California is working to reduce greenhouse gas (GHG) emissions across all sectors of the economy, under the framework of Assembly Bill 32 (2006) and Senate Bill 32 (2016). In addition, California has established several other mandates to reduce the statewide emissions of greenhouse gases, including Executive Order S-3-05, Senate Bill 605 (2014), Assembly Bill 1496 (2015), and Senate Bill 1383 (2016).
Although carbon dioxide (CO2) emissions constitute the largest share of California’s inventory, nitrous oxide, and short-lived climate pollutants, such as methane, HFCs, and black carbon, are also significant contributors to California's greenhouse gas emission inventory.
Methane is an important greenhouse gas, which is responsible for about 20 percent of current global warming, and is a contributor to harmful ground-level ozone. According to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), methane has 28 times greater impact than CO2 over a 100-year timespan, and 84 time greater impact than CO2 over a 20-year timespan. Methane emissions also continue to increase globally.