What this lesson teaches
I can tell renewable from non-renewable resources and explain how reserves are classed and when supply runs out.
Syllabus 9173, Topic 1.1, 2. Environment and Resources. Will our supply of provisioning services ever be depleted?
Make a guess
Fish are a renewable resource. Can a fish stock still collapse?
- Not unless the fish are caught at once.
- No, because renewable resources do not run out.
- Yes, if catches keep exceeding breeding.
- No, because fish move to new seas.
Show the answer
Yes, if catches keep exceeding breeding.
Renewable means replaced within human timescales, not impossible to use up. Catching too many breeding fish cuts future breeding too.
Renewable means able to be replaced within human timescales, not impossible to use up.
Renewable resources are replaced by natural processes within timescales that matter to people. Fish breed, forests regrow and rivers are refilled by the water cycle. Each has its own rate and needs the right conditions. Sunlight and wind are renewable energy flows.
Non-renewable resources, like metal ores and fossil fuels, form so slowly that using them runs down a finite stock. Recycling metals reduces the need to mine more, but new ore does not form quickly. Burning fossil fuels changes them, so they cannot be reused.
Regenerative capacity is a resource's ability to replace itself. A renewable stock falls when use is faster than replacement. Catching too many breeding fish also cuts future breeding. Pollution or habitat loss can reduce regenerative capacity, so a once-safe harvest becomes too high.
Put these in order
A fishery catches more each year than the stock can replace. Put the chain in order.
- The stock collapses and the fishing industry loses its livelihood.
- The fish stock shrinks.
- Fewer young fish join the stock each year.
- Boats catch more fish each year than the stock replaces by breeding.
- Fewer breeding fish remain.
Show the answer
- Boats catch more fish each year than the stock replaces by breeding. When use is faster than replacement, the number of fish left in the sea falls.
- The fish stock shrinks. A smaller stock contains fewer adult fish that are old enough to breed.
- Fewer breeding fish remain. With fewer parents, fewer young fish are born to replace those caught.
- Fewer young fish join the stock each year. If catches stay high while renewal falls, the gap between use and replacement widens.
- The stock collapses and the fishing industry loses its livelihood.
Sunlight is a flow, not a breeding stock, so using it does not deplete it like overfishing. But solar panels still need materials and space. Management must compare use with regrowth, using catch limits, protected areas and monitoring.
- Renewable
- Replaced naturally within human timescales.
- Non-renewable
- Finite stock that forms far too slowly.
- Regenerative capacity
- A resource's ability to replace itself.
Step by step
Stock or flow?
What is replaced, and by what process?
Compare rates
Is use faster than replacement?
Check feedback
Does depletion cut future renewal?
Real examples to use
Aral Sea, Central Asia
Soviet schemes diverted its rivers to irrigate cotton. The sea lost about 90% of its area, destroying its fishing industry.
Grand Banks cod, Canada
Overfishing caused the cod stock to collapse. A fishing ban in 1992 put tens of thousands of people in Newfoundland out of work.
Worked example: A shrinking fish stock
In a made-up fishery, a stock starts at 100 units, grows by 20 and loses 30 to fishing. So 90 remain. Repeating this is risky, because a smaller breeding stock may grow more slowly.
Watch out for this
Catching less than the original stock is always sustainable.
Compare the catch with replacement over time, including any drop in future breeding.
Check your understanding
A forest regrows, but cutting keeps exceeding regrowth each year. Which statement is correct?
- The forest must be non-renewable because it is shrinking.
- The forest is renewable, but it is being depleted.
- Regrowth keeps the stock constant.
Show the answer
The forest is renewable, but it is being depleted.
Yes. Renewable resources can still run down.