1. Short title This Act may be cited as the Clean Shipping Act of 2023 . 2. Marine Zero Greenhouse Gas Fuel Standard The Clean Air Act is amended by inserting after section 212 ( 42 U.S.C. 7546 ) the following: 212A. Marine Zero Greenhouse Gas Fuel Standard (a) Marine vessel fuel carbon intensity standards (1) Standards The Administrator shall, by regulation and except as provided in paragraph (3), require each vessel on a covered voyage to comply with standards for the carbon intensity of the fuel used by that vessel so that the carbon intensity is— (A) in each of calendar years 2027 through 2029, at least 20 percent less than the carbon intensity baseline; (B) in each of calendar years 2030 through 2034, at least 45 percent less than the carbon intensity baseline; (C) in each of calendar years 2035 through 2039, at least 80 percent less than the carbon intensity baseline; and (D) in calendar year 2040 and each calendar year thereafter, 100 percent less than the carbon intensity baseline. (2) Promulgation of standards The Administrator shall finalize— (A) the standard required by paragraph (1)(A) by not later than January 1, 2026