The emissions for the waste sector have decreased by 4.6 million metric tons (MMT) CO₂e (4.2 percent) between 2011 and 2019. Reported emissions for the waste sector consists of municipal solids waste (MSW) landfills, industrial landfills, solid waste combustion, and wastewater treatment. Total emissions from the waste sector decreased from 114.9 MMT CO₂e in 2011 to 110105.3 5 MMT CO₂e in 20192020 (approximately 8 percent). The decrease in emissions was is likely due to the significant reduction in the number of reporters. In 2019, there were 144 fewer facilities reporting than in 2011.notable drop in reporters (in 2020 there were 180 fewer reporters than in 2011), along with a drop in emissions from MSW landfills.

Over 80 percent of emissions from the waste Over 75 percent of the emissions in this sector come from municipal solid waste (MSW) landfills. Reported emissions from MSW landfills dropped decreased from 94 MMT CO₂e in 2011 to 91 86 MMT CO₂e in 2019, a decrease of 3 MMT CO₂e (3 2020 (approximately 8 percent). The decrease in emissions was driven by is due to a number of factors, including a reduction in the number of reporters (116 117 fewer MSW landfills reported in 2019 2020 than in 2011), and along with changes to the rule for calculating methane emissions from MSW landfills. Starting in reporting year 2013, MSW landfills are allowed to assume that a higher percentage of methane generated by the landfill is oxidized to CO₂ as it passes through the landfill soil cover, resulting in lower reported methane emissions. Landfills are provided two equations for calculating methane emissions and are given the choice of which results to report. Landfills choosing to report the lower of the two estimates is likely contributing to lower reported emissions. In 2020, annual reported waste disposal as well as annual emissions decreased by 5 percent and 4 percent, respectively. Since 2011, waste disposal had been slightly increasing year to year.

In addition to MSW landfills, emissions also decreased from the other waste subsectors. Emissions from industrial waste landfills decreased 12 percent between 2011 and 2020 while emissions from solid waste combustors decreased 7 percent during this time, and wastewater treatment facilities dropped 10 percent.Reported emissions for the sector were 1.7 MMT CO₂e (2 percent) higher in 2019 than 2018, despite a continuing decrease in the number of reporters (27 fewer facilities reported in 2019 than in 2018). Most of this increase in reported emissions is from MSW landfills, whose emissions were 3 MMT CO₂e (3.2 percent) more than reported in 2018. Emission decreases were reported for industrial landfills (2.4 percent) and solid waste combustion (8.6 percent) subsectors, while there was no substantial change in emissions for the wastewater treatment subsector. The increase in emissions from MSW landfills are likely due to increased economic growth in 2019.  

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