On August 7, 2008, Massachusetts Governor Deval Patrick signed into law the Global Warming Solutions Act, S2540, which requires the Commonwealth to reduce its greenhouse gas emissions at least 80 percent below 1990 levels by 2050. The bill calls for the Secretary of Energy and Environmental Affairs to set an interim target of between 10 and 25 percent below 1990 levels by 2020, as well as targets for 2030 and 2040. Previously, the Commonwealth had reduction goals of 1990 levels by 2010 and 10 percent below 1990 levels by 2020, with a long-term goal of reducing emissions to avoid dangerous climate change.
The Massachusetts Department of Environmental Protection is responsible for determining 1990 baseline emission and calculating 2020 “business as usual” levels, assuming no action is taken. A plan to achieve the 2020 limit shall be adopted by January 1, 2011, with market-based mechanisms to be considered as a method for achieving these targets.