Key facts & rules

• Deforestation: reduces biodiversity, increases CO₂ (burning), increases soil erosion, affects water cycle.
• Greenhouse gases: CO₂, methane, water vapour. Absorb and re-emit infrared radiation → warm Earth.
• Eutrophication: excess fertiliser → algal bloom → algae die → bacteria decompose → bacteria use O₂ → aquatic animals die.
• Pesticides: may accumulate along food chain (bioaccumulation/biomagnification) — highest concentration in top predator.
• Conservation strategies: nature reserves, captive breeding, seed banks, international agreements.
• Sustainable development: meeting current needs without compromising future generations' ability to meet theirs.