Drought and desertification are two processes that result in disastrous impacts on people and biodiversity. But what actually are they?

Desertification is predominantly a human-induced issue that refers to the degradation of land in the dryland areas of the world. Land that was once fertile becomes degraded, resulting in soil erosion, sterility and a loss of biodiversity. As a result of this, the land becomes useless to people, livestock and wildlife. The land therefore loses its cultural, economic and environmental value alongside its biological diversity.

Desertification is not the expansion of existing deserts, instead it is the transformation of productive and fertile land into a desert.

The causes of desertification can be split into land management and climate related causes. Land management causes include overgrazing, deforestation, poor agricultural practice, removal of vegetation and overexploitation. The land management causes usually exist because of population growth, poverty and economic growth. Climate related causes include climate change and drought.

According to the UNCCD, approximately one million square kilometres of productive land are degraded annually—equivalent to the size of Egypt. Desertification, land degradation, and drought may displace up to 135 million people by 2045.

Drought in contrast, is a lack of precipitation over a period of time that subsequently leads to a water shortage. Drought is a naturally occurring issue, which unsurprisingly, is exacerbated by climate change that allows for drier, longer and hotter periods without rainfall.

There are both natural and human causes of drought. Unusual weather patterns are the natural cause of drought, El Niño and La Niña are just two weather patterns that are associated as such. These patterns are caused by a change in the surface temperature on the Pacific Ocean and subsequently cause drought; La Niña typically brings wetter conditions to Southeast Asia and Australia, while El Niño is more likely to cause droughts in those regions. In contrast, La Niña can lead to droughts in parts of East Africa and Southwest Asia. Of course, these processes are worsened by climate change but are a natural phenomenon.

Human causes of drought include climate change, deforestation and increased water usage. Climate change brings global warming, which exposes places to warmer than normal temperatures for longer periods which can result in a drought. Deforestation is a cause because forests are contributors to rainfall and without these forests reduce the clouds that form to bring rainfall. Finally, increased water usage causes and worsens droughts, for example, dams prevent the natural flow of water and can severely impact regions downstream when the flow of water is restricted.

Importantly, classifying a drought depends on the location. For example, some places are drier than others under normal circumstances, there is no set limit for what classifies as a drought and it is entirely dependent on the ‘normal’ or ‘average’ circumstances.