Extreme weather

1. Reasons

1.1. Greenhouse gases

1.2. Warm air

1.3. Unknown natural causes

2. Drought

2.1. Mediterranean Basin

2.2. Mexico

2.3. the southwestern United States

2.4. South Africa

2.5. southern Australia

2.6. Damper

2.6.1. Canada

2.6.2. Northern Europe

3. Rainy

3.1. More

3.1.1. Polar regions

3.1.2. Subpolar regions

3.2. Less

3.2.1. Subtropics area

4. Rain Problems

4.1. Quality

4.2. Quantity

5. Political problems

6. Affected civilizations

6.1. Anasazi civilization

6.2. Akkad empire

6.3. the Classic Maya civilization

6.4. the Old Kingdom of Egypt

6.5. the Tiwanacu civilization