The IUCN Red List at HL: The IUCN Red List works the same for SL and HL. You'll use it again at HL when studying biodiversity hotspots and the scale of human impact on species.
No HL-only material to add — just learn how the Red List classifies species.
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Protecting species: the big picture
Big idea: Conservation status shows how likely a species is to become extinct and helps decide how urgently it needs protection.
What is conservation status?
Conservation status tells us whether a species is safe, under threat, or already extinct. It helps scientists and governments understand which species need the most help.
Conservation status = how close a species is to extinction.
Who decides conservation status?
Species are assessed globally by the International Union for Conservation of Nature (IUCN). The results are published in the IUCN Red List, which is used worldwide.
- Used by scientists and conservationists
- Used by governments and policymakers
- Helps set conservation priorities
How is conservation status decided?
The IUCN looks at several factors to judge how at risk a species is.
- Number of individuals left
- Whether the population is increasing or decreasing
- How easily the species can reproduce
- How wide its geographic range is
- Known threats such as hunting or habitat loss
In exams, mention population size, trend, range, and threats.
Understanding IUCN Red List categories
Species are placed into categories based on how serious the risk of extinction is.
- Least Concern (LC): widespread and common
- Near Threatened (NT): may become threatened soon
- Vulnerable (VU): high risk of extinction
- Endangered (EN): very high risk
- Critically Endangered (CR): extremely high risk
- Extinct in the Wild (EW): only survives in captivity
- Extinct (EX): no individuals remain alive
The higher the category, the greater the extinction risk.
Why conservation status is important
Giving a species a conservation status makes its situation public and encourages action to protect it.
- Raises awareness of threatened species
- Guides conservation funding
- Helps decide protection laws
- Supports long-term biodiversity protection
How governments help protect species
Governments play a major role in conservation by creating and enforcing rules.
- Passing laws to protect species and habitats
- Funding conservation and research
- Enforcing hunting and trade restrictions
- Working with other countries through agreements
How businesses affect conservation
Businesses can harm biodiversity, but they can also help protect it.
- Using sustainable materials
- Reducing pollution and waste
- Supporting conservation projects
- Developing technology to monitor wildlife
The role of NGOs
Non-governmental organisations (NGOs) support conservation by working directly with species, ecosystems, and communities.
- Funding conservation work
- Researching and monitoring species
- Raising public awareness
- Campaigning for better protection
What individuals can do
Individual actions may seem small, but together they make a big difference.
- Choosing sustainable products
- Reducing consumption
- Supporting conservation organisations
- Taking part in citizen science projects
Three real outcomes of conservation
- Some species go extinct when protection comes too late
- Some species remain critically endangered but survive with help
- Some species recover successfully with strong conservation action
Big exam takeaways
- Conservation status shows extinction risk
- The IUCN Red List is the global system
- Status is based on population, range, trends, and threats
- Governments, businesses, NGOs, and individuals all matter
- Early conservation action is most effective
Practice with real exam questions
Answer exam-style questions and get AI feedback that shows you exactly what examiners want to see in a full-marks response.
IB-style question — IUCN criterion — why classified Endangered
The Irrawaddy river dolphin (Orcaella brevirostris) was reclassified from Vulnerable to Endangered on the IUCN Red List between 2000 and 2017. Identify one IUCN criterion that could explain this reclassification. [1]
How to answer it, step by step
- Choose a directional criterion
• Population size decreased by >50% over three generations — meets IUCN Criterion A threshold for Endangered.
• OR: extent of occurrence (geographic range) reduced and fragmented by river dams. - Link it to the higher category
• A >50% decline or severely fragmented small sub-populations each face higher extinction probability → pushes species from VU to EN.
Final answer
Use a directional/comparative word — 'decreased population size', NOT just 'population size'. Threats (hunting, dams) are causes, not IUCN criteria — never state them as the criterion.
IB-style question — Data-deficient category — why status unknown
A large proportion of deep-sea fish species appear in the 'Data Deficient' category of the IUCN Red List. Explain one reason why a reliable conservation status cannot be assigned to these species. [1]
How to answer it, step by step
- Name the barrier + link to lack of data
• Deep-sea environments are too expensive and difficult to survey — standard trawl/dive methods can't reach depths below ~200 m.
• Without population-size or range data, none of the quantitative IUCN criteria (A–E) can be applied.
Final answer
One well-explained reason earns the mark — link the practical difficulty directly to the absence of data, not just 'we don't know about deep-sea fish'.