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
Space-based measurements of carbon dioxide and errors in fitting signals to obtain X, space-based observations may also be compared with ground-based observations such as those from the TCCON. There have been other conceptual missions which have undergone initial evaluations but have not been chosen to become a part of space-based observing systems. These include: Space-based measurements of carbon dioxide Space-based measurements of carbon dioxide () are used to help answer questions about Earth's carbon cycle. There are a variety of active and planned instruments for measuring carbon dioxide in Earth's atmosphere from space. The first satellite mission designed to measure was the Interferometric Monitor for