2.3.3—Carbon stores
- Syllabus
- First assessment 2026
- Objective
- 2.3.3
- Level
- SL
Classify Carbon Stores and Residence Time
A carbon store is a pool; residence time is how long carbon typically remains there before leaving.
Atmosphere, soil and ocean hold inorganic carbon forms; organisms and fossil fuels hold organic carbon in the guide’s classification. Residence time helps distinguish fast biological exchange from slow geological storage.
A leaf may exchange carbon within months, while carbon buried in fossil fuel can remain isolated for millions of years.
Atmosphere; limestone’s geological residence time is much longer.
A large store is not automatically a fast store; size and residence time are different properties.