Unsustainable resource use causes ecosystem collapse when extraction exceeds regeneration or waste inputs exceed the ecosystem's capacity to process them. This depletes storages, reduces resilience and can push the system across a tipping point into a less productive equilibrium.
Level: SL and HL: Subtopic 1.3 Sustainability
The Mechanism
An ecosystem contains storages, such as populations, soil nutrients and biomass, connected by flows. Sustainable use maintains these storages; unsustainable use causes long-term depletion.
| Stage | Effect on the ecosystem |
|---|---|
| Overexploitation | Harvesting exceeds natural replacement, so resource storages decrease. |
| Habitat and biodiversity loss | Smaller populations and damaged habitats reduce diversity. |
| Reduced resilience | Fewer species and smaller storages limit recovery from disturbance. |
| Positive feedback | Damage amplifies further damage, driving the system toward a tipping point. |
| Ecosystem collapse | The system shifts to a new equilibrium with altered functions and ecosystem services. |
The 1992 collapse of the northern cod fishery off Newfoundland, Canada, illustrates this process. Cod were removed faster than the population could reproduce, reducing the stock, disrupting the food web and removing natural income from fishing communities. Resulting unemployment shows that ecological collapse also has social and economic consequences.
A common misconception is that a renewable resource is automatically sustainable. It is sustainable only when use does not exceed regeneration and extraction, transport and processing avoid unacceptable ecological damage.
Unsustainable use can also create environmental injustice: communities dependent on fisheries, forests or freshwater may lose livelihoods and ecosystem services despite contributing least to overexploitation.
Exam Technique
For an explain question, give a linked causal chain: overuse reduces storages, biodiversity and resilience, which strengthens positive feedback and raises the risk of crossing a tipping point. Add a named example and precise systems terminology. A systems diagram should use boxes for storages and arrows for flows.