Environmental change and disasters have always been major drivers of migration. However, climate change predictions for the 21st century indicate that even more people are expected to be on the move as extreme weather-related events, such as floods, droughts and storms become more frequent and intense (IPCC, 2014), and changes in precipitation and temperature patterns  impact livelihoods and human security.

The 2018 Global Compact for Safe, Orderly and Regular Migration (GCM), the first-ever negotiated global framework on migration, recognizes that migration in the context of disasters, climate change, and environmental degradation is a reality, and makes commitments to support both migrants and States.

No legal definition for persons on the move due to environmental drivers exists to date and neither an internationally accepted one. However, many actors work on these links, including IOM, and have developed conceptual frameworks to work with. IOM put forward in 2007 a broad working definition for Environmental Migration, which seeks to capture the complexity of the issues at stake.

“Environmental migrants are persons or groups of persons who, predominantly for reasons of sudden or progressive change in the environment that adversely affects their lives or living conditions, are obliged to leave their habitual homes, or choose to do so, either temporarily or permanently, and who move either within their country or abroad” (IOM, 2007:33).

This definition is deliberately broad and flexible in order to account for the diverse range of population movements due to all types of environmental drivers. This definition shows that environmental migration can take many complex forms: forced and voluntary, temporary and permanent, internal and international, individual and collective, of proximity and of long distance. The nature, duration and scale of environmental migration also depends on whether it takes place in the context of slow-onset events and processes (sea level rise, increasing temperatures, land degradation, etc) or sudden-onset events and processes (floods, cyclones, storms, etc.) that are exacerbated by the adverse effects of climate change and environmental degradation. It also depends to what extent it interacts with other socio-economic, cultural and political factors that influence the decision or necessity to move. Because of this complexity and multicausality, environmental migration should not be understood as a wholly negative or positive outcome – migration can amplify existing vulnerabilities, but it can also allow people to build resilience.

In the absence of a legal definition or an internationally accepted one, several other proposals were  made on categorizing the movements of people due to environmental drivers. They usually propose a narrower definition by either focusing on one type of movement (for instance displacement) or one type of environmental driver (for instance climate change impacts).

Climate migration refers to “the movement of a person or groups of persons who, predominantly for reasons of sudden or progressive change in the environment due to climate change, are obliged to leave their habitual place of residence, or choose to do so, either temporarily or permanently, within a State or across an international border” (IOM, 2019). Climate migration is thus a subcategory of environmental migration; it defines a singular type of environmental migration, where the change in the environment is due to climate change. While, this is an IOM working definition with an analytic and advocacy purpose which does not have any specific legal value, the term is used in the legally-binding Cancun Agreements on climate change adaptation, adopted by States Parties to the UN Framework Convention on Climate Change (UNFCCC) at the 2010 Conference. The Cancun Agreements identify three forms of “climate change induced” movement: displacement, migration, and planned relocation. The term has also been employed by the World Bank in projecting future movements due to the adverse impacts of climate change.

Planned relocation “in the context of disasters or environmental degradation, including when due to the effects of climate change, [refers to] a planned process in which persons or groups of persons move or are assisted to move away from their homes or place of temporary residence, are settled in a new location, and provided with the conditions for rebuilding their lives. The term is generally used to identify relocations that are carried out within national borders under the authority of the State and denotes a long process that lasts until “relocated persons are incorporated into all aspects of life in the new setting and no longer have needs or vulnerabilities stemming from the Planned Relocation”” (IOM, 2019; Georgetown University, UNHCR, and IOM, 2017; UNHCR, the Brookings Institution and Georgetown, 2015).

