Total greenhouse gas (GHG) emissions declined by 35.27 million metric tons of carbon dioxide equivalent (MMTCO2e) to 369.2 MMTCO2e in 2020, or an 8.7 percent decrease compared to 2019. This also represents 14.3 percent below the 1990 level of 431 MMTCO2e.
By top-level economic sector, the Transportation sector saw the largest reduction in GHG emissions from 2019 to 2020 (-16.1%), followed by a 14.1 percent decrease in the Electricity Power Generation from Imports sector. The Industrial sector saw a 7.5 percent decrease (includes Manufacturing & Petroleum Refining and Hydrogen Production), while the Commercial sector (Hotels & Food Services) also decreased by 4.1 percent.
GHG emissions rose in only two other economic sectors in 2020 compared to 2019: Agriculture & Forestry (+0.7%), and Electricity Power Generation from In-State (+6.3%).
The transportation sector remains the largest-emitting sector in California by far, accounting for 37.9 percent of the total in 2020. This share declined from 41.2 percent in 2019.
On the other hand, GHG emissions from the commercial and residential sectors have continued to climb over the last several years despite decreasing total GHG emissions. In the four years from 2016 to 2020, these sectors’ share of GHG emissions rose from 5.2 percent to 6.0 percent for commercial and from 6.6 percent to 8.3 percent for residential—a further increase from 5.7 percent and 7.6 percent captured in 2019, respectively.
While emissions from the in-state electric power sector increased from 2019 to 2020 (+6.3%), this sector has experienced dramatic reductions over time. Emissions from in-state generation were down by 30.6 percent and by more than half (-59.5%) for imports in 2020 compared to 2000 levels. Emissions in the electric power sector from both in-state and imports decreased by 1.1% from 2019 to 2020, driven by a 14.1 percent reduction in emissions from imports.
The majority of the increase in emissions from the in-state electricity generation were from the Merchant Owned (+1.8%) and Transmission and Distribution (+33.1%) subsectors. As the grid becomes cleaner—while threats from natural disasters such as drought (which reduce electricity generation from hydropower) and wildfires persist—further emission cuts may become more difficult.