**5. Desertification and food security**

The most critical role of the agricultural sector is to ensure sustainable food security. So food security is, by definition, a situation where everyone has access to adequate, healthy, and nutritious food [31]. Therefore, desertification can be considered one of the most important factors limiting agricultural product production and, ultimately, the challenge of food security. According to **Figure 6**, if the population grows at a fixed exponential rate, the amount of food required will increase exponentially. But Malthus held that the output of food could increase only by a constant amount each period. Given these two different growth processes, food requirements would eventually catch up with food production. The population hits the subsistence level of food production at the Malthusian trap, shown here at point T [32].

Drought stress in arid and semi-arid regions such as Iran has posed a serious challenge to sustainable production to provide food for the growing population. Concerns about the vulnerability of agricultural production become more pronounced when there is a proper understanding of the impact of climate change. If desertification leads to degradation and degradation of water, soil, and vegetation resources as three factors of survival in vulnerable ecosystems, food security will face serious problems. Thelma [33] reported that desertification has exacerbated the problem of food security in eleven states in northern Nigeria and its effect is very glaring on the agricultural sector.

**Figure 6.** *The Malthusian growth model [32].*
