It's because CO2 is by far the largest contributor, accounting for 80% of warming emissions from human activities in the US: https://www.epa.gov/ghgemissions/o

It's because CO2 is by far the largest contributor, accounting for 80% of warming emissions from human activities in the US: https://www.epa.gov/ghgemissions/overview-greenhouse-gases https://www.epa.gov/ghgemissions/overview-greenhouse-gases Some gases containing sulfur and nitrogen are far more potent per molecule than CO2, but they are emitted in much smaller volumes. They collectively account for less than 10% of warming emissions.