California Air Resources Board

The 2020 GHG emission limit is 431 MMTCO₂e using IPCC Fourth Assessment Report GWPs

The Global Warming Solutions Act of 2006 (AB 32) requires that CARB determine the statewide greenhouse gas emissions level in 1990. The act also requires that the Board approve a statewide greenhouse gas emissions limit, equal to the 1990 level, as a limit to be achieved by 2020. This limit is an aggregated statewide limit, and is not sector- or facility-specific. The 2020 GHG emissions limit is 431 million metric tons of carbon dioxide equivalent (MMTCO₂e). In 2016, Senate Bill 32, California Global Warming Solutions Act of 2006: Emissions Limit (SB 32) further required California to reduce statewide GHG emissions to 40% below the 1990 level by 2030.

CARB Approval of Updated 2020 Limit

Calculation of the original 1990 limit approved in 2007 was revised in 2014 using the scientifically updated Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4) global warming potential (GWP) values, to 431 MMTCO₂e. The Board approved 431 MMTCO₂e as the 2020 emission limit with the approval of the First Update to the Scoping Plan on May 22, 2014.

Setting the Original 2020 Limit

During 2007, CARB staff developed a 1990–2004 greenhouse gas emission inventory to determine the 1990 emission level, which the Board approved as the 2020 limit of 427 MMTCO₂e. This value was based on IPCC second assessment report GWPs. The Board approved the 2020 limit on December 6, 2007. The Board materials associated with the original 2020 limit are available at the links below. This original value was updated in the 2014 Scoping Plan Update as discussed previously.

Staff Presentation for Board
Board Meeting Archive
Meeting Transcripts
Public Comments Received
Board Resolution

The staff report titled "California 1990 Greenhouse Gas Emissions Level and 2020 Emissions Limit" discusses the original development of the 1990 statewide emissions level and provides a summary of the key emissions sources, the methodologies used to calculate the emissions, and the sources of data. These methods use the original IPCC second assessment report GWPs.

Staff Report: California 1990 Greenhouse Gas Emissions Level and 2020 Emissions Limit
Appendix A-1: Summary 1990 Inventory by IPCC Category
Appendix A-2: 1990 Inventory by IPCC Category
Appendix B: 1990 Carbon Flux Table and Diagram
Appendix C: California Global Warming Solutions Act of 2006

Additional Resources

1990 Inventory Data, Reports & Documentation
1990 Inventory Query Tool