Big picture: Cost-benefit analysis (CBA) is a systematic approach to comparing the total costs and benefits of a decision, including environmental and social factors.
- Cost-Benefit Analysis (CBA)
- A method of comparing the total expected costs against the total expected benefits of a project or decision.
- Discount rate
- The rate used to reduce future costs and benefits to their present value, reflecting the idea that money today is worth more than money in the future.
- Contingent valuation
- A method of estimating the value of environmental goods by asking people how much they would be willing to pay to protect them.
Challenges of environmental CBA
- How do you put a monetary value on a species or ecosystem?
- Discount rates undervalue future generations' wellbeing
- Some environmental damage is irreversible
- Cultural and spiritual values are hard to quantify
- Uncertainty about long-term environmental impacts
IB exam tip: When evaluating CBA, always discuss its usefulness AND its limitations — especially the difficulty of valuing ecosystem services.
Types of ecosystem service value
- Direct use value — timber, food, water, medicine
- Indirect use value — pollination, flood protection, carbon storage
- Option value — potential future uses (e.g., undiscovered medicines)
- Non-use value — knowing an ecosystem exists, even if never visited (existence value)
Key concept: Natural capital refers to the stock of natural resources and ecosystems that provide benefits (ecosystem services) to humans. Depleting natural capital reduces the ability to provide these services.
Methods of valuation
- Market pricing — value of goods traded (timber, fish)
- Replacement cost — what it would cost to replace a natural service artificially
- Travel cost method — how much people spend to visit natural areas
- Willingness to pay — surveys asking what people would pay to protect nature
Discount rate controversy (HL): High discount rates reduce the present value of future environmental damages, potentially undervaluing the wellbeing of future generations. This raises ethical concerns about intergenerational equity and whether current economic decisions unfairly prioritise short-term benefits.
CBA limitations in environmental decisions
- Irreversible damage cannot easily be priced
- Uncertainty about long-term ecological impacts
- Future generations may be undervalued through discounting
- Cultural and intrinsic values are difficult to monetise
IB exam tip: In evaluate questions, always discuss the ethical implications of discount rates and link cost-benefit analysis to intergenerational equity.
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Advantages of Valuation
- Makes environmental costs visible to policymakers
- Allows comparison of different policy options
- Can justify conservation spending
- Integrates environment into economic planning
Limitations of Valuation
- Reduces nature to monetary terms
- Ignores intrinsic value of ecosystems
- Cultural values cannot be monetised
- Valuations vary widely depending on methods
- Future impacts are discounted and undervalued
IB exam tip: Connect economic valuation to ethics — an ecocentric view would argue that nature has value beyond what economics can capture.