The terms 'desert' and 'desertification' are subject to various interpretations due to the diverse components, processes and states they denote. Recognising 'land degradation' as a contested and perceptual term , this cross-chapter paper , defines land degradation as 'a negative trend in land condition, caused by direct or indirect human-induced processes including climate change, expressed as long-term reduction or loss of at least one of the following: biological productivity, ecological integrity or value to humans' . Desertification is land degradation in arid, semiarid and dry sub-humid areas . Following the above definitions, desertification is more common in arid and semiarid climates than in hyper-arid climates. When desertification does occur in arid and hyper-arid ecosystems it is often in oases and irrigated cultivated lands . Hyper-arid areas, except wetlands such as oases, wadis and riverbanks, are excluded in the United Nations Convention to Combat Desertification  definition of desertification used here, yet many of the world's deserts are in hyper-arid areas. Hyper-arid areas are therefore included when discussing deserts but not when discussing desertification. Deserts are not the end point in a desertification process . There is robust evidence of desertification in deserts, mostly driven by human activities and climate variability, expressed as loss of biological productivity, ecological integrity or value to humans to below their natural levels .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report