CII

The Carbon Intensity Indicator is the annual operational rating of ships of 5,000 GT and above under MARPOL Annex VI Reg.28, in force from 1 January 2023. A ship’s attained CII (usually the AER, grams CO2 per deadweight-tonne-mile) is compared against a required value to assign a band from A to E. The required value tightens each year through a reduction factor: the schedule runs at 13.625, 16.25, 18.875, and 21.5 percent below the 2019 reference line for 2027 through 2030 under MEPC.400(83). A D rating for three consecutive years, or a single E, triggers a corrective action plan in the SEEMP.