gas emissions are achieved to fully compensate for any amount by which greenhouse gas emissions from such fuels during the period referred to in subsection (e)(2) exceeded the levels at which such emissions would have been if subsection (a) had never applied. (2) Deadline for finalizing regulations The Administrator shall finalize any regulations required by paragraph (1) not later than two years after the Administrator makes the relevant determination pursuant to such paragraph. (3) Achievement of additional reductions Regulations issued pursuant to paragraph (1) shall ensure that any additional reductions required by paragraph (1)(B) are fully achieved by no later than eight years after the Administrator makes the determination described in subsection (e)(1). (g) Definitions In this section— (1) Greenhouse Gas The term greenhouse gas means carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), sulfur hexafluoride (SF6), hy­dro­fluo­ro­car­bons (HFCs), perfluorocarbon (PFCs), and other gases as defined by rule of the Administrator. (2) Greenhouse Gas Effect The term greenhouse gas effect means the adverse effects of greenhouse gases on health or welfare caused by the greenhouse gas’s heat-trapping potential or its effect on ocean acidification. . (b) New motor vehicles and new motor vehicle engines Section 202(b) of the Clean Air Act ( 42 U.S.C. 7521(b) ) is amended— (1) by redesignating the second paragraph (3) (as redesignated by section 230(4)(C) of Public Law 101–549 (104 Stat. 2529)) as paragraph (4)