Log in | Subscribe | RSS feed

What’s New

California adopts bill to control emissions of short-lived climate pollutants

20 September 2016

California Governor Jerry Brown signed Senate Bill 1383 (SB 1383)—a climate change regulation to reduce emissions of short-lived climate pollutants, such as black carbon, fluorinated gases, and methane. The measure follows the recent climate change bills that mandate a reduction of California GHG emissions by 40% below the 1990 level by 2030.

Under bill SB 1383, the California Air Resources Board (ARB) is required, no later than January 1, 2018, to approve and begin implementing its Short-Lived Climate Pollutant Strategy to achieve a reduction in the statewide emissions of methane by 40%, hydrofluorocarbon gases by 40%, and anthropogenic black carbon by 50% below 2013 levels by 2030.

The the bill focuses on several sources and strategies of methane emission reduction:

Bill SB 1383 does not explicitly mention any additional measures to reduce black carbon (BC) emissions from diesel or other sources. The Proposed Short-Lived Climate Pollutant Strategy estimates that under existing measures, on-road diesel engines will contribute only 1% of California 2030 anthropogenic (non-forest) BC emissions. According to the estimate, the three dominant BC emission sources in 2030 will be (1) industrial fuel combustion, (2) fireplaces and woodstoves, and (3) off-road mobile sources—each contributing 24% of California BC emissions.

California’s 2030 anthropogenic (non-forest) black carbon emission with existing measures

Since 2007, all new highway diesel engines in the United States have been equipped with diesel particulate filters (DPF). Off-road diesel engines, on the other hand, can meet emission regulations without DPFs—some 50% or more of new US Tier 4 off-road engine families are emission certified without filters.

Some short-lived climate pollutants are significant contributors to the climate warming, but their lifespan in the atmosphere is short compared to that of CO2, which persists for hundreds of years. The warming effect of methane is 20-30 times stronger, per mole, than that of CO2, and CH4 can be responsible for as much as 20% of the global warming effect, but it's lifespan in the atmosphere is on the order of 10 years. The lifespan of black carbon is even shorter—on the order of months or weeks.

Due to their short lifespan, the control of short-lived GHG emissions can bring results within a short time frame. If followed worldwide, the emission reductions mandated by SB 1383 would help cut the projected rate of global warming in half by 2050, said Governor Brown.

Some of the short-lived climate pollutants are also toxic air contaminants, noted SB 1383. Efforts to reduce emissions should focus on areas of the state that are disproportionately affected by poor air quality.

Source: Governor Brown