Section 1. As used in this chapter the following words shall have the following meanings unless the context clearly requires otherwise:—

''Adaptation'', adjustments in natural or human systems in response to actual or expected climatic stimuli and associated impacts, including but not limited to changes in processes, practices and protocols to increase resiliency of built and natural structures, moderate potential damages or benefit from opportunities associated with climate change.

''Allowance'', an authorization to emit, during a specified year, up to 1 ton of carbon dioxide equivalent.

''Alternative compliance mechanism'', an action undertaken by a greenhouse gas emission source that achieves the equivalent reduction of greenhouse gas emissions over the same time period as a direct emissions reduction, that is approved by the department, and that is real, permanent, quantifiable, verifiable and enforceable.

''Carbon dioxide equivalent'', the amount of carbon dioxide by weight that would produce the same global warming impact as a given weight of another greenhouse gas, based on the best available science, including from the Intergovernmental Panel on Climate Change.

''Department'', the department of environmental protection.

''Direct emissions'', emissions from sources that are owned or operated, in whole or in part, by an entity or facility including, but not limited to, emissions from factory stacks, manufacturing processes and vents, and company owned or company-leased motor vehicles.

''Direct emissions reduction'', a greenhouse gas emission reduction action made by a greenhouse gas emissions source at that source.

''Emission'', emission of a greenhouse gas into the air.

''Emissions reduction measures'', programs, measures, standards, and alternative compliance mechanisms authorized pursuant to this chapter, applicable to sources or categories of sources that are designed to reduce emissions of greenhouse gases.

''Entity'', a person that owns or operates, in whole or in part, a source of greenhouse gas emissions from a generator of electricity or a commercial or industrial site including, but not limited to, a transportation fleet.

''Executive office'', the executive office of energy and environmental affairs.

''Facility'', a building, structure or installation located on contiguous or adjacent properties of an entity.

''Greenhouse gas'', any chemical or physical substance that is emitted into the air and that the department may reasonably anticipate will cause or contribute to climate change including, but not limited to, carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride.

''Greenhouse gas emissions limit'', an authorization, during a specified year, to emit up to a level of greenhouse gases specified by the secretary, expressed in tons of carbon dioxide equivalents.

''Greenhouse gas emissions source'', a source, or category of sources, of greenhouse gas emissions with emissions that are at a level of significance, as determined by the secretary, that its participation in the program established under this chapter will enable the secretary to effectively reduce greenhouse gas emissions and monitor compliance with the statewide greenhouse gas emissions limit.

''Hazard mitigation'', any action that reduces or eliminates long-term risks caused by natural or man-made disasters.

''Indirect emissions'', emissions associated with the consumption of purchased electricity, steam and heating or cooling by an entity or facility.

''Leakage'', the offset of a reduction in emissions of greenhouse gases within the commonwealth by an increase in emissions of greenhouse gases outside the commonwealth.

''Market-based compliance mechanism'', (i) a system of market-based declining annual aggregate emissions limitations for sources or categories of sources that emit greenhouse gases; or (ii) greenhouse gas emissions exchanges, banking, credits and other transactions governed by rules and protocols established by the secretary or the regional greenhouse gas initiative, that result in the same greenhouse gas emissions reduction, over the same time period, as direct compliance with a greenhouse gas emissions limit or emission reduction measure adopted by the executive office pursuant to this chapter.

''Nature-based solutions'', strategies that conserve, create, restore and employ natural resources to enhance climate adaptation, resilience and mitigation to mimic natural processes or work in tandem with man-made engineering approaches to address natural hazards like flooding, erosion, drought and heat islands and to maintain healthy natural cycles to sequester and maintain carbon and other greenhouse gases.

''Person'', an agency or political subdivision of the commonwealth, a state, public or private corporation or authority or an individual, trust firm, joint stock company, partnership, association or other entity or group thereof or an officer, employee or agent thereof.

''Secretary'', the secretary of energy and environmental affairs.

''State plan'', the integrated state climate adaptation and hazard mitigation plan which shall include the state hazard mitigation plan, required by the Robert T. Stafford Disaster Relief and Emergency Assistance Act, Public Law 93–288, 42 U.S.C. section 5121, et seq., and any subsequent revisions of the plan developed pursuant to this chapter.

''Statewide greenhouse gas emissions'', the total annual emissions of greenhouse gases in the commonwealth, including all emissions of greenhouse gases from the generation of electricity delivered to and consumed in the commonwealth, accounting for transmission and distribution line losses, whether the electricity is generated in the commonwealth or imported; provided, however, that statewide greenhouse gas emissions shall be expressed in tons of carbon dioxide equivalents.

''Statewide greenhouse gas emissions limit'', the maximum allowable level of statewide greenhouse gas emissions in a given year, as determined by the secretary.

''Vulnerability assessment'', an evaluation of degree of susceptibility to, or ability to cope with, adverse effects of climate change, such as climate variability and extremes, including an evaluation of adaptive capacity and subsequent adaptation strategies and options for the asset, system, institution or other subject being assessed.