GHG Emissions and Mitigation Policies

This page offers detailed insights into the Commonwealth's progress toward the goals of the Global Warming Solutions Act.

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The most recent Massachusetts Greenhouse Gas (GHG) Inventory shows that GHG emissions in 2017 were 22.4% below the 1990 baseline level, on track to meet the 25% reduction by 2020 required by the Global Warming Solutions Act (GWSA). Massachusetts' success in reducing GHG emission comes despite a 14% growth in population and 24% growth in vehicle miles traveled. Significant GHG emissions reduction from the electric sector since 2005 has been a major contributor to the drop in gross GHG emissions. Additionally, vehicle standards have lowered the carbon intensity of each vehicle mile traveled while the Commonwealth's nation-leading energy efficiency programs have helped to control energy demands in buildings despite economic growth and variable (and, at times, harsh) weather conditions. See more about the Commonwealth’s policies for mitigating GHG emissions.

Unlike many states and nations, emissions in Massachusetts do not primarily come from large industrial or agricultural operations. Over 65% of Massachusetts’ emissions come from our cars, trucks, homes, and offices; another 20% comes from the power plants that provide electricity for our lights, computers, and appliances.

Real Impacts, Coordinated Response

Climate change presents a serious threat to the Commonwealth’s residents, communities, environment, and economy. Sea-level rise threatens to eat away at Massachusetts’ populous coastline, while stronger and more frequent weather events pose dangers to public safety and the lives and property of our residents. The resilient MA Climate Clearinghouse provides communities with the best science and data on expected climate changes, information on community resiliency, and links to important grant programs and technical assistance.

In the last ten years, the Commonwealth has led the nation in reducing greenhouse gas emissions and has helped fuel a new economy built on innovation and technology.  As we look to 2020 and beyond, Massachusetts has an opportunity to continue its leadership, working with regional states and partners through programs like the Regional Greenhouse Gas Initiative, the Transportation and Climate Initiative, and the U.S. Climate Alliance. Global warming is a problem Massachusetts cannot solve alone. Only by engaging and working with our partners in New England and across the world will we be able to reduce greenhouse gas emissions, preserve our natural resources, continue to grow our economy, and protect our residents and communities from the impacts of climate change. Click here to read more about the Commonwealth’s plans and efforts to reduce GHG emissions, build resilience, and adapt to the impacts of climate change here in Massachusetts, across state lines, and across the world.

Greenhouse Gas Emissions Trends

Policies to reduce the use of carbon-intensive fuels, along with impacts from market forces, have dramatically reduced the amount of coal and petroleum consumed for electricity generation. Total petroleum use statewide, however, has only declined modestly as total gasoline consumption has risen since 1990. Many homes and businesses have switched over from petroleum to natural gas for space heating and other thermal needs. Massachusetts’ nation-leading efficiency programs have kept emissions in the buildings sector stable while population has grown 14% between 1990 and 2017.

Policy Implementation Overview

Since the passage of the GWSA in 2008, Massachusetts has created a strong framework of state laws, regulations, and executive orders that guides the Commonwealth’s actions to address climate change. The framework builds on the three overarching strategies through which the Commonwealth can effectively reduce GHG emissions: increased energy efficiency, end-use electrification, and electricity decarbonization. The Massachusetts Updated Clean Energy and Climate Plan for 2020 (CECP)  featured a broad suite of policies that aim to reduce GHG emissions in the Commonwealth across all sectors through increased energy efficiency in buildings and vehicles, the electrification of vehicles and thermal conditioning in buildings, and the replacement of carbon intensive fuels with renewable energy sources.

The following provides a brief overview of major policy initiatives. For a more detailed analysis of Massachusetts’ progress in implementing the CECP, please review the GWSA 10-Year Progress Report.

Electricity Generation

In 1990, power sector emissions were comparable to emissions from combustion of fuels in buildings and in vehicles, but they have since fallen by nearly 50%. This progress has been dominated, in quantitative terms, by the closure of coal- and oil-fired power plants, driven both by changes in relative fuel costs and by federal and state regulations.

