Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
Carbon dioxide (CO2) is a colorless gas with a density about 60% higher than that of dry air. It occurs naturally in Earth's atmosphere as a trace gas.
Related terms
Photosynthesis: This is the process used by plants to convert light energy into chemical energy that can later be released to fuel their activities. During this process, plants absorb CO2 from the atmosphere.
Greenhouse Gas: These are gases in Earth's atmosphere that trap heat. They let sunlight pass through the atmosphere but prevent Earth’s heat from escaping back into space. CO2 is one such gas contributing to global warming.
Respiration: This refers to processes within organisms where oxygen is delivered to cells and carbon dioxide removed; essentially breathing on cellular level.