Today, emissions from maritime transport account for 10% to 15% of global, human-related sulphur-oxide (SOx) and nitrogen-oxide (NOx) emissions, and about 3% of global carbon-dioxide (CO2) emissions. Current maritime emission regulations set limits for SOx and NOx specifically for health and environmental reasons, and for CO2 in order to mitigate global warming.

The International Maritime Organization (IMO) is currently working on extending locally and regionally motivated emissions regulations — the emission control areas (ECAs) in North America and Northern Europe — to a globalised (0.5%