The Keeling curve shows seasonal oscillations superimposed on a long-term increase. The seasonal saw-tooth is BEST explained by:
- A
Volcanic emissions
- Bcheck_circle
Northern Hemisphere terrestrial photosynthesis cycling on annual scale
- C
Ocean acidification
- D
Ice age cycles
Explanation
Most land plants are in the Northern Hemisphere; in NH summer, photosynthesis lowers CO2; in NH winter, respiration/decay raise it, producing the saw-tooth pattern.