Greenhouse Gases and Climate Change

This lesson covers greenhouse gases, the greenhouse effect and climate change as required by the Edexcel GCSE Combined Science specification (1SC0). You need to understand which gases contribute to the greenhouse effect, how human activities are increasing their concentrations, and the potential consequences.

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What Is the Greenhouse Effect?

The greenhouse effect is a natural process that keeps the Earth warm enough to support life. Without it, the average surface temperature would be about −18 °C instead of the current +15 °C.

How It Works

1. Short-wavelength radiation (visible light and UV) from the Sun passes through the atmosphere and reaches the Earth's surface.
2. The Earth's surface absorbs this radiation and warms up.
3. The warm surface re-emits energy as long-wavelength infrared (IR) radiation.
4. Greenhouse gases in the atmosphere absorb some of this outgoing infrared radiation.
5. The absorbed energy is re-emitted in all directions — some back towards the Earth's surface.
6. This keeps the Earth warmer than it would otherwise be.