1. No later than one year after the effective date of this article, the department shall, pursuant to rules and regulations promulgated after at least one public hearing, establish a statewide greenhouse gas emissions limit as a percentage of 1990 emissions, as estimated pursuant to section 75-0105 of this article, as follows:

a. 2030: 60% of 1990 emissions.

b. 2050: 15% of 1990 emissions.

2. Greenhouse gas emission limits shall be measured in units of carbon dioxide equivalents and identified for each individual type of greenhouse gas.

3. In order to ensure the most accurate determination feasible, the department shall utilize the best available scientific, technological, and economic information on greenhouse gas emissions and consult with the council, stakeholders, and the public in order to ensure that all emissions are accurately reflected in its determination of 1990 emissions levels.

4. In order to comply with the statewide greenhouse gas emissions limits promulgated pursuant to this section, a source may utilize the alternative compliance mechanism established pursuant to subdivision four of section 75-0109 of this article. The use of such mechanism shall be in accordance with the provisions of that subdivision.