This briefing paper outlines a methodology for calculating well-to-wake CO2-equivalent emissions from four fossil marine fuels: heavy fuel oil, very low sulfur fuel oil, marine gas oil, and liquefied natural gas. Well-to-wake emissions, or life-cycle emissions, are the sum of upstream (well-to-tank) and downstream (tank-to-wake) emissions.

The number of ships using exhaust gas cleaning systems, better known as “scrubbers,” has grown from just three ships in 2008 to more than 4,300 in 2020.