This page last reviewed August 9, 2016

Reducing Short-Lived Climate Pollutants in California

What are Short-Lived Climate Pollutants?

Short-lived climate pollutants are powerful climate forcers that remain in the atmosphere for a much shorter period of time than longer-lived climate pollutants, such as carbon dioxide (CO₂). Their relative potency, when measured in terms of how they heat the atmosphere, can be tens, hundreds, or even thousands of times greater than that of CO₂. The impacts of short-lived climate pollutants are especially strong over the short term.  Reducing these emissions can make an immediate beneficial impact on climate change.

Short-Lived Climate Pollutants include three main components:

• Black carbon is a component of fine particulate matter, which has been identified as a leading environmental risk factor for premature death. It is produced from the incomplete combustion of fossil fuels and biomass burning, particularly from older diesel engines and forest fires. Black carbon warms the atmosphere by absorbing solar radiation, influences cloud formation, and darkens the surface of snow and ice, which accelerates heat absorption and melting. Diesel particulate matter emissions are a major source of black carbon and are also toxic air contaminants that have been regulated and controlled in California for several decades in order to protect public health. 

• Fluorinated gases (F-gases) are the fastest growing source of greenhouse gas emissions in California and globally. They include ozone-depleting substances that are being phased out globally under the Montreal Protocol, and their primary substitute, hydrofluorocarbons (HFCs). Most F-gas emissions come from leaks of these gases in refrigeration and air-conditioning systems. Emissions also come from aerosol propellants, fire suppressants, and foam-expansion agents. 

• Methane (CH₄) is the principal component of natural gas. Its emissions contribute to background ozone in the lower atmosphere (troposphere), which itself is a powerful greenhouse gas and contributes to ground level air pollution. The atmospheric concentration of methane is growing as a result of human activities in the agricultural, waste treatment, and oil and gas sectors. Capturing methane from these sources can improve pipeline safety, and provide fuel for vehicles and industrial operations that displaces fossil natural gas use.

The Short-Lived Climate Pollutant Strategy

SB 605 (Lara, Chapter 523, Statutes of 2014) directed ARB to develop a comprehensive short-lived climate pollutant strategy, in coordination with other state agencies and local air quality management and air pollution control districts. The effort is to engage scientific experts, identify additional measures to reduce short-lived climate pollutants, and will build upon California’s leading commitments to reduce greenhouse gases and air pollution. Furthermore, Governor Brown has identified reductions of  SLCP emissions as one "pillar" to meet an overarching goal to reduce California's GHG emissions by 40 percent below 1990 levels by 2030. ARB staff released a proposed SLCP Strategy in April 2016 and will present the Final SLCP Strategy to the Board for approval later this year.

SLCP Documents

• Proposed Strategy (posted April 11, 2016)

• Appendix A: California SLCP Emissions
• Appendix B: Research Related to Mitigation Measures
• Appendix C: Draft Environmental Analysis for the Proposed SLCP Reduction Strategy
• Appendix D: Supporting Documentation for the Economic Assessment of Measures in the Proposed Strategy

Archived Meetings and Documents Portal

Staying in Touch

To receive electronic notices of future meetings and availability of materials, you can sign up with the climate change list server at:  http://www.arb.ca.gov/listserv/listserv_ind.php?listname=cc