Atmospheric radiation absorption and emission are dominated by the presence of all three phases of H 2 O. Like all molecules, CO 2 only absorbs and emits specific spectral wavelengths (14.77 microns) that constitute a tiny fraction of solar radiation energy in Earth's atmosphere. The first 50 ppm of CO2 absorbs about half of this tiny energy, each additional 50 ppm absorbs half of the remaining tiny fraction, so at the current 380 ppm there are almost no absorbable photons left. CO2 could triple to 1,000 ppm with no additional discernable absorptionemission. This is the Beer-Lambert Law: The intensity of radiation decreases exponentially as it passes through an absorbing medium.