Note: an update to this chart is available. For the latest information, go to U.S. Climate Targets.


This analysis provides an assessment of reductions in greenhouse gas (GHG) emissions that could be achieved by Title III of the amendment in the nature of a substitute to H.R. 2454, the American Clean Energy and Security Act (ACESA) sponsored by Chairmen Waxman and Markey released on May 19, 2009. This assessment is an update to a previous analysis released on April 21, 2009 and reflects a significantly revised reference case recently released by the Environmental Protection Agency. To account for the effects of different components of H.R. 2454, reduction estimates are divided into three scenarios:

  • Total emission reductions under just the two proposed emissions caps (the cap on hydrofluorocarbon (HFC) consumption and the economy-wide cap).
  • Total emission reductions under the caps and all other complementary requirements, including emission performance standards for uncapped sources and required components of the supplemental reduction program through 2025.
  • A range of potential additional reductions that could be achieved through the 1.25 offset requirement for international offsets and supplemental reductions beyond 2025.

Key findings:

  • The pollution caps proposed in the ACESA would reduce total GHG emissions 15 percent below 2005 levels by 2020 and 73 percent below 2005 levels by 2050.
  • When all complementary requirements of the ACESA are considered in addition to the caps, GHG emissions would be reduced 28 percent below 2005 levels by 2020 and 75 percent below 2005 levels by 2050.
  • When additional potential emission reductions are considered, the ACESA could achieve maximum reductions of up to 33 percent below 2005 levels by 2020 and up to 81 percent below 2005 levels by 2050. The actual amount of reductions will depend on the quantity of international offsets used for compliance.
  • The ACESA‚Äôs proposed pollution caps result in reductions of total GHG emissions of 15 percent below 2005 levels by 2020. This is less than the 17 percent reduction from 2005 levels that the Waxman Markey Discussion Draft as released would have achieved.