Short-Lived Climate Pollutants
Short-lived climate pollutants (SLCP) are powerful climate forcers that have relatively short atmospheric lifetimes. These pollutants include the greenhouse gases (GHG) methane and hydrofluorocarbons (HFC), and anthropogenic black carbon. Because SLCP impacts are especially strong over the short term, acting now to reduce their emissions can have an immediate beneficial impact on climate change and public health.
California’s Global Warming Solutions Act, Assembly Bill 32, charged the California Air Resources Board (CARB or Board) with reducing statewide GHG emissions to 1990 emission levels by 2020. Senate Bill (SB) 32 requires further GHG emissions reductions of 40 percent below 1990 emission levels by 2030.
SLCP emissions reductions will support achieving these targets. SB 605 directed CARB, in coordination with other State agencies and local air districts, to develop a comprehensive SLCP reduction strategy, and SB 1383 directed CARB to approve and begin implementing this strategy. This legislation also set statewide emissions reduction targets specifying a 40 percent reduction in methane, a 40 percent reduction in HFCs, and a 50 percent reduction in anthropogenic black carbon below 2013 levels by 2030. The bill also established specific targets for reducing organic waste in landfills and provided specific direction for methane emissions reductions from dairy and livestock operations.
The SLCP Reduction Strategy, approved by the Board in March 2017, lays out a range of options to reduce SLCP emissions in California, including regulations, incentives, and other market-supporting activities. The SLCP Strategy also informed the Final 2017 Scoping Plan Update.
The strategies in regard to the three SLCPs are as follows:
Methane is a powerful GHG, the emissions of which are responsible for about 20 percent of the global warming now driving climate change. Over half of the methane emissions in California come from dairy and livestock manure and enteric fermentation (the latter mostly from burping). The remaining methane is from landfilled organic waste streams and fugitive emissions from oil production, processing, and storage; the gas pipeline system; and industrial operations. California can reduce methane emissions 40 percent by 2030 through capturing or avoiding methane from manure at dairies, reducing methane from enteric fermentation, reducing disposal of organics at landfills, and reducing fugitive methane emissions.
SB 1383 requires CARB, in consultation with the California Department of Food and Agriculture (CDFA), to adopt regulations to reduce methane from dairy and livestock manure management operations. A regulation can be implemented no earlier than 2024 and only if certain conditions are met. SB 1383 also required CARB to work with a broad range of stakeholders to identify and address challenges and barriers to the development of dairy methane emissions reduction projects. To accomplish this, CARB, CDFA, California Energy Commission, and California Public Utilities Commission convened a Dairy and Livestock Greenhouse Gas Emissions Reduction Working Group in May 2017; this work ended in December 2018.
For organic waste that is currently landfilled, CalRecycle, in consultation with CARB, is developing a regulation to achieve a 50 percent reduction in statewide disposal of organic waste by 2020 and a 75 percent reduction by 2025, including efforts to reduce edible food waste using methods that may include redistribution and composting.
The SLCP Reduction Strategy also establishes a goal of reducing fugitive methane emissions from oil and gas by 40 percent below current levels in 2025 and a minimum 45 percent in 2030, and from all other sources by 40 percent in 2030.
Fluorinated gases—especially HFCs—are the fastest-growing source of GHG emissions both in California and globally. More than three-quarters of HFC emissions in California come from the use of refrigerants in the commercial, industrial, residential, and transportation sectors.
CARB has already adopted measures to reduce HFC emissions: the Refrigerant Management Program, low-global warming potential air conditioning for motor vehicles, prohibition of HFCs as aerosol propellants in consumer products, reduction of fluorinated gases in semiconductor manufacturing, and a Cap-and-Trade Program compliance offset protocol for the capture and destruction of ozone depleting substances.
Additionally, in March 2018, CARB adopted a California Significant New Alternatives Policy (SNAP) Regulation, which preserves and continues some of U.S. EPA’s prohibitions on HFCs.
Emissions reductions from on-road diesel engines will almost completely eliminate black carbon emissions from on-road sources within the next ten years. These reductions will result in other sources becoming proportionally more significant contributors to anthropogenic black carbon emissions over time. Those sources include off-road mobile vehicles, fuel combustion in industry and power generation, and woodburning stoves and fireplaces, which will account for more than three-quarters of anthropogenic black carbon emissions in California in 2030. Continued progress on transitioning to cleaner and more efficient uses of energy, reducing fireplace and woodstove emissions, and developing and implementing a sustainable freight system will continue to reduce anthropogenic black carbon emissions and aid in meeting the SLCP Reduction Strategy targets.