Interpretation U.K. 92 Meaning of "greenhouse gas" U.K. (1) In this Act " greenhouse gas " means any of the following- (a) carbon dioxide (CO 2 ), (b) methane (CH 4 ), (c) nitrous oxide (N 2 O), (d) hydrofluorocarbons (HFCs), (e) perfluorocarbons (PFCs), (f) sulphur hexafluoride (SF 6 ), [ F1 (g) nitrogen trifluoride (NF 3 ). ] (2) The Secretary of State may by order amend the definition of "greenhouse gas" in subsection (1) to add to the gases listed in that definition. (3) That power may only be exercised if it appears to the Secretary of State that an agreement or arrangement at European or international level recognises that the gas to be added contributes to climate change. (4) An order under this section is subject to negative resolution procedure. 92(1)(g) inserted (3.2.2023) by The Climate Change (Targeted Greenhouse Gases) Order 2023 (S.I. 2023/118) , arts. 1(2) , 3(3) 93 Measurement of emissions etc by reference to carbon dioxide equivalent U.K. (1) For the purposes of this Act greenhouse gas emissions, reductions of such emissions and removals of greenhouse gas from the atmosphere shall be measured or calculated in tonnes of carbon dioxide equivalent. (2) A " tonne of carbon dioxide equivalent " means one metric tonne of carbon dioxide or an amount of any other greenhouse gas with an equivalent global warming potential (calculated consistently with international carbon reporting practice). 94 Meaning of "international carbon reporting practice" U.K. (1) In this Act " international carbon reporting practice " means (c. 30), (b) an enactment contained in, or in an instrument made under, an Act of the Scottish Parliament, (c) an enactment contained in, or in an instrument made under, Northern Ireland legislation, and (d) an enactment contained in, or in an instrument made under, a Measure or Act of the National Assembly for Wales; " European law " means- (a) all the rights, powers, liabilities, obligations and restrictions from time to time created or arising by or under the [ F2 EU ] Treaties, and (b) all the remedies and procedures from time to time provided for by or under the [ F2 EU ] Treaties, and "European policy" has a corresponding meaning; " modifications ", in relation to an enactment, includes additions or amendments to, or omissions from, the enactment; " primary legislation " means- (a) an Act of Parliament, (b) an Act of the Scottish Parliament, (c) a Measure or Act of the National Assembly for Wales, or (d) Northern Ireland legislation. 2011 (S.I. 2011/1043), arts. 2, 3, 6 (with art. 3(2)(3)4(2)6(4)6(5)) 98 Index of defined expressions U.K. In this Act the following expressions are defined or otherwise explained by the provisions indicated- "the 1990 baseline" (in Parts 1 and 2) section 1(2) "administrator" (in Part 3) section 55 "administrator" (in Schedule 6) paragraph 6(1) and (4) of Schedule 6 "affirmative resolution procedure" (except in Part 3 and Schedule 6) section 91(1) " annual equivalent ", in relation to the carbon budget for a period (in Parts 1 and 2) section 5(2) "budgetary periods" (in Parts 1 and 2) section 4(1) "carbon budget" (in Parts 1 and 2) section 4(1) "carbon unit" (in Parts 1 and 2) section 26(1) "the chair" (in Schedule 1) paragraph 1(1) of Schedule 1 [ F3 "children" (in Schedule 6) ] [ F3 paragraph 4B(2) of Schedule 6 ] "civil sanction" (in Schedule 6) paragraph 9(3) of Schedule 6 "the Committee" (in Part 2) section 32 "Counsel General" (in sections 61 to 70) section 70(8) "the deputy chair" (in Schedule 1) paragraph 2 of Schedule 1 "devolved authority" (in sections 61 to 70) section 70(3) " devolved functions ", in relation to a reporting authority (in sections 61 to 69) section 70(4) and (5) "devolved legislature" section 97 " devolved Welsh functions ", in relation to a reporting authority (in sections 61 to 69) section 70(6) and (7) "discretionary requirement" (in Schedule 6) paragraph 12(3) of Schedule 6 "electricity distributor" (in Schedule 4) paragraph 2(3) of "electricity supplier" (in Schedule 4) paragraph 2(2) of "emissions" section 97 "enactment" section 97 "environmental authority" (in Schedule 4) paragraph 1(2) of European law" section 97 "European policy" section 97 "financial year" (in Schedule 1) paragraph 23 of Schedule 1 "fixed monetary penalty" (in Schedule 6) paragraph 10(3) of Schedule 6 "greenhouse gas" section 92 "international carbon reporting practice" section 94 "Minister of the Crown" (in sections 61 to 70) section 70(8) " modifications ", in relation to an enactment section 97 "national authority" section 95 "negative resolution procedure" (except in Part 3 and Schedule 6) section 91(2) "net UK carbon account" (in Parts 1 and 2) section 27(1) "net UK emissions" for a period, in relation to a greenhouse gas (in Parts 1 and 2) section 29(1) "non-monetary discretionary requirement" (in Schedule 6) paragraph 12(4) of Schedule 6 [ F4 "nuisance" (in Schedule 6) ] [ F4 paragraph 4B(6) of Schedule 6 ] "participant" (in Part 3) section 55 [ F5 "pollution" (in Schedule 6) ] [ F5 paragraph 4B(3) of Schedule 6 ] "potential participant" (in Schedule 4) paragraph 3(2) of "primary legislation" section 97 "the relevant national authority" (in Part 3) section 47 "the relevant national authority" (in Schedule 6) section 77(3) "the relevant Northern Ireland department" section 96 "reporting authority" (in sections 61 to 70) section 70(1) and (2) "seller" (in Schedule 6) paragraph 3 of Schedule 6 " [ F6 single use carrier bag ] [ F6 carrier bag ] " (in Schedule 6) paragraph 5 of Schedule 6 "specified" (in Schedule 6) paragraph 3(4) of Schedule 6 "targeted greenhouse gas" (in Parts 1 and 2) section 24(1) "trading period" (in Part 3) section 55 "trading scheme" section 44(2) " UK emissions ", in relation to a greenhouse gas (in Part 1) section 29(1) " UK removals ", in relation to a greenhouse gas (in Part 1) section 29(1) "variable monetary penalty" (in Schedule 6) paragraph 12(4) of Schedule 6 "Wales" (in sections 61 to 70) section 70(8) F7 ... F7 ... [ F8 "young people" (in Schedule 6) ] [ F8 paragraph 4B(8) of Schedule 6 ] 98 Table inserted (E.W.) (15.2.2011) by (Wales) Measure 2010 (nawm 8) , s. 21(2) , Sch. para. 2(2) F4 Words in s. 98 Table inserted (E.W.) (15.2.2011) by (Wales) Measure 2010 (nawm 8) , s. 21(2) , Sch. para. 2(3) F5 Words in s. 98 Table inserted (E.W.) (15.2.2011) by (Wales) Measure 2010 (nawm 8) , s. 21(2) , Sch. para. 2(4) F6 Words in Act substituted (N.I.) (28.4.2014) by (Northern Ireland) 2014 (c. 7) , s. 1(a) F7 S. 98 entry repealed (15.1.2012) by Localism Act 2011 (c. 20) , s. 240(1)(m) , Sch. 25 Pt. 8 F8 Words in s. 98 Table inserted (E.W.) (15.2.2011) by (Wales) Measure 2010 (nawm 8) , s. 21(2) , Sch. para. 2(5)