2.3.7—Fossil fuels as carbon stores
- Syllabus
- First assessment 2026
- Objective
- 2.3.7
- Level
- SL
See How Fossil Carbon Becomes a Rapid Source
Burial can isolate ancient organic carbon for geological time; extraction and combustion move it to atmospheric CO₂ quickly.
A slow geological store becomes a rapid source when humans change the rate of release. The key contrast is residence time, not whether carbon is ‘natural’.
Coal formed from old plant material over long timescales, but burning a truckload releases its carbon in hours.
It transfers a long-isolated store into the atmosphere much faster than natural sinks usually remove it.
‘Natural origin’ does not mean a present-day release is balanced or harmless.