Washington's greenhouse gas inventory

The greenhouse gas inventory is the historical record of Washington's contribution to global climate change. It estimates statewide emissions and measures reductions compared to a 1990 baseline. This helps policymakers track progress toward meeting our state's legal limits on greenhouse gas emissions.

As required by law, we publish an inventory report every two years. Our current inventory includes data through 2021. The next inventory will be published by December 2026 and include data through 2023.

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Greenhouse gas inventories

Data shows that Washington's greenhouse gas emissions decreased from 2019 to 2020 and partially rebounded in 2021:

2021 total emissions — 96.1 million metric tons
2020 total emissions — 88.3 million metric tons
2019 total emissions — 102.1 million metric tons

Washington State Greenhouse Gas Emissions Inventory: 1990–2021

Like most states that compile statewide emission inventories, we rely primarily on data from the Environmental Protection Agency's (EPA) State Inventory Tool to build this report, which lags by several years.

We're working to provide more frequent emissions updates and decrease the lag time between emissions data and inventory publication by building a team that identifies and collects in-state data to replace, and supplements what we currently receive from the EPA.

2021 Washington greenhouse gases: 24.7% buildings; 39.7% transportation; 19.5% electricity; 16.1% other

Greenhouse gas emissions for 2020-2021

Washington's current greenhouse gas inventory shows emissions dipped 13.8% in 2020, falling below the legal limit for that year. Emissions rose 8.8% in 2021 but stayed below 2019 levels.

The partial emissions rebound in 2021 was driven by the transportation sector following the height of the COVID-19 pandemic, underscoring the importance of new state policies designed to promote clean transportation: the Clean Fuel Standard and zero-emission vehicle standards.

The increase in transportation emissions was largely driven by non-highway sources, such as planes, boats and trains. Emissions from passenger cars and trucks remained well below pre-pandemic levels in 2021 — a sign that remote work altered commuting patterns — and are expected to decrease further. Washingtonians are adopting electric and plug-in hybrid vehicles at record rates, and zero-emission vehicle standards will accelerate this trend.

The electricity sector made the most progress from 2019 to 2021, with emissions dropping nearly 15%. These gains were driven by record wind and solar production, alongside significantly lower coal and natural (methane) gas usage. An uptick in hydropower production also played a role. The Clean Energy Transformation Act, which took effect in 2021, will drive down emissions from this sector in the future by requiring electric utilities to transition to 100% clean electricity by 2045.

Sources of Washington greenhouse gases in 2021

Transportation was the largest category of greenhouse gas emissions in Washington in 2020 and 2021. This category includes emissions from on-road gasoline and diesel vehicles, marine vessels, jet fuel and aviation gasoline, railroads, and natural gas used in transportation.

Though transportation emissions rose from 2020 to 2021, they remained lower than they were in 2019. Overall, transportation emissions dropped by 5% between 2019 and 2021.

• 39.7% of total Washington emissions
• 38.2 million metric tons of emissions

Learn more about how we’re helping reduce greenhouse gases from transportation.

At 24.7%, fossil fuel-based heating for buildings is still Washington's second largest source of greenhouse gas emissions. From 2020 to 2021, building emissions declined 0.6% to 23.7 MMT CO2e. We expect to see building emissions drop even further in future inventories after new building performance standards and energy codes take effect.

Emissions in this sector come from burning fuels for heating homes and workplaces, and energy used by industries. This category includes heat generated from coal, natural gas, and oil.

• 24.6% of total Washington emissions
• 23.7 million metric tons of emissions

Learn more about how we’re helping reduce greenhouse gases from residential, commercial, and industrial heating.

Electricity emissions dropped 14.6% from 2019 to 2021, the biggest decrease of any sector during that timeframe. This category includes emissions from power generated from coal, natural gas, petroleum, and waste.

In Washington, about 80% of Washington's electricity comes from renewable or clean energy. The remaining 20% comes from coal and natural (methane) gas.

The Clean Energy Transformation Act (CETA), which took effect in 2020, was a major driver of the drop in electricity emissions, which requires all electric utilities to transition to 100% clean electricity by 2045.

• 19.5% of total Washington emissions
• 18.7 million metric tons of emissions

Learn more about how we're helping reduce greenhouse gases from electricity generation.

Agriculture — 6.6 million metric tons

Agricultural activities such as manure management, fertilizer use, and livestock digestion (enteric fermentation) result in methane and nitrous oxide emissions, which are measured in this category.

• 7.6% of total Washington emissions
• 6.6 million metric tons of emissions

Industrial processes — 4.3 million metric tons

This sector includes greenhouse gas emissions from industry-specific processes such as aluminum or cement manufacturing, or fugitive emissions such as sulfur hexafluoride (SF6) released from electric power transmission and distribution systems.

• 5.1% of total Washington emissions
• 4.3 million metric tons of emissions

Waste management — 3.2 million metric tons

This sector includes greenhouse gas emissions from landfills and wastewater treatment facilities.

• 3.5% of total Washington emissions
• 3.2 million metric tons of emissions

Fugitive fossil fuels — 1.4 million metric tons

This sector includes fugitive greenhouse gas emissions that are released during distribution of fossil fuels. These emissions are typically fugitive methane due to leakage and venting from natural gas pipelines.

• 1.1% of total Washington emissions
• 1.4 million metric tons of emissions

Greenhouse gas limits

The Washington State Legislature passed a strong suite of climate policies to reduce greenhouse gas emissions to net zero by 2050. Our current greenhouse gas inventory includes data through 2021, before most of these policies had been implemented. The collective impact of these policies will show up in future inventories.

graph showing actual emissions and future goals from 1990 to 2021

Washington set legal limits on greenhouse gas emissions for 2020, 2030, 2040, and 2050. These limits are based on scientific recommendations about what is necessary to prevent the worst effects of climate change on our state's environment and economy.

History of greenhouse gas emissions in Washington

Greenhouse gas emissions in Washington peaked in 2000, at just over 111 million metric tons. Following the Great Recession in 2008, emissions declined sharply for several years before slowly climbing back up to 102.1 million metric tons in 2019.

At 96.1 million metric tons, 2021 emissions were 14% below the historical peak that occurred in 2000. Moving forward, we expect to see steeper declines in emissions as a result of Washington’s comprehensive set of climate policies.

Contact information

Caroline Halter

Communications Manager

Caroline.Halter@ecy.wa.gov

564-669-8947