Total greenhouse gas (GHG) emissions increased by 12.6 million metric tons of carbon dioxide-equivalent (MMTCO₂e) to 381.3 MMTCO₂e in 2021—representing a 3.4 percent increase compared to 2020. However, 2021 emissions remained 5.7 percent lower (-23.1 MMTCO₂e) than the 2019 pre-pandemic level of 404.41 MMTCO₂e.

The 2021 GHG emissions were 11.5 percent below the 1990 level of 431 MMTCO₂e. From 2000 to 2021, total GHG emissions in California have decreased by 17.4 percent. Compared to the pre-pandemic amount in 2019, emissions decreased by 5.7 percent in 2021.

The transportation sector continues to be the predominant source of emissions in California, comprising 38.2 percent of the total emissions in 2021. This represents a slight increase from 36.8 percent in 2020 and a marginal decrease from 40.1 percent in 2019.

State data² reported 372 wildfires in California, totaling approximately 2.5 million acres, in 2021. These wildfires released an estimated 85.1 million metric tons from carbon dioxide (CO₂)³ in 2021, down from 106.7 million metric tons in 2020. This represents a 20.2 percent decrease from 2020 to 2021. Particulate matter emissions (PM 2.5 and PM 10) each decreased by 9 percent from 2020 to 2021. The smoldering phase saw a 7 percent reduction in fuel consumption, leading to lower PM10 emissions.

Compared to the GHG emissions in 2020, the residential sector experienced the largest reduction, decreasing by 2.3 percent. Emissions in the sector decreased for the second consecutive year in 2021, when the rate of reduction remained the same in both years (decreased by 0.6 MMTCO₂e in 2020 and 2021).

The agriculture sector closely followed with a decline of 2.1 percent from 2020 to 2021.

Emissions from the heavy-duty vehicles sub-sector decreased as well, with a 1.6 percent reduction from 2020 to 2021—making 2021 the third consecutive decrease since 2018. Emissions from the recycling & waste sector also decreased by 1.7 percent from 2020.

Conversely, GHG emissions from several sectors increased in 2021 compared to 2020. The transportation sector experienced the largest increase of 7.4 percent, followed by the electric power sector which increased by 4.8 percent, while the commercial sector saw an increase of 3.7 percent. Industrial sector GHG emissions were up 0.9 percent, while the high global warming potential (GWP) sector remained unchanged from 2020.

Within the electric power sector, both in-state generation and imports saw increased GHG emissions in 2021. The imports sub-sector led with an increase of 6.7 percent, followed by in-state generation, which increased by 3.9 percent from 2020.

In comparison to the pre-pandemic 2019 emissions, the transportation sector experienced the most substantial reduction with a decrease of 10.2 percent. The primary factor behind this reduction in transportation emissions was from the passenger vehicles sub-sector that saw a decline of 10.4 percent.

From 2019 to 2021, the industrial sector closely followed with a decline of 8.6 percent. Emissions in the commercial and residential sectors declined as well, with the commercial sector decreasing by 4.5 percent, and the residential sector decreasing by 4.4 percent. Additionally, GHG emissions from the agriculture sector fell by 1.5 percent compared to the 2019 levels.

On the flip side, certain sectors experienced an uptick in emissions from 2019 to 2021. Electric power saw the largest increase among all sectors, where it increased by 3.5 percent. Within the electric power sector, in-state generation emissions grew by 10.3 percent, while the emissions from imports decreased by 8.5 percent.

The high global warming potential gases (high-GWP gases) sector also registered an increase of 2.7 percent.

Additionally, the GHG emissions from the recycling and waste sector remained unchanged in 2021 compared to 2019.

As a share of total emissions, the residential sector decreased to 6.5 percent in 2021 compared to the 6.9 percent in 2020. Meanwhile, the commercial sector saw a marginal increase to 3.68 percent, up from 3.67 percent in 2020. However, the share of total emissions in both the residential and commercial sectors increased from 2019. By absolute terms, there was a 0.1 percent rise in the residential sector's share from the 2019 level of 6.4 percent and a 0.05 percent increase in the commercial sector's share from the 2019 level of 3.63 percent.

Over the five-year period from 2016 to 2021, the residential sector's share of total emissions grew from 5.9 percent to 6.5 percent, and the commercial sector's share increased from 3.5 percent to 3.7 percent.

Despite the increase in 2021, the electric power sector has seen dramatic reductions since 2000—down by 40.5 percent total since 2000. Within the sector, emissions from in-state generation fell by 27.7 percent and from imports were lower by 56.8 percent.

In order to meet the SB 32 goal of 40 percent below 1990 levels by 2030, the state would have to reduce its emissions by 4.4 percent a year starting in 2022, based on its 2021 GHG emissions. This is compared to the 4.2 percent annual decrease required in 2019 and the 3.6 percent annual decrease required in 2020. The requirement increased by 0.2 percent in 2021 compared to 2020 as pandemic travel restrictions eased and the economy re-opened.

