IB Environmental systems and societies Topic 3.2C IUCN Revision Notes (SL/HL)

IB Environmental systems and societies Topic 3.2C IUCN Revision Notes (SL/HL) | RevisionDojo

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The IUCN Red List: Ranking Every Species by Its Risk of Extinction

Definition

IUCN

The International Union for Conservation of Nature (IUCN) is the global authority on the conservation status of species.

What the Red List Is and Why It Matters

The International Union for Conservation of Nature (IUCN) runs the Red List, the world's main record of how close each species is to extinction.
It gives conservation a scientific, standardised measure of extinction risk that every country can use.
Repeated assessments track biodiversity trends over time, so we can tell whether conservation is working.
A species' status is used to prioritise where limited conservation money and effort go.

Note

By 2023 the IUCN had assessed over 160,000 species.
This is still less than 5% of all described species, so the true scale of risk is underestimated.

How the IUCN Assesses Extinction Risk

Species are placed in a category using quantitative thresholds applied to five main criteria.
1. Population size: small populations have low genetic diversity and higher risk.
2. Rate of population decline: a fast fall in numbers signals urgent danger.
3. Geographic range and area of occupancy: a small or shrinking range raises risk.
4. Degree of fragmentation: populations split into isolated patches recover poorly.
5. Probability of extinction: modelled from the data above to estimate risk over a set time.

Example

The European eel (Anguilla anguilla) is Critically Endangered from habitat loss, pollution and dams that block its migration.

The Nine Red List Categories

Extinct (EX): no individuals remain anywhere on Earth.

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IB Environmental systems and societies 3.2C IUCN Notes

The IUCN Red List: Ranking Every Species by Its Risk of Extinction

What the Red List Is and Why It Matters

How the IUCN Assesses Extinction Risk

The Nine Red List Categories

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The IUCN Red List: Ranking Every Species by Its Risk of Extinction

What the Red List Is and Why It Matters

How the IUCN Assesses Extinction Risk

The Nine Red List Categories

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Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

IB Environmental systems and societies 3.2C IUCN Notes

Topic 1: Foundation 3 subtopics

Topic 2: Ecology5 subtopics

Topic 3: Conservation and biodiversity3 subtopics

Topic 4: Water4 subtopics

Topic 5: Land2 subtopics

Topic 6: Atmosphere and climate change4 subtopics

Topic 7: Natural resources3 subtopics

Topic 8: Human populations and urban systems3 subtopics

HL lenses 3 subtopics

The IUCN Red List: Ranking Every Species by Its Risk of Extinction

What the Red List Is and Why It Matters

How the IUCN Assesses Extinction Risk

The Nine Red List Categories

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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The IUCN Red List: Ranking Every Species by Its Risk of Extinction

What the Red List Is and Why It Matters

How the IUCN Assesses Extinction Risk

The Nine Red List Categories

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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