Increases in atmospheric concentrations of carbon dioxide (CO2) and other long-lived greenhouse gases such as methane, nitrous oxide and ozone have strengthened their absorption and emission of infrared radiation, causing the rise in average global temperature since the mid-20th century. Carbon dioxide is of greatest concern because it exerts a larger overall warming influence than all of these other gases combined.[1]
As noted above, "Carbon dioxide is of greatest concern [of the various greenhouse gases] because it exerts a larger overall warming influence than all of these other gases combined."