U.S. States Record Sharp Decline In Per Capita CO2 Emissions Since 2005 – EIA

Per capita carbon dioxide emissions from energy use have declined in every U.S. state between 2005 and 2023, according to newly released data in the State Energy Data System. Over this period, total energy-related CO2 emissions in the country fell by 20% while the population grew by 14%. This combination led to a 30% reduction in per capita CO2 emissions nationwide. The drop in emissions was mainly driven by a sharp decline in coal use for electricity generation, which was replaced by natural gas and renewable energy sources such as wind and solar. Natural gas emits about half as much CO2 per unit of energy as coal, while renewables emit none.

Despite the long-term decline, the U.S. Energy Information Administration’s Short-Term Energy Outlook projects that overall CO2 emissions in the country could increase slightly by about 1% in 2025. This rise is linked to higher fossil fuel use, particularly from crude oil production and growing electricity demand.

The state-level data include emissions from fossil fuel consumption across all sectors, such as electricity generation, transportation, industry, and residential use. Emissions from power plants are assigned to the state where the facilities are located, even if electricity is exported to other states or countries. Similarly, transportation emissions are counted in the state where fuels are sold, regardless of where vehicles, planes, or boats eventually travel.

Maryland stands out for achieving the steepest decline in per capita CO2 emissions, which fell by 49% between 2005 and 2023. During this time, the state’s total emissions dropped by 43%, while its population grew by 11%. In 2023, Maryland recorded the lowest per capita CO2 emissions of any state at 7.8 metric tons per person, the second-lowest figure in available historical data. The District of Columbia had even lower per capita emissions at 3.6 metric tons, tying its record low.

The change in Maryland’s emissions reflects a major transformation in its electricity generation mix. In 2005, coal made up 56% of its power production, while natural gas accounted for only 4%. By 2023, those shares had nearly reversed, with coal providing just 5% and natural gas 41%. Alongside new solar and wind generation, this shift resulted in a 74% decline in emissions from the state’s power sector. Similar patterns of coal plant retirements and replacements with gas and renewables drove emission reductions in other states as well.

Nationwide, the sources of emissions vary by sector. In 2023, transportation was the largest source of CO2 emissions in 28 states. In 14 of these, transportation overtook the power sector as the leading source since 2005 due to declining coal use and steady petroleum consumption. Transportation dominates emissions in most coastal states, which tend to be more densely populated, have high levels of road and air travel, and no longer rely on coal for electricity.

The electric power sector remained the leading source of emissions in 18 states, many of which generate large amounts of coal-based electricity for export. States such as West Virginia, Wyoming, Kentucky, Missouri, and North Dakota still rely on coal for over half of their electricity production. The industrial sector was the top source in four states, including Texas, Louisiana, Alaska, and Iowa, due to their large oil, gas, refining, manufacturing, and agriculture industries.

Nationally, the electric power sector was the top source of CO2 emissions until 2016, when transportation surpassed it. Both sectors peaked in 2007, but power sector emissions have since declined more rapidly thanks to the transition away from coal. Transportation emissions have been slower to fall because petroleum products remain the main fuel, despite growth in electric vehicle adoption and reduced demand during the COVID-19 pandemic.