IB ESS SL 2.3.9 Ocean Carbon Exchange Question Bank
Explain exchange of carbon dioxide between atmosphere and ocean and its controls.
- Syllabus
- First assessment 2026
- Course
- ESS SL
- Level
- SL
Explain exchange of carbon dioxide between atmosphere and ocean and its controls.

Figure Carbon cycle
Using the data in Figure, calculate the net gain in carbon in the oceans in 1015 g.
Complete correct answer:
Net gain in carbon in the oceans:
Inputs to oceans = 92 + 0.8 = 92.8 Pg
Outputs from oceans = 90 + 0.1 = 90.1 Pg
Net gain = 92.8 - 90.1 = 2.7 Pg
Since 1 Pg = 10^15 g, the net gain is 2.7 x 10^15 g.
Marking guidance:
Award 1 mark for 2.7 in units of 10^15 g, with valid use of the Figuredata.
Describe one advantage and one disadvantage of the oceans as a carbon sink.
Advantage:
Disadvantage:
Describe one advantage and one disadvantage of the oceans as a carbon sink.
Advantage:
oceans are large so absorb a lot of CO2 / increases primary productivity/photosynthesis / reduces global warming/climate change;
Disadvantage:
increasing CO2 in oceans causes acidification / ocean acidification harms sensitive marine species/ecosystems like coral reefs;