Translations:Greenhouse gas emissions by the United States/12/en

Greenhouse gases vary in how long they remain in the atmosphere. Though methane and nitrous oxide are more potent greenhouse gasses than CO
2, CO
2 is longer-lived, remaining in the atmosphere for centuries. The average CO
2 concentration in 2024 was over 424 parts per million (ppm), and exceeded 427 ppm in February 2025—each more than 50% higher than its pre-industrial level. Annual US national CO
2 emissions were exceeded only by those of China, which has four times the US population. Regardless of where emissions occur, the emitted gases spread around the world. This anthropogenic (human-caused) increase in greenhouses gases has impacts on weather patterns, droughts, heat waves, wildfires, ocean acidification, sea level rise, glacial melting, average global temperatures, extinction of species, and so forth.