CO2 induced climatic change and spectral variations in the outgoing terrestrial infrared radiation

The published temperature changes produced in general circulation model simulations of CO₂ induced climate modification are used to compute the top of the atmosphere, clear sky outgoing infrared radiance changes expected for doubled CO₂. A significant wavenumber shift is produced, with less radiance emerging in the 500-800 cm¹(20.0-12.5 μm) CO₂ band and with more emerging in the 800-1200 cm¹ (12.5-8.3 μm) window. The effect varies greatly with latitude. The radiance shift in the 2300 cm¹ (4.3 μm) region is of the order of 10-30% for doubled CO₂. It is suggested that the 2300 cm¹ region be carefully monitored as an aid in detecting the climatic effects of increasing CO₂. The change in the wavenumber-integrated radiant exitance is at most a few %.