# Human Impact on the Environment
Human population growth and increased resource use have significant impacts on the environment. Understanding these impacts and sustainable solutions is essential for GCSE Biology.
1. Population Growth
Human population has grown exponentially due to:
- Better medicine and healthcare
- Improved food production
- Better sanitation and clean water
More people → more resources needed → greater environmental impact.
2. Pollution
| Type | Cause | Effect |
|---|---|---|
| Water | Sewage, fertilisers, chemicals | Eutrophication, toxic to organisms |
| Air | Burning fossil fuels, factories | Acid rain, global warming, smog |
| Land | Landfill, pesticides, nuclear waste | Soil contamination, kills organisms |
Eutrophication
- Excess fertiliser washes into water (run-off)
- Algal bloom — algae grow rapidly on the surface
- Algae block light → plants beneath die
- Bacteria decompose dead plants → use up oxygen
- Other organisms die from lack of oxygen
3. Deforestation
Clearing forests for: farming, cattle, timber, biofuels, roads.
Effects:
- Loss of biodiversity (habitats destroyed)
- Increased CO₂ (trees no longer absorb it; burning releases it)
- Soil erosion
- Loss of potential medicines
- Disruption of water cycle
4. Global Warming
Greenhouse effect: CO₂, methane, water vapour trap heat in the atmosphere.
Human activities increasing greenhouse gases:
- Burning fossil fuels (CO₂)
- Deforestation (less CO₂ absorbed)
- Rice paddies and cattle (methane)
- Landfill sites (methane)
Consequences
- Rising sea levels (ice melting)
- Extreme weather events
- Species extinction (can't adapt fast enough)
- Crop failure in some regions
- Coral bleaching
5. Sustainability
Using resources in a way that meets current needs without compromising future generations.
Solutions
- Renewable energy (solar, wind, hydroelectric)
- Recycling and reducing waste
- Sustainable farming practices
- Reforestation
- International agreements (Paris Agreement)
- Reducing carbon footprint
6. Trophic Levels and Food Security
- Energy lost at each trophic level (respiration, heat, waste)
- Only ~10% energy transferred between levels
- Eating less meat reduces demand on land and resources
- Food security challenges: climate change, population growth, cost, pests
7. Practice Questions
- Describe the process of eutrophication.
- Explain three effects of deforestation.
- How do human activities contribute to global warming?
- What is sustainability? Give two examples.
- Why is less energy available at higher trophic levels?
Want to check your answers and get step-by-step solutions?
Summary
- Population growth → more pollution, deforestation, resource use
- Pollution: water (eutrophication), air (greenhouse gases), land
- Deforestation: less CO₂ absorbed, biodiversity loss
- Global warming: greenhouse gases trap heat → rising seas, extreme weather
- Sustainability: renewable energy, recycling, reforestation