The transportation sector remains the largest-emitting sector in California by far, accounting for 40.7 percent of the total in 2019. The share declined slightly from 40.9 percent in 2018, but on-road passenger vehicles’ share actually rose from 27.8 percent to 28.5 percent of the state’s total GHG emissions. Similar to the previous year, the heavy-duty vehicles subsector (-7.5%) was the main contributor to the drop in GHG emissions from on-road vehicles.
GHG emissions from the commercial and residential sectors continue to climb despite an overall decreasing trend in total GHG emissions. In the five-year span from 2014 to 2019, these sectors’ share of GHG emissions rose from 4.8 percent to 5.8 percent for commercial and from 6.1 percent to 7.9 percent for residential. The main driver of GHG emission increases in these sectors was an increasing use of substitutes for ozone depleting substances (substitutes for ODS) for refrigeration and air conditioning activities.