Greenhouse gases

The atmosphere

The atmosphere is a jacket of gases that surround our planet. It is made up of:

nitrogen (N) – 78.1%
oxygen (O) – 20.9%
argon (Ar) – 0.9%
carbon dioxide (CO₂) – 0.04%.

The rest is made of very small amounts of other gases, including water vapour.

Greenhouse gases and climate change

Greenhouse gases are gases from the Earth’s atmosphere that trap heat reflected from the Earth’s surface (like how heat is trapped in a greenhouse). We need some greenhouse gases to survive. Without them, the Earth would be -19°C, which is about the same temperature as your freezer!

In recent years, the amount of greenhouse gases in the atmosphere has increased so much that more heat is being trapped, causing an increase in the average temperature of the Earth (the planet is becoming warmer) and the global climate to change. The increase in the amount of greenhouse gases is caused by people and their actions. Human activities like burning fossil fuels (coal, oil and gas), deforestation and industrial processes release greenhouse gases into the atmosphere.

Several gases contribute to global warming:

Methane (CH₄) makes up 0.00018% of the atmosphere but is a very strong greenhouse gas. Methane is produced naturally by wetlands and by humans from landfills, agriculture and fossil fuels. In New Zealand, most methane is emitted from the digestive systems of ruminant livestock such as cattle and sheep.
Carbon dioxide from urban fossil fuel burning is responsible for 40% of Aotearoa’s gross carbon emissions.
Nitrous oxide (N₂O) is a potent and long-lived greenhouse gas. In New Zealand, most nitrous oxide is produced by micro-organisms acting on nitrogen introduced to the soil via livestock urine or synthetic fertilisers.
Fluorinated gases (F-gases) are manmade gases often used in coolants, foaming agents, fire extinguishers, solvents, pesticides and aerosol propellants. They are powerful greenhouse gases.

What is the difference between air pollutants and greenhouse gases?

We look at air pollutants and greenhouse gases differently because they affect the Earth in different ways.

Air pollutants can harm our health and environment. We measure air pollutants based on how much of these harmful substances are in the air and how they affect us in the short term, like causing breathing problems or making the air look dirty.

Greenhouse gases trap heat in the atmosphere, which causes the planet to warm up over time. We measure greenhouse gases by counting how much of these gases are in the air and assess how much heat they can hold and their long-term effect on the climate.