At the current annual average rate of decrease over the most recent five-year period (2016-2021), which was an average of 1.6 percent each year, the state must increase emissions reductions in order to meet the 2030 and 2050 goals on time. Preliminary estimates of 2022 GHG emissions⁴ are projected to be 370.4 MMTCO₂e,⁵ which would be a decrease of 2.8 percent (10.9 MMTCO₂e) from total 2021 GHG emissions. However, the amount for 2022 is likely to change when the official inventory numbers are released in 2024.

In California, GHG emissions per capita increased by 4.2 percent (+0.39 MMTCO₂e/person) from 2020 to 2021, while the state’s inflation-adjusted GDP per capita grew by 8.6 percent over the same time period.

Compared to 2019, GHG emissions per capita in 2021 were down by 5.1 percent (-0.52 MMTCO₂e/person), while the inflation-adjusted GDP per capita in 2021 was up by 6.1 percent, respectively.

From 2011 to 2021, California’s energy intensity decreased by 32.1 percent, ahead of all of the other most populous states: Texas (-22.1%), Pennsylvania (-23.4%), New York (-24.8%), Florida (-27.6%), Illinois (-27.6%) and Ohio (-29.0%). However, it is behind Massachusetts (-33.5%).

In addition to performing well in terms of carbon intensity, California also has one of the lowest energy-related GHG emissions per capita levels, with 8.3 MMTCO₂e per person in 2021—edging out every other larger state except for New York (7.9 MMTCO₂e per person) and Massachusetts (8.0 MMTCO₂e per person).

After the large decline in emissions in 2020 (-8.8%) due to the COVID-19 pandemic, the carbon intensity of California’s energy supply (CO2 relative to British thermal unit) rose by 0.4 percent in 2021, which is less than other populous U.S. states: Florida (+1.6%), New York (+4.7%), Illinois (+4.5%) and Pennsylvania (+3.5%). However, it is more than Texas (-0.2%) and Ohio (+0.3%). In 2021, California's carbon intensity was 8.8 percent lower than that of the rest of the U.S.

Within the transportation sector, GHG emissions from on-road vehicles increased by 7.5 percent from 2020 to 2021. Most of the increase in emissions came from the passenger vehicles sub-sector, which increased by 10.6 percent. Additionally, the aviation, rail and ships sub-sector increased by 7.2 percent compared to 2020.

GHG emissions from heavy-duty trucks declined by 1.8 percent from 2020 to 2021. In fact, emissions from heavy-duty vehicles have continuously declined every year since 2018. When compared to the 2019 levels, heavy-duty vehicle emissions were 9.1 percent in 2021.

All of the sub-sectors within the transportation sector had lower emissions in 2021 than the pre-pandemic level in 2019. Overall, total emissions in the transportation sector were 10.2 percent (-16.6 MMTCO₂e) lower in 2021 than the 2019 total emissions of 162.3 MMTCO₂e. The passenger vehicle sub-sector has had the largest decline in emissions, decreasing by 10.4 percent from 2019 levels. This is followed by the heavy-duty vehicles sub-sector, which declined by 9.5 percent. The aviation, rail and ships sub-sector fell by 8.7 percent), and the off-road and unspecified sub-sector declined by 23.4 percent compared to 2019.

On-road light-duty vehicles (passenger cars, light-duty trucks & SUVs, and motorcycles) accounted for the lion’s share of the transportation sector’s emissions with 104.4 MMTCO₂e altogether. Despite the increase of 10.5 percent (+9.9 MMTCO₂e) in this sector in 2021 compared to 2020, this represents 71.7 percent of the transportation sector’s total emissions in 2021, up from 2020’s 69.7 percent.

GHG emissions from fuel combustion of biogenic materials (including biofuels and other biogenic energy sources) for on-road transportation have been rapidly increasing, up 211.8 percent in 2021 compared to 2008. It rose sharply in 2021, jumping by 27 percent from 2020 (which had decreased by 10.9% from 2019). However, rising GHG emissions from fuel combustion of biogenic materials isn't necessarily negative because emissions from biogenic materials don't permanently or irreversibly raise the atmospheric concentration of greenhouse gases.

In 2021, GHG emissions from substitutes for ODS from all economic sectors accounted for 5.4 percent of total included statewide emissions, down from 5.6 percent in 2020 but up from 5.0 percent in 2019. Total GHG emissions from substitutes for ODS are considerably larger in 2021 than 2011 (3.2%) and 2000 (1.2%).

Californians exported or sent 39.9 million tons of waste to landfills in 2021, up 1.5 million tons from 2020, but down 2.7 million tons from 2019. The increasing amount of waste sent to landfills also means California’s recycling rate has been falling since 2014; 2020’s recycling rate was 40 percent, down from 42 percent in 2021 but up 3 percent from 2019’s recycling rate of 37 percent. This represents just a little over half of the 75 percent recycling rate goal defined by AB-341.