Looking to the future, Massachusetts’ Renewable Energy Portfolio Standard (RPS) and Clean Energy Standard (CES) will continue to cut power sector emissions by requiring at least 80% of all electricity sold in the state to be clean or renewable by 2050. In addition, MassDEP's Electricity Generator Emissions Limits are working to gradually restrict the amount of carbon dioxide the Commonwealth's remaining fossil-fuel power plants are allowed to emit. Careful management of the electricity grid and procurement of energy resources, such as offshore wind and Canadian hydroelectric power, will ensure that electricity remains affordable and reliable, as well as safe and clean.

For a more detailed analysis of Massachusetts’ progress, please review the GWSA 10-Year Progress Report.


Transportation emissions are a product of the total miles driven (often referred to as vehicle-miles traveled, or VMT) and the fuel efficiency of those vehicles. The Commonwealth already has some of the nation’s most stringent emissions standards for light-duty vehicles. Those standards have helped to dramatically slow the growth of transportation emissions despite a steady increase in VMT consistent with a 14% increase in population since 1990. Massachusetts is also a leading state for electric vehicle (EV) rebates and incentives.

In the long-term, Massachusetts can achieve its 2050 GHG emissions goals by transitioning to electric or other "zero emission" vehicles, which are about three times more efficient than internal combustion vehicles. In addition, Massachusetts’ SmartGrowth policies encourage development in dense areas with maintained sidewalks and bike paths, and near transit hubs to reduce the need to drive long distances.

For a more detailed analysis of Massachusetts’ progress, please review the GWSA 10-Year Progress Report.


Direct Buildings Sector emissions are the result of burning fossil fuels to heat our homes and businesses and to provide important building services, such as hot, potable water. Indirect building emissions are related to electricity use for lighting, heating, and other building appliances. Massachusetts has consistently prioritized energy efficiency as a central component of the its clean energy policy and been ranked #1 in the US for energy efficiency for the last nine consecutive years.

Efficiency gains can be made both by appliances that use less energy to complete the same task as well as by reducing the need for energy, such as by improving insulation of buildings to reduce space heating and cooling needs. Increasingly, policies for managing energy demand in buildings will complement Massachusetts' policy of pursuing all cost-effective energy efficiency and demand reduction. These are likely to include improving building energy codes, adopting updated appliance standards, and rapidly accelerating the widespread adoption of renewable thermal and electric heating technologies.

For a more detailed analysis of Massachusetts’ progress, please review the GWSA 10-Year Progress Report.

Non-Energy Emissions

Massachusetts has made significant progress in reducing non-energy emissions, a category which includes many potent greenhouse gases such as methane (CH4), sulfur hexafluoride (SF6), and chloroflruorocarbons (CFCs) and hydrofluorocarbons (HFCs). Methane emissions from leaks in our natural gas distribution and piping system have been brought down rapidly since 1990, limits have been set on SF6 emissions, and recycling efforts are in place to decrease emissions from plastic incineration. However, since 1990 ozone-depleting substances (ODS), such as CFCs, have been replaced with refrigerants such as HFCs. While HFCs do not deplete ozone, they do have global warming potentials up to tens of thousands of times greater than CO2.

In June 2018, Massachusetts signed onto the U.S. Climate Alliance’s Short Lived Climate Pollutant Challenge, pledging to explore potential policies to reduce emissions of short lived climate pollutants, which include HFCs. 

For a more detailed analysis of Massachusetts’ progress, please review the GWSA 10-Year Progress Report.

Economy, Public Health, and other Benefits

As Massachusetts continues to decarbonize its energy systems, the Commonwealth's economy will continue to benefit. According to MassCEC’s 2018 Clean Energy Industry Report, the clean energy industry employs more than 109,000 people in Massachusetts and contributes $13.2 billion to the Commonwealth’s economy.

In addition, Massachusetts' climate policies are making the Commonwaelth a safer, healthier, and more resilient place to live and work. Burning fossil fuels for energy not only releases climate-altering carbon dioxide; it can releases large volumes of other pollutants, such as sulfur oxides (SOx), nitrogen oxides (NOx), particulate matter (PM, usually described as matter smaller than 10 or 2.5 microns: PM-10 and PM-2.5, respectively), and mercury (Hg). By accelerating our transition to clean and renewable energy sources, Massachusetts; GWSA policies have removed not just millions of tons of greenhouse gases, but also reduced thousands of tons of these dangerous criteria pollutants from our air and our waters, resulting in billions of dollars of public health benefits.

For a more detailed analysis of Massachusetts’ progress, please review the GWSA 10-Year Progress Report.