The planet's energy resources
An energy resource is a source we use to make electricity, heat or fuel for vehicles.
- Non-renewable (fossil) resources: coal, oil and natural gas formed from dead plants and animals over millions of years. They will run out, and burning them releases carbon dioxide, which adds to global warming. Nuclear fuels like uranium are also limited.
- Renewable resources: the sun (solar), wind, flowing water (hydro), the heat inside the Earth (geothermal) and plant matter (biomass). They are naturally refilled and release little or no carbon dioxide while working.
Worldwide, about 8 in every 10 units of energy still come from fossil fuels, but the renewable share is growing every year.
Why biodiversity matters
Biodiversity is the variety of life: different species, the differences inside a species and different habitats such as forests, wetlands and coral reefs.
It matters because:
- Food webs stay joined, so one change does not collapse the ecosystem.
- Plants, insects and microbes give us food, pollination, clean water, fertile soil and medicines.
- A varied ecosystem recovers better from drought, disease and storms.
- Nature also has beauty and cultural value.
Biodiversity falls because of habitat loss, pollution, over-hunting and over-fishing, invasive species and climate change. Many of these are linked to how we use land and energy.
Sustainable development
Sustainable development means meeting the needs of people today without taking away the chance of future people to meet their own needs. It joins three parts: a healthy environment, a fair society and a strong economy.
What each of us can do: save electricity, use public transport or walk, reduce, reuse and recycle, protect trees and wild places, and support clean energy. Nations also agree on rules and goals, such as protecting forests and cutting carbon dioxide.
Key formulas and definitions
- Fossil fuels (coal, oil, gas): non-renewable, release CO₂
- Renewable: sun, wind, water, geothermal, biomass
- Biodiversity = variety of genes, species and habitats
- Sustainable development = needs of today + needs of tomorrow
Worked examples
1. Is natural gas a renewable resource? Why?
No. Natural gas formed over millions of years from dead organisms. We use it much faster than it forms, so it will run out. It also releases CO₂ when burned.
2. A pond is polluted and frogs and fish die. Name one way this reduces biodiversity and affects people.
Species are lost, so the food web is weaker: birds that eat fish and frogs lose food. People who fish or use the pond water also lose a resource.
3. A town replaces 2 of its 10 coal power units with solar farms. What share of its energy is now renewable (if each unit is equal)?
Each unit is 10%. Two solar units give 20% renewable and 80% from the rest.
Common mistakes
- Thinking "renewable" means "free of any harm". Dams and large solar farms can also affect habitats, so they need careful planning.
- Believing that one lost species does not matter because there are many others.
- Saying "sustainable" only means saving the environment. It also includes people and the economy.
- Confusing biodiversity with the number of animals. It is the variety of kinds of living things.