széndioxidegyenértékben

Carbon dioxide, CO2, is a colorless, odorless gas and a simple oxide of carbon. It is a minor but central component of Earth’s atmosphere, playing a key role in the carbon cycle and climate system. CO2 forms naturally from respiration, volcanic outgassing, and the decay of organic matter, and it is released in large quantities by burning fossil fuels and cement production. The molecule is linear, consisting of O=C=O, and at room temperature it exists as a gas.

In the atmosphere, CO2 is a long‑lived greenhouse gas. Its concentration is measured in parts per million; recent values are around 420 ppm with a steady upward trend. Because it is heavier than many surrounding gases and highly soluble in water, it participates in ocean–atmosphere exchange and contributes to ocean acidification. CO2 has a global atmospheric lifetime spanning decades to centuries, ensuring that current emissions influence climate for many generations.

Natural processes balance CO2 through photosynthesis by plants and phytoplankton, respiration by organisms, and chemical exchange with the oceans. Human activities have raised atmospheric CO2 by about 50% since the preindustrial era, driving a warming influence on the climate. Mitigation efforts focus on reducing emissions, enhancing carbon sinks, and capturing CO2 from industrial sources.

Common uses include beverage carbonation, food processing, inerting of flammable atmospheres, fire suppression systems, and as a solvent or reactant in various industrial processes. In environmental management, CO2 is also considered in carbon capture and storage (CCS) initiatives aimed at reducing atmospheric concentrations and mitigating climate change.