fleeing sweeping-operations mindanao 2009

What is forced migration?

There is no universally accepted definition of what constitutes forced migration, also sometimes referred to as forced or involuntary displacement. You will find below a number of definitions used by different organisations studying or monitoring the phenomenon and sometimes involved in assisting and protecting some categories of forced migrants.


The International Association for the Study of Forced Migration (IASFM) describes forced migration as « a general term that refers to the movements of refugees and internally displaced people (those displaced by conflicts) as well as people displaced by natural or environmental disasters, chemical or nuclear disasters, famine, or development projects. »

displaced mother and child in Zamboanga june 2014
Displaced mother and child displaced stranded in an IDP camp in Zamboanga, Philippines, June 2014

Another useful definition is provided by the International Organisation for Migration (IOM) where forced migration is defined as « a migratory movement in which an element of coercion exists, including threats to life and livelihood, whether arising from natural or man-made causes (e.g. movements of refugees and internally displaced persons as well as people displaced by natural or environmental disasters, chemical or nuclear disasters, famine, or development projects)« . This definition highlights the element of coercion and therefore the involuntary character of the migratory movement or displacement.

Within these general definitions, one could distinguish 3 broad categories of forced migrants.

Internally displaced persons (IDPs): according to the Guiding Principles on Internal Displacement IDPs are « persons or groups of persons who have been forced or obliged to flee or to leave their homes or places of habitual residence, in particular as a result of or in order to avoid the effects of armed conflict, situations of generalized violence, violations of human rights or natural or human-made disasters, and who have not crossed an internationally recognized state border. »  One should note that this definition is largely descriptive and does not confer a special legal status to IDPs. Since they remain in their country of origin, IDPs, as any other citizen, are entitled to enjoy the same fundamental rights as other citizen with national authorities ultimately responsible for their protection.

Refugees: since the 1951 Refugee Convention and its 1967 protocol signed by 145 States parties, a refugee is a person who « owing to well-founded fear of being persecuted for reasons of race, religion, nationality, membership of a particular social group or political opinion, is outside the country of his nationality and is unable or, owing to such fear, is unwilling to avail himself of the protection of that country« .

International migrants: while there is no legal definition, an international migrant is « someone who changes his or her country of usual residence, irrespective of the reason for migration or legal status« . This would include refugees, asylum seekers, economic migrants but also people leaving their countries in order to escape famine, hunger or a lack of livelihood opportunities.

Causes of displacement

The causes of displacement are multiple and often inter-related.

There are 3 broad causes of displacement which is often described or labelled on the basis of these 3 causes.

Conflict (or conflict-induced displacement): under this category we find people forced from their homes due armed conflict, including civil war; generalized violence or human rights violations, including persecution on the grounds of nationality, race, religion, political opinion or social group. People may flee to a safe area within the boundaries of their country, in which case they are IDPs, or they flee across an internationally recognised border, in which case they may become refugees.

Natural disasters (or disaster-induced displacement): here we would find people uprooted from their homes as a result of a result of natural disasters (floods, volcanoes, landslides, earthquakes), environmental change (deforestation, desertification, land degradation, global warming) and human-made disasters (industrial accidents, radioactivity). People who remain in their country would qualify as IDPs, however, those moving to another country would not be recognised as refugees, as the 1951 Refugee Convention did not include these causes in the refugee definition. In recent years, the terms « environmental migrant » or « environmental refugee » have gained momentum with « climate refugee » being a sub-category, i.e. those fleeing the effects of climate change and global warming.

Developments projects (or development-induced displacement and resettlement (DIDR): in this category we would find people forced from their homes as a result of development projects, such as the construction of dams, roads, ports, airports, irrigation schemes, urban development, conservation parks, deforestation or mining projects.


Because forced migrants are by definition on the move, it is very difficult to estimate their numbers. The most accurate statistics concern refugees. As of 2017, UNHCR, the UN agency mandated to protect and assist them, estimated that 22.5 million people were refugees.

The exact number of IDPs in the world is unknown. Available statistics put the number of people displaced by conflict and violence at 40.3 million as of 2017. However, this number does not include people displaced by natural disasters, climate-change or developments projects. The generally accepted number of forced migrants, or victims of forced displacement, is usually obtained by adding the number of refugees to the number of people displaced by conflict and violence. As seen from the table below the forced displacement has been at its highest in recent years.


The number of people displaced by natural disasters or developments projects is largely unknown but is likely to number in the tens of millions.

The number of international migrants was estimated at the end of 2017 at 258 million. This figure included refugees and asylum seekers, who represent roughly 10% of the total.