What do you mean by global warming?

Explanation

**Step-by-Step Solution:**

1. **Definition of Global Warming**: Global warming refers to the long-term increase in Earth's average surface temperature.

2. **Causes of Global Warming**: This increase in temperature is primarily due to the rise in the concentration of greenhouse gases in the atmosphere.

3. **Greenhouse Gases**: Greenhouse gases include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and others. These gases trap heat from the sun in the Earth's atmosphere.

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