Per-capita emissions have fallen by 2/5 in New Hampshire over the past 20 years, better than the national average, according to estimates from the federal Energy Information Agency. (The report is here) Our biggest source of emissions is transportation, as is the case in the entire Northeast, because of reductions in emissions from electricity generation.

From the report:

Per capita CO₂ emissions from primary energy consumption decreased in every state from 2005 to 2023, according to recently released data in our State Energy Data System. Total energy-related CO₂ emissions in the United States fell 20% over that time, and the population grew by 14%, leading to a 30% decrease in per capita CO₂ emissions.

CO₂ emissions across the country primarily declined because less coal was burned in the electric power sector. Increased electricity generation from natural gas, which releases about half as many CO₂ emissions per unit of energy when combusted as coal, and from non-CO₂-emitting wind and solar generation offset the decrease in coal generation. Looking ahead, our Short-Term Energy Outlook forecasts a slight 1% increase in U.S. total CO₂ emissions in 2025, in part because of more recent increased fossil fuel consumption for crude oil production and electricity generation growth.

Our state energy-related CO₂ data represent emissions from primary energy consumption of fossil fuels (petroleum, natural gas, and coal) for all sectors. We count CO₂ emissions released at power plants in the state where they are located, even if the electricity generated is sent across the grid for use in other states or countries. Similarly, we account for transportation CO₂ emissions in the state where fuels are sold to end users, even if the vehicles, boats, or planes later travel across state or international lines.