Reported emissions from the metals sector decreased significantly from 112 million metric tons (MMT) CO₂e in 2011 to 90 MMT CO₂e in 2019, a decrease of 20 percent. Reported emissions decreased steadily between 2011 and 2016, with the largest decrease occurring in 2015 (13%). Emissions have remained below 2014 levels in recent years.  Annual emissions from the metals sector were lowest in 2016 (88 MMT CO₂e) and increased in 2017 and 2018. Emissions then decreased in 2019, although 2019 emissions were 1.7 MMT CO₂e higher than 2016. 

Iron and steel production are responsible for approximately 80 percent of the reported emissions in the sector. Crude steel production is closely tied to economic conditions and can vary from year to year, with corresponding fluctuations in emissions. From 2011 to 2016, emissions from iron and steel production decreased. As shown in the table below, there was a decrease in production during this period due to restructuring of the industry, technological improvements, and increased scrap steel utilization, which resulted in a corresponding drop in emissions .[1] The number of reporters in the iron and steel subsector also decreased during this period from 129 facilities in 2011 to 123 facilities in 2017. In 2017 and 2018, however, the industry saw an uptick in both pig iron production and steel production, leading to a corresponding increase in emissions in 2018. Annual emissions increased by 1.3 MMT (01.8 percent) in 2017 and by 1.8 MMT (2.5 percent) in 2018, while the number of reporters remained steady at 123. In 2019, while pig iron production and steel production remained steady, CO₂e emissions decreased by 1.4 MMT (2 percent) and the number of reporters dropped to 122.

*United States Geological Service Mineral Commodity Summaries 2020, available at:  https://minerals.usgs.gov/minerals/pubs/commodity/iron_&_steel/

Other Metal Production. The other metal production facilities are those operating under NAICS codes beginning with 331 (primary metal manufacturing). This subsector accounts for about 10 percent of the total CO₂e emissions from the metals sector. Unlike the other subsectors, these facilities report only GHG emissions from stationary fuel combustion sources. Overall, emissions reported by this subsector have declined from 9.4 MMT CO₂e in 2011 to 9.1 MMT CO₂e in 2019, while the number of reporters has increased from 121 in 2011 to 133 in 2019. Emissions for this subsector increased between 2011 and 2014 by 13 percent (1.2 MMT CO₂e) from 9.4 MMT CO₂e to 10.6 MMT CO₂e. This increase was due to both an increase in the number of facilities reporting (8 more facilities reported in 2014 than in 2011) and an increase of 4,570 MMT CO₂e in the average annual emissions per facility. Beginning in 2015, the average annual emissions per facility declined from 82,170 MT CO₂e in 2014 to 68,421 MT CO₂e in 2019.

Aluminum Production. Aluminum production accounts for 4.4 percent of the total CO₂e emissions reported for the metals sector. Emissions in this subsector have decreased from a high of 7.3 MMT CO₂e in 2011 to a low of 2.7 MMT CO₂e in 2017. In 2018 and 2019, emissions steadily increased to 3.4 MMT CO₂e and 4.0 MMT CO₂e, respectively. The decrease in emissions from 2011 to 2017 was due to industry emission reduction efforts and lower aluminum production. [1] The increases in emissions reported in 2018 and 2019 are likely due to increased aluminum production due to improved market conditions for U.S. aluminum plants. After declining each year since 2012, primary aluminum production increased in 2018 and 2019 by 20 percent and 22 percent, respectively. [2]

Ferroalloy, Lead, Magnesium, and Zinc. Ferroalloy, lead, magnesium, and zinc production account for less than 4 percent of the total CO₂e emissions reported for the metals sector. The combined emissions reported for the ferroalloy, lead, magnesium, and zinc subsectors has decreased from 6.1 MMT CO₂e in 2011 to 4.3 MMT CO₂e in 2019. The largest reduction was in the magnesium production subsector, which decreased by 817,000 MT CO₂e (about 45 percent). This reduction in emissions for the ferroalloy, lead, magnesium, and zinc subsectors is partly due to industry emission reduction efforts and to an overall decrease in the number of reporters, which decreased from 38 in 2011 to 33 in 2019.

[1]  Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2018. U.S. Environmental Protection Agency. April 13, 2020. EPA 430-R-20-002. Available at: https://www.epa.gov/sites/production/files/2020-04/documents/us-ghg-inventory-2020-main-text.pdf

[2] U.S. Geological Survey, Annual Aluminum Mineral Commodity Summary, January 2020, Available at: https://pubs.usgs.gov/periodicals/mcs2020/mcs2020-aluminum.pdf.