which processes result in the release of carbon
For example humans and plants give off carbon dioxide through respiration, making them a source of carbon dioxide, while plants absorb carbon dioxide during photosynthesis, making them a sink. The ocean acts both as a source and a sink, releasing carbon dioxide and absorbing it through natural processes. Volcanic eruptions act as a natural source of CO2. However, the amount of carbon released through volcanic eruptions is relatively small. Human contributions.