Carbon capture is the removal of carbon from the earth's atmosphere for long-term storage, or sequestration. This can be done by removing carbon dioxide directly from the atmosphere and/or by trapping it at its emission sources before it enters the atmosphere. Carbon capture is extremely important because carbon dioxide is by far the most abundant greenhouse gas and because its rapidly increasing level in the atmosphere is the dominant cause of climate change.
Carbon capture occurs naturally through the growth of trees and other plants and also through absorption by the oceans. Although natural capture was formerly sufficient to keep the level of atmospheric carbon dioxide constant, it no longer is enough because of the huge and ever-increasing amount of burning of fossil fuels by humans together with massive deforestation worldwide. Although ocean absorption plays an important role, its capacity is limited, and it is resulting in ocean acidification.
Numerous industrial techniques have been developed for capturing carbon, both directly from emissions sources and from the atmosphere. However, all of them either remain at the experimental level or are only being deployed in small scale pilot facilities. Among the problems still confronting many of these technologies are high cost, low efficiency, and/or adverse environmental effects of the resources used in them. Because the increase in atmospheric carbon dioxide has been so massive, it is doubtful that such artificial carbon capture techniques will have a significant effect for a long time, if ever.