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3.2 Human impact on biodiversity

Syllabus
First assessment 2026
Topic
3.2
Level
HL

Objective notes

13 learning objectives
3.2.1Threats to biodiversity

• Direct: overharvesting, poaching, illegal pet trade

• Indirect: habitat loss, climate change, pollution, invasive alien species

3.2.2Multiple human impacts

• Most ecosystems subject to multiple impacts

• Effects amplified when combined

3.2.3Invasive alien species

• Reduce biodiversity through competition, predation, diseases/parasites

3.2.4IUCN Red List

• Global conservation status assessment

• Based on: population numbers, rate changes, breeding potential, geographic range, threats

• Status ranks: least concern (LC) to extinct (EX)

3.2.5Conservation status benefits

• Publicizes species vulnerability

• Allows selection of conservation priorities and management strategies

3.2.6Species case studies

• Extinct species due to human activity

• Critically endangered species

• Species improved by intervention

3.2.7Tragedy of the commons

• Overexploitation of shared natural resources

• Tension between individual self-interest and sustainable development

• Examples: fish stocks, ocean plastic pollution

3.2.8(HL)—Biodiversity hotspots

• Under threat from habitat destruction

• Significant loss risk, especially in tropical biomes

3.2.9(HL)—Key Biodiversity Areas (KBAs)

• Sites contributing to global biodiversity persistence

• Hold species at extinction risk or ecosystems at collapse risk

3.2.10(HL)—KBA conflicts

• Exploitation vs. sustainable development vs. conservation

• Example: palm oil plantations in Malaysia/Indonesia

3.2.11(HL)—Traditional indigenous land management

• Can be more sustainable

• Challenges: population growth, economic development, climate change, lack of support

3.2.12(HL)—Environmental justice in conservation

• Must be considered when addressing biodiversity loss

• Impacts on indigenous and marginalized communities

3.2.13(HL)—Biosphere integrity planetary boundary

• Species extinctions have crossed critical threshold

• Could lead to Earth system tipping point

ConceptIB ESS HL