To what extent are the concepts of net productivity, natural capital and natural income useful models in managing the sustainable exploitation of natural resources? [9 marks]

Indicative Content	Guidance
Understanding key concepts: Define and explain concepts of net productivity / natural capital / natural income Demonstrate familiarity with related terms → e.g. stock sustainability / replenishment / maximum sustainable yield / rates of harvest / renewable/non-renewable resources Linking to sustainability: Discuss how concepts of net productivity / natural income link to sustainable harvesting practices Explore how these concepts apply to abiotic/biotic resources / renewable/non-renewable resources / goods/services Examples of resource management: Provide specific examples of net productivity / natural income for named resources → e.g. timber / freshwater / fish populations / fossil fuels Highlight impacts of unsustainable extraction → e.g. bycatch in fisheries Balanced analysis: Analyse extent to which net productivity / natural income are effective models for ensuring sustainable resource use Consider limitations / factors not addressed by these concepts	You will always have to answer two 9 mark questions from Section B in your IB ESS SL Paper 2 exam This is a 'level of response' answer. The examiner will award you a combined mark out of 9 for knowledge, application, analysis and evaluation ‘To what extent’ (for 9 marks) requires: Knowledge of concepts, principles and models Application to the context using relevant and focused examples Analysis showing logical and coherent chains of reasoning of a range of issues Evaluation showing critical thinking linked to the context Depth is more important than breadth It is sensible to discuss two or three main points but to apply, analyse and evaluate them fully For top-level evaluation, informed judgement is required This can be demonstrated in a conclusion that synthesises and weighs up the arguments to form a supported answer to the question
Model Answer
Managing the sustainable exploitation of natural resources requires a clear understanding of certain key concepts, such as net productivity, natural capital, and natural income. Net productivity, representing the gain in biomass through growth and reproduction, can mainly be applied to biotic (living) resources [K]. Natural capital refers to the sum of natural resources in a given environment and natural income refers to the growth or 'interest' on that capital over time [K]. A resource can be sustainable when its long-term yield is not negatively affected by short-term harvesting [K]. For example, overfishing in the North Sea or the Grand Banks of Newfoundland led to serious declines in fish stocks, demonstrating the importance of sustainable yield calculations [Ap]. Sustainable harvesting should not exceed the natural income generated by the resource, ensuring that the natural capital remains available for future exploitation. However, both net productivity and natural income have limitations. Net productivity focuses primarily on biotic resources, such as fisheries and forests, and doesn't consider potential environmental damage during extraction, like habitat destruction [Ap]. Similarly, natural income, whilst providing a way to estimate maximum sustainable yields, may not take into account other negative effects of resource extraction processes [An]. For example, deforestation for timber extraction may lead to habitat loss, soil degradation, and disruptions in ecosystem services, which could have unforeseen consequences for forest growth in the future [Ap]. To manage resources sustainably, it is important to consider the broader context, including the impacts of extraction, transportation, and processing [An]. Policies and campaigns that alter human resource consumption behaviour and values play a crucial role in reducing unsustainable exploitation. In addition, emphasising the non-renewable nature of certain resources can make people more aware of the irreplaceable losses associated with their consumption [An]. In conclusion, whilst net productivity and natural income are valuable concepts for managing the sustainable exploitation of natural resources, a holistic approach considering the entire resource lifecycle is necessary for effective sustainable resource management [E].
Commentary
This answer is an example - yours may be different The answer discusses the benefits of these various concepts, as well as some limitations Their usefulness is clearly evaluated and a clear supported final judgement is given The response is annotated to show where the skills of knowledge (K), application (Ap), analysis (An) and evaluation (E) have been demonstrated

Resource Use in Society (SL IB Environmental Systems & Societies (ESS))

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