The long-awaited deadline for the International Maritime Organization (IMO) global sulfur cap arrived on Jan. 1, 2020. The sulfur cap reduces the amount of sulfur in fuels from 3.5% m/m (mass by mass) to 0.5% m/m. The drastic reduction is in line with IMO goals for emissions reductions by 2050 and is expected to cost the shipping industry — and its sprawling supply chain — billions of U.S. dollars in compliance costs.

The announcement of a new sulfur cap in 2016 came after decades of study and several additions made to Annex VI of the International Convention for the Prevention of Pollution from Ships (MARPOL),^[1] which went into force in 2005. Annex VI calls for IMO member states to create regulations to reduce polluting airborne emissions from ships, including sulfur oxides, nitrogen oxides, ozone-depleting substances and volatile organic compounds. The dramatic reduction in sulfur is part of an ongoing tightening of emissions rules beginning with Annex VI.