Climate change is primarily driven by human activities that increase greenhouse gases in the atmosphere, along with some natural factors. Here are the main reasons:

## **Human Causes (Primary Drivers)**

### **Greenhouse Gas Emissions**
- **Burning fossil fuels** (coal, oil, gas) for electricity, heat, and transportation releases CO₂
- **Deforestation** reduces Earth's capacity to absorb CO₂ and releases stored carbon
- **Industrial processes** emit CO₂, methane, and other greenhouse gases
- **Agriculture** produces methane (livestock) and nitrous oxide (fertilizers)

### **How Greenhouse Gases Cause Warming**
These gases trap heat in the atmosphere like a blanket, preventing it from escaping to space - a process called the greenhouse effect. While this occurs naturally, human activities have intensified it.

## **Natural Factors (Secondary)**

- **Solar variations** - Small changes in the sun's energy output
- **Volcanic eruptions** - Can temporarily cool climate by blocking sunlight
- **Ocean cycles** - Like El Niño and La Niña affect regional temperatures
- **Earth's orbital changes** - Occur over thousands of years

## **The Evidence**

Scientists know human activities are the main cause because:
- The warming matches the pattern expected from greenhouse gases
- Natural factors alone can't explain current warming
- CO₂ levels are the highest in over 3 million years
- The timing correlates with industrialization

While Earth's climate has always varied naturally, the current rapid warming is unprecedented and directly linked to human activities since the Industrial Revolution.
