Desertification

Desertification is the persistent degradation of dryland ecosystems caused by variations in climate and human activities. Drylands occupy nearly half the planet's land area, and in 2000 were home to around one-third of the Earth’s population.

Drylands are, as the name suggests, areas where water is scarce. In the past, nomadic lifestyles and low levels of agriculture meant that the risk of over cultivation was relatively low. But the marginal conditions in drylands mean that climate change and human pressures can easily tip the balance and destroy their fragile ecosystems, leaving nothing but bare soils behind. Up to 20% of the world’s drylands have already been degraded, but the facts are that these changes are affecting the world’s poorest populations.

That these populations are the poorest, means that they rely on the local ecosystem more than the inhabitants of developed nations. Food, fuel, construction materials, grazing for livestock - all come from the local environment. As the climate fluctuates the desert expands, forcing people to cultivate further marginal land and leading to more land degradation.

A great case study to learn for use in essays and exams is that of the Masai tribes of the Kenyan Serengeti. Originally nomadic farmers, their traditional system of moving from one area to another allowed the land to recover, before commercial farmers moved in to convert the premium lands to commercial agriculture. When the Serengeti National Park was created the Masai and their herds were excluded. These two factors, along with expanding populations, forced the Masai on to marginal lands. Private ownership of land now limits the Masai’s ability to move, and so leads to overgrazing on these marginal lands. This overgrazing has lead to desertification.