Introduction
A central theme in IB Environmental Systems and Societies (ESS) is the relationship between humans and ecosystems. The new syllabus, first assessed in 2026, places even greater emphasis on understanding how human actions alter ecological balance.
From deforestation to pollution, agriculture to urbanization, human activity drives change at both local and global scales. In ESS, you’ll study these impacts through a systems-thinking lens, looking at feedback loops, sustainability, and conservation strategies.
Quick Start Checklist: Human Impacts in ESS
- Deforestation and land use change disrupt biodiversity and nutrient cycles.
- Agriculture and food production affect soil, water, and energy flows.
- Pollution (air, water, soil) damages ecosystems and human health.
- Overexploitation (fishing, hunting, resource use) destabilizes populations.
- Climate change shifts species distributions and ecosystem stability.
- Tested through case studies, data analysis, and essay evaluation.
Major Human Impacts on Ecosystems
1. Deforestation
- Reduces carbon storage and contributes to climate change.
- Causes habitat loss and species extinction.
- Leads to soil erosion and reduced fertility.
2. Agriculture
- Intensive farming increases yields but depletes soils and adds chemical pollution.
- Irrigation affects freshwater systems.
- Livestock farming contributes to greenhouse gas emissions.
3. Pollution
- Air pollution (e.g., smog, acid rain) damages plants and soils.
- Water pollution causes eutrophication, harming aquatic life.
- Soil pollution from pesticides affects food webs.
4. Overexploitation
- Overfishing collapses marine food webs.
- Unsustainable logging damages forest ecosystems.
- Poaching and hunting drive species toward extinction.
5. Climate Change
- Alters temperature and rainfall patterns.
- Affects species migration, reproduction, and survival.
- Intensifies natural hazards, which ecosystems must adapt to.
Systems Thinking and Human Impacts
ESS teaches you to analyze human impacts not in isolation, but as interconnected processes. For example:
- Agriculture increases emissions → climate change alters rainfall → soil fertility declines → more deforestation for farmland.
This cycle shows how human impacts ripple across ecosystems.
How Human Impacts Are Tested
- Paper 1: Data-response questions may include graphs of deforestation rates, pollution levels, or population growth.
- Paper 2: Essay questions often require evaluating sustainability strategies and human impacts on ecosystems.
- IA: Many students investigate local human impacts, such as water pollution or urbanization effects on biodiversity.
Case Studies for Human Impacts
- Amazon Rainforest (Brazil): Large-scale deforestation for cattle ranching and soy.
- Great Barrier Reef (Australia): Coral bleaching due to climate change and pollution.
- Aral Sea (Central Asia): Water diversion for agriculture led to ecosystem collapse.
Using case studies in exams strengthens answers by showing real-world application.
Frequently Asked Questions (FAQs)
1. Do I need to know global and local examples of human impacts?
Yes. Examiners want to see both global-scale issues and local case studies. This shows you can apply systems thinking across different contexts.
2. How does ESS connect human impacts to sustainability?
The course emphasizes sustainable resource use, conservation strategies, and evaluating trade-offs in environmental management. Every human impact is linked to potential solutions.
3. How can I revise human impacts effectively?
Group impacts by theme (deforestation, pollution, agriculture) and pair each with at least one case study. RevisionDojo offers structured summaries that help you organize this efficiently.
Conclusion
Human impacts are at the heart of IB ESS 2026, making them one of the most important themes for exams and IAs. By understanding how human activities alter ecosystems—and linking them to sustainability strategies—you’ll develop the systems-thinking skills examiners look for.
Call to Action
Need exam-ready case studies and summaries of human impacts on ecosystems? RevisionDojo provides the best ESS resources, helping you connect human activities to ecological systems and ace your 2026 exams. Start revising smarter today!
