The law requires the California Air Resources Board (ARB), no later than 1 January 2018, to approve and begin implementing a comprehensive strategy to reduce emissions of short-lived climate pollutants to achieve the targeted reductions.

Super pollutants have more potent heat-trapping effects but remain in the atmosphere for a shorter time than carbon dioxide. Black carbon, for example, has a global warming potential 3200 times that of CO₂ on a 20-year time scale. Reducing these pollutants can have a more immediate beneficial impact on climate change.

Black carbon, a component of soot, also known as PM _2.5, comes from diesel engines and incomplete burning of carbon sources. Wildfires contribute almost 50% of the total black carbon emissions in California.

Black carbon darkens the surface of snow and ice, which accelerates heat absorption and melting, and is thought be the second greatest contributor to global climate change, after CO₂. In addition to being a powerful global warming pollutant, black carbon is associated with numerous negative health impacts and is designated a potential human carcinogen.

Black carbon is not listed under California’s AB 32 as a greenhouse gas subject to AB32 regulations. However, due to known health and air quality impacts, ARB adopted truck and bus regulations in 2008 to control diesel PM emissions.

ARB also administers the Carl Moyer Program, which provides grants to fund “cleaner than required” engine upgrades, or retrofits that reduce PM_2.5 and other pollutants.

Removing one ton of diesel black carbon from the atmosphere, for example, is equivalent to removing 1,000 to 2,000 tons of carbon dioxide pollution. Worldwide, methane emissions alone are responsible for approximately 20 percent of current global warming.

The policies that California is implementing, if achieved worldwide, would cut the expected rate of global warming in half by 2050, save millions of lives, avoid millions of tons of crop losses per year and slow dangerous climate feedbacks such as melting ice caps and rising sea levels. The benefits of such a policy can far exceed the cost of enacting it.

—Scripps Institution of Oceanography Distinguished Professor Dr. Veerabhadran Ramanathan

California’s ongoing efforts to improve air quality and address climate change have already led to reductions in super pollutants, and provided a foundation for the new legislation. SB 605 by Senator Ricardo Lara (a co-author of SB 1383), signed by Governor Brown in 2014, directed the California Air Resources Board (ARB) to develop a comprehensive strategy for addressing super pollutants, which ultimately included reduction targets now set forth in this new legislation.

California has already cut black carbon emissions by more than 90% since the 1960s, has the nation’s strongest standards for limiting methane emissions from landfills and strictly regulates emissions from refrigerants, air conditioning and consumer products.