NASA: Limiting sulphur has reduced shipping air pollution

A new study by America’s iconic space agency has revealed measures introduced in 2020 significantly impacted emissions.

Rules put in place to limit the amount of sulphur in ship fuel have proven effective in reducing so-called ‘track clouds’, according to research based on satellite imagery. 

NASA studied the visible emission trails left by ships as they circumnavigate the globe, which are effectively long streams of air pollution, and found that across the planet’s busiest routes there were significantly less of these tell-tale signs of ocean-faring than the previous year.

While some of this does come down to pandemic-related circumstances, with notably less traffic on waters, particularly in terms of cruise ships and passenger ferries, this does not account for the extent of the reduction. As such it is believed the regulations on sulphur in fuel, introduced around the same time, has been responsible for a marked decline in track clouds.  

‘Without this kind of complete and large-scale sampling of ship tracks, we cannot begin to completely understand this problem,’ said lead author Tianle Yuan, an atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the University of Maryland, Baltimore County.

Overall, since the International Maritime Organisation introduced the new limits, sulphur content in ship fuel has plummeted by 86%, with no more than 0.5% of fuel allowed to comprise the heavily polluting element. In comparison, ship traffic only fell by around 1.4% for a few months as a result of the Covid-19 pandemic – not enough to explain the overall decline. 

Earlier this year, the world’s second largest shipping company, Maersk, announced that it was investing in off-shore, renewable electricity-powered buoys so ships waiting to dock do not need to continue running engines, and burning fuel.

Image: NASA