USGS: Greenhouse gas emissions from federal lands trended mostly downward since 2009 peak

Reston, Va. - The USGS recently released a new report analyzing greenhouse gas emissions - including carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O) - associated with U.S. federal lands.

Published as a follow-up to an earlier USGS 2018 report, it incorporates the latest data and methodologies, expanding the timeframe of analysis from 2005 to 2022 while providing updated estimates of ecosystem carbon emissions and sequestration.

Given that U.S. federal lands are approximately 28% of the land in the United States, understanding both greenhouse gas emissions and sequestration on these lands is essential to informing land management practices that can mitigate greenhouse gas emissions.

"More than a quarter of lands in the United States are federally-managed, and almost one-quarter of the nation's greenhouse gas emissions come from federal lands. This report is key to understanding greenhouse gas emissions trends related to federal land and resource management," said Dave Applegate, USGS Director. "USGS science informs the work of resource managers whether from the oil and gas industry or ecosystem restoration specialists on public lands."

The first part of the report looks at emissions originating from the extraction and end use of fossil fuels from federally-managed rights, both below the land's surface and offshore areas including the Gulf of Mexico and the Pacific outer continental shelf. The findings include:

• On average, CO₂ emissions from federal lands comprise about 21.8% of the U.S. total.
• Overall, greenhouse gas emissions associated with federal lands declined from 2005 to 2022. Combined greenhouse gas emissions (CO₂, CH₄ and N₂O) in 2005 were 1368.2 million metric tons of CO₂ equivalent, falling to 1118.9 of CO₂ equivalent in 2022.
• The trend in declining emissions associated with federal lands mirrors the overall drop in emissions across the U.S.
• To date, peak fossil fuel production and emissions associated with federal lands both took place around 2009. Within the overall downward trend, there was an increase from 2020 to 2022.

"It is too early to tell if the increase after 2020 was just a short-term anomaly related to the pandemic, when emissions dipped and then rebounded, or if emissions will continue to trend upwards," said Matthew Merrill, USGS research geologist and lead author of the report.

The second part of the report provides an in-depth analysis of how ecosystems on federally-managed surface lands both emitted and sequestered greenhouse gases from 2005 to 2021.

Using the latest scientific methods, researchers found that ecosystems provided less of an offset than previously thought. In the original report looking at the years 2005 to 2014, ecosystem offsets were originally reported at 15%, but newer estimates using data from 2005 to 2021 show the average annual offset was just 1.4%.

While federal ecosystems functioned as net carbon sinks in 11 out of 17 years studied, climate factors such as drought and increased wildfires contributed to net emissions during six of the years studied. Combustion emissions reached nearly three times the historical average during wildfires in 2020 and 2021. In years of low fires, such as 2019, the offset reached as high as 31.5%.

The report, "Federal Lands Greenhouse Gas Emissions and Sequestration in the United States: Estimates for 2005-22" and data release are available online.