1. Types of Burning
Burning, also called combustion, occurs in many forms in our daily lives and in nature.
- Wildfires are large, uncontrolled fires that spread rapidly through forests, grasslands, and bushes. They are caused by lightning, heat, or human carelessness. Wildfires release enormous amounts of smoke and gases into the atmosphere.
- Combustion engines power cars, motorcycles, buses, and aeroplanes. These engines burn petrol or diesel fuel to produce energy for movement. As a result, they release harmful exhaust gases such as carbon dioxide and carbon monoxide into the air.
- Waste incineration is the burning of rubbish and waste materials. Factories and municipalities burn solid waste to reduce its volume. However, this process releases toxic gases, ash, and smoke into the environment.
- Industrial burning occurs in factories and power stations that burn coal, oil, and natural gas to produce electricity and heat.
- Domestic burning includes burning wood or coal for cooking and heating homes, especially in rural areas.
All of these types of burning release gases and particles that pollute the air and affect the environment.
2. Composition of Air and How Burning Changes It
Clean, fresh air is made up of several gases in specific proportions:
- Nitrogen makes up about 78% of the air. It is a relatively inactive gas and does not take part in burning.
- Oxygen makes up about 21% of the air. It is the gas that supports burning (combustion). Without oxygen, nothing can burn.
- Carbon dioxide is present in a very small amount, about 0.04% of the air. It is produced naturally by living organisms when they breathe.
- Other gases such as argon and water vapour make up the remaining small percentage.
When burning takes place, oxygen from the air is consumed and carbon dioxide is produced in large quantities. For example, when petrol burns in a car engine, it uses up oxygen and releases carbon dioxide, water vapour, and carbon monoxide. As more burning occurs — in factories, vehicles, and homes — the level of oxygen in local areas may decrease slightly while carbon dioxide levels rise significantly across the planet. This change in the composition of air is one of the most serious consequences of large-scale burning.
3. Greenhouse Gases and Climate Change
Some gases in the atmosphere act like a blanket around the Earth. These are called greenhouse gases. The most important greenhouse gases are:
- Carbon dioxide (CO₂) — released by burning fossil fuels, deforestation, and industrial processes.
- Methane (CH₄) — released from landfills, livestock, and natural gas leaks.
- Water vapour (H₂O) — the most abundant greenhouse gas, increased by warming oceans.
- Nitrous oxide (N₂O) — released from agricultural activities and burning.
Greenhouse gases trap heat from the Sun inside the Earth’s atmosphere. Under natural conditions, this is helpful — it keeps the Earth warm enough to support life. However, when the concentration of greenhouse gases increases due to excessive burning and industrial activity, too much heat is trapped. This causes the Earth’s average temperature to rise gradually. This process is called climate change or global warming.
The effects of climate change include:
- Rising sea levels due to melting polar ice caps
- More frequent and severe storms, floods, and droughts
- Disruption of ecosystems and loss of biodiversity
- Extreme heat waves affecting human health and agriculture
4. The Greenhouse Effect and Fossil Fuels
The greenhouse effect is the natural process by which the Earth’s atmosphere traps some of the Sun’s energy to keep the planet warm. Here is how it works:
- The Sun sends energy to the Earth in the form of sunlight.
- The Earth absorbs this energy and warms up.
- The Earth then releases this energy back as heat (infrared radiation).
- Greenhouse gases in the atmosphere absorb this heat and prevent it from escaping into space.
- This trapped heat warms the Earth’s surface.
This natural greenhouse effect is essential for life. Without it, the Earth would be too cold to support living organisms.
However, fossil fuels — coal, oil, and natural gas — are formed from the remains of ancient plants and animals buried underground for millions of years. When we burn fossil fuels in power stations, vehicles, and factories, we release large amounts of carbon dioxide that have been stored underground for millions of years. This dramatically increases the concentration of greenhouse gases in the atmosphere, making the greenhouse effect much stronger than it should be. As a result, the Earth heats up at an abnormally fast rate.
Key Terms to Remember
- Combustion — the process of burning
- Greenhouse gas — a gas that traps heat in the atmosphere
- Greenhouse effect — the warming of Earth due to trapped heat
- Fossil fuels — coal, oil, and natural gas formed from ancient organisms
- Climate change — long-term changes in global temperature and weather patterns
- Carbon dioxide (CO₂) — the main greenhouse gas released by burning