4.2 The human causes of climate change

The natural greenhouse effect is Earth's way of keeping our planet warm enough to support life. It works a bit like a blanket:

• Sunlight comes in: The Sun sends light to Earth, which passes through our atmosphere.

• Earth absorbs sunlight: The ground absorbs some sunlight, warming up.

• Heat goes out: As the ground warms, it releases heat, or infrared radiation.

• Gases trap heat: Greenhouse gases in the atmosphere, like water vapour, carbon dioxide (CO2), methane (CH4), and nitrous oxides, trap some of this heat, preventing it from escaping into space.

• Earth stays warm: Thanks to these gases, the heat keeps our planet at a temperature that’s good for plants, animals, and us.

So, without the natural greenhouse effect, Earth would be too cold for us to live on. It's when we add extra greenhouse gases that we enhance this effect, leading to more warming than usual – and that’s what's contributing to climate change

Humans are enhancing the greenhouse effect by increasing the concentration of greenhouse gases in the atmosphere. Here’s how:

• Burning Fossil Fuels: When we burn coal, oil, and gas for energy, we release carbon dioxide (CO2). This is the main way we add extra CO2 to the air.

• Deforestation: Trees absorb CO2, but when we cut or burn them down, that CO2 goes back into the atmosphere instead of being stored in the trees.

• Agriculture: Farming activities, especially raising livestock like cows, produce methane (CH4), a potent greenhouse gas. Rice paddies and the use of fertilizers also release greenhouse gases.

• Waste Decomposition: Landfills full of our waste emit methane as organic matter breaks down without proper oxygen.

• Industrial Processes: Factories and production plants release various greenhouse gases, including CO2 and nitrous oxide (N2O).

These activities have ramped up the greenhouse effect, causing Earth to warm more than it would naturally. This extra warming is changing our climate, affecting weather patterns, ecosystems, and sea levels.

Misconception 1: The greenhouse effect is always harmful.

• Reality: The natural greenhouse effect is essential for life on Earth; it’s the human-enhanced effect that’s causing climate issues.

Misconception 2: Only CO2 contributes to the greenhouse effect.

• Reality: Multiple gases, including water vapour, methane, and nitrous oxides, contribute to the natural and enhanced greenhouse effect.