Major Environmental Issues
Human activities place huge pressure on the natural environment. The main issues are interconnected — for example, deforestation causes climate change, which makes droughts worse, which reduces food security.
Air Pollution
- From burning fossil fuels (industry, transport), agriculture, and waste burning
- Primary pollutants: sulfur dioxide (SO₂), nitrogen oxides (NOₓ), particulate matter (PM2.5)
- Health impacts: respiratory diseases; 7 million people die each year from air pollution (WHO)
- Environmental impacts: acid rain, smog, damage to ecosystems
Water Pollution
- Sources: industrial discharge, agricultural run-off (fertilisers, pesticides), plastic waste, sewage
- Effects: kills freshwater and marine life; unsafe drinking water; disease (cholera, typhoid)
- Eutrophication: excess nutrients (nitrates, phosphates) cause algae to bloom → oxygen depletion → aquatic life dies
Over 8 million tonnes of plastic enter the oceans each year. Plastics break down into microplastics (particles less than 5 mm) that are eaten by marine animals — from plankton to whales — and enter food chains, including food eaten by humans.
Soil Degradation
- Overfarming, erosion, salinisation, and desertification have degraded over a third of the world's soils
- Loss of topsoil reduces agricultural productivity and threatens food security
Resource Depletion
- Non-renewable resources (fossil fuels, metal ores) are finite — once used, they are gone
- Water scarcity: over 2 billion people lack safe drinking water; aquifers (underground water stores) are being pumped faster than they recharge
- Overfishing: many marine fish stocks are at or below sustainable levels
Biodiversity Loss
- Habitat destruction (deforestation, urbanisation) is the main cause of species extinction
- Current extinction rates are estimated to be 100–1,000 times the natural background rate
- Loss of biodiversity reduces ecosystem resilience and stability
The planetary boundaries concept identifies nine Earth system processes (including climate change, biodiversity, freshwater use) within which humanity can safely operate. Scientists believe we have already crossed the safe boundary for at least four of these.
Solutions at Different Scales
| Scale | Examples |
|---|---|
| Individual | Reduce waste, recycle, choose sustainable products, eat less meat |
| National | Environmental laws, taxes on pollution, renewable energy investment, protected areas |
| Global | International agreements (Paris Agreement, biodiversity targets), sustainable development goals (SDGs) |
The UN Sustainable Development Goals (17 SDGs agreed in 2015) provide a global framework addressing poverty, health, education, climate, and biodiversity together. SDG 13 is "Climate Action"; SDG 15 is "Life on Land." They recognise that environmental and human development issues cannot be solved separately.
Real world: The Great Pacific Garbage Patch — ocean plastic crisis
The Great Pacific Garbage Patch is a rotating mass of marine debris in the North Pacific Ocean, roughly twice the size of Texas. It is not a solid mass of plastic bags — it is mostly microplastics: tiny fragments of degraded plastic that have been eaten by fish, seabirds, and marine mammals. Researchers found microplastics in the stomachs of over 90% of seabirds sampled globally. The patch was first documented in 1997 and has grown since. The Ocean Cleanup project has been attempting to remove plastic using a large floating barrier, but critics argue source-reduction (producing less plastic) is the only long-term solution.
Real world: Delhi — the world's most polluted capital
Delhi regularly tops global rankings for air pollution. In November and December, a combination of crop stubble burning from neighbouring states, cold still air trapping emissions, vehicle exhaust from 11 million registered vehicles, and industrial emissions creates a toxic smog. PM2.5 levels — fine particles that penetrate deep into lungs — regularly exceed safe WHO limits by 20 to 40 times. Schools close, flights are cancelled, and residents wear masks year-round. Breathing Delhi's air in winter has been estimated to be equivalent to smoking 10–15 cigarettes per day. The crisis shows how agricultural, industrial, transport, and atmospheric factors combine to create extreme environmental health crises.
Real world: Cape Town's Day Zero — water scarcity in a modern city
In 2018, Cape Town, South Africa, came within weeks of becoming the first major city in the modern world to run out of water — an event officials called "Day Zero." After three years of drought, reservoirs fell to 13.5% capacity. The city ordered residents to use no more than 50 litres per person per day (a European city uses around 150 litres). Emergency standpipes were prepared for distribution. The crisis was caused by a combination of climate-change-linked drought, growing population, ageing infrastructure, and poor water management. Day Zero was ultimately avoided through strict rationing — but climate scientists warn that such events will become more frequent.
Where do you see this in real life? Environmental issues are often visible in everyday life: smoggy days in cities, litter on beaches, news about water restrictions. What local environmental issues affect your area — air quality, river pollution, plastic waste? What actions are your local government, national government, or local businesses taking? Environmental issues work at every scale, from the litter you drop to the international agreements your country signs.