Fingerprint of CO2 and other gases on the greenhouse effect from direct satellite observation

We use 19 years of continuous near-global land and ocean direct AIRS satellite measurements combined with detailed atmospheric radiative transfer modelling to demonstrate strong strengthening in the greenhouse effect caused by CO₂ and detectable, but comparatively smaller strengthening, by CH₄ and N₂O. An increase in the outgoing longwave radiation is found in the 800-1000 cm⁻¹ atmospheric window resulting from the Planck response to surface heating. The combined use of satellite measurements and the radiative transfer model also demonstrate that reductions in concentrations of prohibited ozone depleting substances have weakened the greenhouse effect in the spectral region where these gases absorb thermal infrared radiation. The strong greenhouse effect strengthening signal in the satellite data in the spectral region 710-720 cm⁻¹ is a fingerprint of CO₂ increase since we demonstrate that other factors could not cause such a robust spectral feature. We show how the spectral clear sky instantaneous change in TOA flux relates to the greenhouse gas radiative forcing over the 19-year period.