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Seattle Releases 2020 Greenhouse Gas Inventory Report Showing Pandemic-Spurred Declines in Building and Transportation Sector Emissions

Seattle’s 2020 Greenhouse Gas (GHG) inventory finds a marked decrease in greenhouse gas emissions since the prior 2018 report, the majority of which are likely temporary and primarily attributed to the impacts of the COVID-19 pandemic. The Seattle GHG inventory tracks emissions over three key sectors: transportation, buildings, and waste.

Key findings include:

Transportation (24.5% decrease in emissions)

  • People drove significantly less in 2020 primarily due to COVID-19 stay-at-home orders, resulting a 20% decrease in both passenger and freight vehicle miles traveled (VMTs).
  • Public transit was especially hard hit, and traffic monitors show vehicle volume and personal vehicle travel patterns returning to baseline.
  • Vehicles are becoming more efficient, showing a 5% decrease in emissions per mile.

Buildings (5% decrease in residential and commercial emissions)

  • All core building emissions categories decreased but residential energy use increased by 3%, which accounts for the increase in time spent at home as residents who were able adhered to stay-at-home orders and continued working from home.
  • Seattle’s buildings also got more efficient, consuming 5% less energy per capita after normalizing for weather, a trend that is expected to continue, and Seattle City Light’s emissions factors changed as the utility reported a resource portfolio with less carbon-intensive electricity.
  • As with transportation emissions, building emissions are expected to rebound in future years.

Waste (12.4% decrease in emissions)

  • The major factors contributing to the reduction in waste emissions were a decrease in commercial waste due to the pandemic, and a new residential waste composition study, which shows a lower percentage of recyclable and compostable materials entering the garbage stream.
  • Waste emissions account for just 1.2% of total core emissions, but SPU’s consistent efforts to improve the composition of municipal solid waste have led to a 35.5% reduction in emissions since 2008. 

While the 2020 emissions data show declines in emissions due to the pandemic, Seattle’s 2018 inventory showed emissions increased 1.1% since the last report, and without additional action the City projects emissions will not only rebound to pre-pandemic levels but also continue this upward trend. This week, Seattle Mayor Bruce Harrell will travel to Buenos Aires to participate in the C40 World Mayors Summit, where mayors and climate leaders from around the world will unite to share their plans, efforts, and experiences to accelerate delivery of climate action and commitments. 

“It’s not a surprise that drastic drops in our emissions followed the drastic changes in people’s lives over the last several years. But as we recover, we must recognize and act on the need for bigger, bolder, and more equitable climate action,” said Seattle Mayor Bruce Harrell. “Meaningful action on climate change requires collaboration at the highest levels – including global networks like the C40 Climate Alliance –where we can learn and share impactful climate mitigation and adaptation strategies. I look forward to these important conversations, aligning with fellow mayors at the C40 Mayor’s Summit to bring home renewed urgency and new ideas to drive emission reductions, bolster a growing clean energy economy, and build healthy and resilient communities.” 

Seattle conducts GHG inventories on a biennial basis (every two years) to report on the sources and magnitude of GHG emissions and visualize trends to inform climate policy and program development. Other jurisdictions follow a similar reporting cadence; in early October King County published their Puget Sound Regional Emissions Analysis providing updated data for multiple jurisdictions through 2019 and in some cases 2020.

“We stand here with two paths to take – we can continue business as usual and see emissions steadily tick back up to pre-pandemic levels where we were trending in the wrong direction, or we can take this opportunity to learn from the past and engage in learning and strategizing to help us change how we design policies to make them more effective and equitable for those hit hardest by the climate crisis,” said Jessyn Farrell, Director, Office of Sustainability & Environment. “Through the framework of Mayor Harrell’s One Seattle Climate Justice Agenda and Green New Deal for Seattle, we are making investments and commitments to community to meet the challenge of climate change in Seattle in a way that builds resilience against current climate impacts and paves the way for a clean energy future.”

While this inventory provides us a broad understanding of how our emissions are trending, it is not detailed enough in scope or depth to use as the primary source for making decisions that center racial equity. As called for in the Green New Deal Resolution (Res 31895) to address these gaps, OSE is developing a map-based website which will be updated on a quarterly basis to provide more frequent and granular data indicators of emissions in Seattle’s neighborhoods. The “One Seattle Climate Portal” will be released by the end of 2022. Beginning in 2023 the City will develop the next phase of the portal which will incorporate community led data efforts, as well as ways to spatially track city-led investments.

“Greenhouse gas inventories are an important tool to track our climate emissions and identify trends in climate emissions, but they are also limited by the lag in data collection and lack of specificity of emissions by neighborhood where we know from other health indicators that climate impacts and pollution is worse in certain parts of the City,” said Ani Krishnan, Climate Data & Policy Manager, Office of Sustainability & Environment. “The GHG inventory tells us how much emissions there were, but the One Seattle Climate Portal will come in to show us where the pollution is occurring. I look forward to being able to share with residents, for the first time, emissions data spatially, on a map where we can see in which neighborhoods emissions are occurring and make decisions that center racial equity.” 

The City of Seattle is accelerating several significant policies and programs to reduce emissions from buildings, including building emission performance standards and the clean heat program, which are projected to reduce building emissions by 35%. The City is also innovating with policies and programs aimed at reducing emissions from transportation, including infrastructure to increase walking, biking and transit use in the City, electrifying vehicles that move people, goods and services, and improving air quality in fence line communities. More information can be found at