Whether people migrate or not, as a response to the adverse impacts of climate and environmental change, depends mainly on people’s perception of three factors: the need, the desire and the ability to migrate. When people do not feel the need or the desire to leave their home despite the problematic circumstances they are facing, immobility does not necessarily imply negative consequences, for instance when a community has enough resources to adapt in- situ. On the contrary, when people feel the need and the desire to migrate but do not have the possibility to do so, they can become “trapped” (Black et al., 2011) in hazardous circumstances. When individuals or communities face acute environmental stress (sudden-onset events) or slow-onset processes such as natural resource depletion, sea-level rise, land degradation, desertification, drought, reduced water availability and groundwater salinization and decreased crop yield among others which affect their livelihoods, migration can be one of the most efficient strategies to limit exposure to hazards and to reduce vulnerability and poverty by securing alternative livelihoods in safer and more economically viable areas. Yet, many people, particularly those already vulnerable due to existing economic, political or demographic factors, may be unable to migrate due to insufficient means, health or physical disabilities, absence of networks of support, social exclusion, limited political rights, conflict, or geographic isolation. In the absence of appropriate supportive policies and measures, these "trapped" communities (Black et al., 2011) become increasingly vulnerable with time, as the adverse impacts of environmental change continue to undermine their livelihoods.
Black, R. et al.
2011 Foresight: Migration and global environmental change, Final Project Report. The Government Office for Science, London.