An atmospheric scientist at NASA’s Goddard Space Flight Center, Led by Tianle Yuan discovered that the 2020 global sulfur cap had more successfully decreased decay than the provincial sulfur caps that forewent it.
The examination analyzed ship tracks; highly-concentrated clouds formed around the pollution emitted in ships’ exhausts that can be seen crisscrossing areas of ship operation.
Infrared imaging technology can differentiate ship tracks from marine clouds formed naturally around particles like sea salt due to the difference in their concentration and light-scattering properties.
With record low levels continuing into the most recently analyzed data in 2021, Yuan and colleagues concluded that the global Sulphur cap was responsible for the drop in ship tracks.
“Annual mean ship-track density decreases by 50% or more in five major shipping lanes compared to the climatological mean. The decline is even steeper if compared to 2019,” said the report.
IMO 2020 came into force on January 1, 2020, and limited the sulfur content of fuel oil to 0.5%, down from 3.5% before the regulation. The researchers said regional law on fuel sulfur content had proven less effective as ships altered course to avoid the affected areas.
The density of ship tracks also reflected economic trends in changes to the shipping industry.
“Trans-Pacific ship track patterns between Asia and the Americas reflect dips and spikes in trade. As outlined in the study, a general upward trend in shipping activity between 2003 and 2013—reflected in ship-track clouds—reversed for about a year in the aftermath of the 2008 global financial crisis. An even sharper decrease between 2014 and 2016 likely reflected a slowdown in Chinese imports and exports of raw materials and commodities,” said a NASA article on the study.
The complete study Global reduction in ship-tracks from sulfur regulations for shipping fuel is available online.