Air pollution-busting ship fuel in climate backlash

(EurActiv, 20 Jan 2020) New rules aimed at reducing air pollution from shipping may worsen the sector’s climate impact, according to new research, which warns that low sulphur fuels could end up producing more climate-bashing emissions, known as black carbon.

On 1 January, International Maritime Organisation (IMO) rules came into force, lowering the legal sulphur limit of boat fuel from 3.5% to just 0.5%, in a bid to improve air quality and reduce the causes of acid rain.

But new figures submitted to the IMO by Finland and Germany, ahead of an annual meeting of its pollution prevention committee meeting in February, warn that the tweaked fuels have the potential to do serious climate harm.

That is because the very-low sulphur fuel oils (VLSFO) tested contained more hydrocarbons known as aromatics, which in turn cause more black carbon emissions (BC). BC is perhaps second only to CO2 in terms of climate-damaging potential.  

According to the study, the hybrid fuels tested contained between 70% and 95% more aromatic compounds, which led to 10% to 85% more BC compared to standard heavy fuel oil (HFO), a widely used shipping fuel.

Due to their strong black colour, BC emissions absorb sunlight to a greater degree and therefore have an increased warming effect. In the polar regions, they are particularly problematic as they stick to snow and increase melt rates.

A silver lining of BC emissions is that they remain in the atmosphere for less time than CO2 and dissipate within weeks. Aside from shipping, they are also regularly produced by wood-burning stoves and forest fires.

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EurActiv, 20 Jan 2020: Air pollution-busting ship fuel in climate backlash