping is also a major contributor of black carbon emissions, which are estimated to cause around 3 million premature deaths annually (IGSD/INEE, 2008). Black carbon is one of the main components of the soot particles generated by the incomplete combustion of fuels, especially bunker fuel oils, and one of the largest contributors to global warming, second only to carbon dioxide. One study by NOAA and the University of Colorado found that tug boats are one of the worst offenders, emitting more soot for the amount of fuel burnt when compared with other vessels. When emitted into the air, the sooty particles absorb sunlight, creating a haze that interferes with cloud and rain formation, darkens snow and ice surfaces and contributes to melting of snow in the polar regions (Ramanathan and Carmichael, 2008).

Black carbon plays a significant role in global warming, but the effects last for weeks as opposed to years with carbon dioxide. This makes it an ideal target in a strategy that aims to tackle the problem of global warming in the short term, and something that will have an effect right now.

According to the International Council on Clean Transportation, the largest producers of CO2 emissions are the larger vessels such as container ships, followed by bulk carriers and oil tankers. Data from the International Maritime Organisation show that international shipping comprises around 2.2% of all global greenhouse gas emissions and 2.1% of carbon dioxide emissions. In a 2016 inventory of ship traffic exhaust emissions (Jalkanen et al, 2016), Gibraltar harbour ranked second amongst the European areas with the highest CO2 emissions. Despite Gibraltar’s small size, we have a pretty large carbon footprint.