Disaster displacement is a term that “refers to situations where people are forced to leave their homes or places of habitual residence as a result of a disaster or in order to avoid the impact of an immediate and foreseeable natural hazard. Such displacement results from the fact that affected persons are (i) exposed to (ii) a natural hazard in a situation where (iii) they are too vulnerable and lack the resilience to withstand the impacts of that hazard” (Nansen Initiative, 2015). This term is mostly used to identify forced movements of people triggered by sudden-onset events in the environment. The concept of “cross-border disaster-displacement” is also sometimes associated with this term, particularly identifying the destination of population movements, to another country. “Disaster displacement” is used and promoted in the work of the Platform on Disaster Displacement as an umbrella term, while humanitarian agencies like IOM and UNHCR employ it with the narrow scope of forced sudden movements. The term is also used by the Internal Displacement Monitoring Centre (IDMC) in presenting annual estimates on new internal displacements in the context of disasters.

Human mobility is “a generic term covering all the different forms of movements of persons. The term human mobility reflects a wider range of movements of persons than the term “migration”. The term is usually understood as also encompassing tourists that are generally considered as not engaging in migration” (IOM, 2019). In the context of environmental drivers, human mobility is being used within the work of UNFCCC, where the Executive Committee of the Warsaw International Mechanism on Loss and Damage associated with climate change has a strategic workstream (d) dedicated to human mobility, and where the several international organizations have created the “Advisory Group on Climate Change and Human Mobility.” In this context, human mobility is understood as encompassing the three forms of “climate change induced” movement from the Cancun Agreement, namely, displacement, migration, and planned relocation. The term is increasingly used in multi-stakeholder engagements, as actors working on the different types of movements of people can easily converge towards it.

Climate refugee or environmental refugee are terms frequently used on purpose in the media and by activists to draw attention on the situation and needs of those uprooted because of disasters, climate change and environmental degradation. While their situations and needs can be similar to those of refugees, such as crossing a border after a disaster and needing protection and assistance, people moving for environmental reasons, do not fall squarely within any one particular category provided by the existing international legal framework. Terms such as "climate change refugee" or "environmental refugee" have thus no legal basis in international refugee law. There is also a growing consensus among concerned agencies, including IOM and UNHCR, that their use is to be avoided. These terms are misleading and fail to recognize a number of key aspects that define population movements in the context of climate change and environmental degradation, including that environmental migration is mainly internal and not necessarily forced, and the use of such terms could potentially undermine the international legal regime for the protection of refugees. In addition, all persons moving in the context of environmental drivers are protected by international human rights law. Persons displaced within their country due to disasters caused by natural or human made hazards are also covered by provisions laid out in the Guiding Principles on Internal Displacement. This coverage is contingent on the extent to which a country has adopted the Guiding Principles.

While this terminology analysis focuses on movement, it is important to note that the concept of “vulnerability” needs to be put at the centre of current and future responses to environmental migration. The most vulnerable may be those who are unable to or do not move (trapped populations). 

Trapped populations are those “who do not migrate, yet are situated in areas under threat, […] at risk of becoming ‘trapped’ or having to stay behind, where they will be more vulnerable to environmental shocks and impoverishment. The notion of trapped populations applies in particular to poorer households who may not have the resources to move and whose livelihoods are affected” (IOM, 2019). In the context of climate change, some populations might not be able to move due lack of resources, disability or social reasons (e.g. gender issues), and other might choose not to move due cultural reasons, such as the ancestral links people have with their land.

For more information:

International Organization for Migration
2019    Glossary on Migration, International Migration Law No. 34
2014    Glossary on Migration, Environment and Climate Change: Evidence for Policy
2014    IOM Outlook on Migration, Environment and Climate Change
2007    Migration and the Environment. Discussion Note: MC/INF/288, prepared for the Ninety-fourth Session of the IOM Council, 27–30 November 2007, Geneva.

Intergovernmental Panel on Climate Change (IPCC)
2018    Glossary In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C

United Nations Framework Convention on Climate Change (UNFCCC)
2020    Glossary of Climate Change Acronyms and Terms

United Nations Office for Disaster Risk Reduction (UNDRR)
2020    Terminology on Disaster Risk Reduction