In January 2007, Massachusetts joined the Regional Greenhouse Gas Initiative (RGGI), a cooperative effort by Northeast and Mid-Atlantic states to reduce emissions of carbon dioxide, a greenhouse gas that contributes to global climate change.

To address this important environmental issue, RGGI and its member states have developed a regional strategy for controlling emissions, including a market-based, multi-state cap-and-trade program that requires electric power generators to reduce their emissions of carbon dioxide.

To address this important environmental issue, RGGI and its member states have developed a regional strategy for controlling emissions, including a market-based, multi-state cap-and-trade program that requires electric power generators to reduce their emissions of carbon dioxide.