Additionally, it can be difficultto isolate environmental factors from other drivers of migration. In the Middle East and North Africa, for example, it has been predicted that environmental degradation will reduce the amount of fertile arable land and thus compound a shortage of employment for a youthful population expanding quickly as a result of demographic trends, a proportion of whom may thus migrate to look for work.131 In this case, environmental degradation, demographic trends and economic factors (a lack of employment) combine as potential drivers for migration. There is no agreed definition or defined category and no explicit legal or normative framework pertaining to people moving as a result of the effects of environmental change.