Carbon dioxide in Earth's atmosphere able to synthesize food directly from and water using energy from light. However, not all organisms that use light as a source of energy carry out photosynthesis, since "photoheterotrophs" use organic compounds, rather than , as a source of carbon. In plants, algae and cyanobacteria, photosynthesis releases oxygen. This is called "oxygenic photosynthesis". Although there are some differences between oxygenic photosynthesis in plants, algae, and cyanobacteria, the overall process is quite similar in these organisms. However, there are some types of bacteria that carry out anoxygenic photosynthesis, which consumes but does not release oxygen. Carbon dioxide is converted into sugars
Carbon dioxide from the burning of fossil fuels remains in the atmosphere and is not absorbed by vegetation and the oceans. While transparent to visible light, carbon dioxide is a greenhouse gas, absorbing and emitting infrared radiation at its two infrared-active vibrational frequencies (see the section "Structure and bonding" above). Light emission from the earth's surface is most intense in the infrared region between 200 and 2500 cm, as opposed to light emission from the much hotter sun which is most intense in the visible region. Absorption of infrared light at the vibrational frequencies of atmospheric carbon dioxide traps energy near the