Drought is a period of abnormally dry weather that can last for weeks, months, or even years. It can occur anywhere in the world, but it is most common in arid and semi-arid regions.
There are two main causes of drought: natural causes and human causes.
Natural causes
- Climate change: Climate change is making droughts more frequent and severe. This is because climate change is causing the Earth’s atmosphere to warm, which leads to more evaporation and less precipitation.
- Ocean temperatures: Ocean temperatures can also play a role in drought. For example, when the El Niño weather pattern occurs, it can cause warmer-than-average sea surface temperatures in the Pacific Ocean. This can lead to below-average precipitation in the southwestern United States.
- Changes in atmospheric circulation: Changes in atmospheric circulation can also lead to drought. For example, when a high-pressure ridge stalls over a region, it can block precipitation from reaching the area.
Human causes
- Deforestation: Deforestation reduces the amount of water that is returned to the atmosphere through evapotranspiration. Evapotranspiration is the process by which plants release water vapor into the air through their leaves.
- Overgrazing: Overgrazing can damage vegetation and reduce the soil’s ability to absorb water.
- Poor water management: Poor water management practices, such as over-irrigation and water pollution, can also contribute to drought.
