CO2eq emissions absorb energy, trapping it in the atmosphere and reflecting it back as heat. The increased GHG levels and higher temperature cannot be sustained by the Earth’s natural environmental processes and are among the causes affecting the climate. These effects are demonstrated in more frequent, extreme temperature fluctuations and weather events, such as hurricanes, cyclones, tsunamis, severe storms, wildfires, droughts, and floods. Shifting patterns also result in record heat waves in formerly cold climates, and snow and hail in formerly warm climate zones. These changes have caused costly damage to critical infrastructure; disrupted food, water, and economic supply chains, and put people’s health, safety, security, and lives at risk.
According to the U.S. Environmental Protection Agency (EPA), total GHG emissions in 2021 accounted for 6,340 million tonnes (6,989 million tons), which is nearly 14 quadrillion pounds of CO2eq. The largest sources of GHGs emissions in the U.S. come from:
- Transportation sources. More than 94 percent
of the various modes of transportation use petroleum-based fuel. - Electric power. Approximately 79 percent of electricity generation uses fossil fuels, and the residential and commercial sector use 30 percent electricity, making it the largest end-user.
- Industrial. These emissions are mostly from burning fossil fuels for energy, as well as GHG emissions from certain chemical reactions necessary to produce goods from raw materials.
- Commercial and residential. These emissions are mostly from heating sources using fossil fuel, the use of certain products that contain GHGs, and the handling of waste.1
The internationally recognized Reporting Standard by Greenhouse Gas Protocol categorizes emissions reporting into three “scopes.”
- Scope 1: Direct emissions associated with the consumption of fuel, including transportation, equipment operation, and facility operation.
- Scope 2: Indirect emissions associated with purchased energy for electricity, steam, heating, and cooling.
- Scope 3: Indirect emissions for activities not included in Scope 1 or 2 that are listed in 15 categories, including waste generated in operations and end-of-life treatment of sold products.2
