(1)    The Secretary of State may by order—

(a)    amend the percentage specified in section 1(1);

(b)    amend section 1 to provide for a different year to be the baseline year.

(2)    The power in subsection (1)(a) may only be exercised—

(a)    if it appears to the Secretary of State that there have been significant developments in—

(i)    scientific knowledge about climate change, or

(ii)    European or international law or policy,

that make it appropriate to do so, or

(b)    in connection with the making of—

(i)    an order under section 24 (designation of further greenhouse gases as targeted greenhouse gases), or

(ii)    regulations under section 30 (emissions from international aviation or international shipping).

(3)    The developments in scientific knowledge referred to in subsection (2) are—

(a)    in relation to the first exercise of the power in subsection (1)(a), developments since the passing of this Act;

(b)    in relation to a subsequent exercise of that power, developments since the evidential basis for the previous exercise was established.

(4)    The power in subsection (1)(b) may only be exercised if it appears to the Secretary of State that there have been significant developments in European or international law or policy that make it appropriate to do so.

(5)    An order under subsection (1)(b) may make consequential amendments of other references in this Act to the baseline year.

(6)    An order under this section is subject to affirmative resolution procedure.