Briefly outline the role of oceans as a source of carbon dioxide.

Briefly outline the role of oceans as a store of carbon dioxide.

Explain what is meant by the term “oceanic conveyor belt”.

Suggest two reasons why the oceanic conveyor belt is important.

Evaluate the success of one named conservation policy for sustainable fishing.

Award [1] for each of the following, up to a maximum of [2]:

• oceans are a source of carbon dioxide, which can be transferred to the atmosphere
• carbon dioxide is released during submarine volcanic activity
• carbon dioxide can be brought up from the ocean depths
• respiration of marine organisms
• other valid points.

Do not allow fossil fuels as a source.

Award [1] for each of the following, up to a maximum of [2]:

• the ocean is the major/largest store/sink of CO2
• acts as a sink for some of the carbon dioxide that has passed through the food chain; stored in sediments
• credit other valid points about oceanic storage of carbon.

Do not allow fossil fuels as a store.

Award [1] for each of the following, up to a maximum of [2] 

• the oceanic conveyor belt (OCB), refers to part of the large-scale ocean circulation
• places/oceans/currents are linked by the OCB
• cause or a pattern of the OCB, eg density gradients or the process of wind driven surface currents.

Candidates may approach this question from the perspective of human importance and/or system importance.

In each case, award [1] for identifying a valid reason and a further [1] for development or exemplification.

Possibilities include:

• Moderation of climates [1], so the thermal growing season for agriculture is extended/tourist development [1].
• Important because it transfers global heat energy between latitudes [1]; if the circulation stopped it would cause significant climate change [1].
• The conveyer belt reduces temperature differences between oceans [1], therefore linking the oceans as a single global system [1].
• OCB brings nutrients to the surface [1], and this supports abundant marine life/fish [1].

Conservation policies, eg the EU’s Common Fisheries Policy (CFP), may refer to the total allowable catch, the harvesting of juvenile fish, limiting the number of vessels, checking of landings, limited access to fishing grounds.

Sustainable fishing is the maximum number/weight/amount of fish that can be caught in any one year without depleting the stock/population. A sustainable fishing policy allows a depleted stock to recover its size.

Good answers may evaluate critically what is meant by “successful” and the temporal and spatial scales this brings into consideration. Another approach might be to evaluate whether sustainable fish yields can cater for rising demand and changes in the distribution of fish.

At band D, expect some description of an identified conservation policy in relation to sustainable fishing.

At band E, expect either greater explanation of how an identified conservation policy tries to achieve sustainable fishing or a critical evaluation of the success of the policy.

At band F, expect both.