SECTION 1. (a) Section 1 of chapter 21N of the General Laws, as appearing in the 2014 Official Edition, is hereby amended by inserting, in line 60, after the word “chapter” the following words:- ; or (iii) an economy-wide price on carbon

(b) Said section 1 of said chapter 21N, as so appearing, is hereby amended by striking out, in line 54, the word:-  “or”

(c) Subsection (b) of said section 7 of said chapter 21N of the General Laws, as so appearing, is hereby amended by striking out, in line 15, the word “may” and inserting in place thereof the following word:- shall

(d) Said subjection (b) of said section 7 of said chapter 21N of the General Laws, as so appearing, is hereby amended by inserting, in line 16, after the word “mechanisms” the following words:- , including, but not limited to, an economy-wide price on carbon,

(e) Said subsection (b) of said section 7 of said chapter 21N of the General Laws, as so appearing, is hereby amended by inserting after the last sentence the following words:- All revenue derived from said economy-wide price on carbon shall be returned to all Massachusetts residents through a revenue rebate program established by the Department of Revenue.

SECTION 2. Section 1 shall take effect on January 1, 2020 if the Commonwealth fails to meet the 2020 statewide greenhouse gas emissions limit set pursuant to subsection (b) of section 3 of chapter 21N of the General Laws and adopted pursuant to subsection (a) of section 4 of said chapter by January 1, 2020.