There are multiple types of migration and multiple environmental factors – each affecting the other in various ways.

While the natural environment can contribute to attracting people to a given destination, or impact livelihoods to the extent that people’s resources to migrate are reduced and they become less mobile, the main focus of this discussion is on how environmental phenomena – both sudden and slow onset – lead people to migrate.

Linkages between migration, environment and climate change

There are many types of environmental events and processes that impact migration, ranging from earthquakes, which give little or no warning, to desertification processes, which occur over decades or longer. They can be human-induced or the result of natural processes, or a combination of the two. Climate change is a key factor of broader environmental change, often exacerbating ongoing processes of environmental degradation.

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climate change

… a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods.

Source

Environmental phenomena impacting migration are usually grouped into two broad categories, disasters and environmental change.

Disasters

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disaster

A serious disruption of the functioning of a community or a society at any scale due to hazardous events interacting with conditions of exposure, vulnerability and capacity, leading to one or more of the following: human, material, economic and environmental losses and impacts.

In other words, disasters occur when exposed and often vulnerable populations are impacted by hazards, and local response capacities are overwhelmed.

  • While “natural disasters” is an expression that is commonly used, it is in fact a misnomer: disasters are the results of how a society reduces and manages risks.
  • Hazards can be natural events. This chapter focuses on natural hazards (such as cyclones and floods) but human-induced hazards, such as industrial accidents, can also affect migration.
  • A natural hazard may or may not lead to a disaster, and a disaster may or may not trigger displacement.
  • Disasters can be sudden onset or slow onset – triggered by hazards that last seconds (earthquakes), days (cyclones), months or even years (droughts).
  • The vulnerability of people, communities and societies to hazards is mainly due to poverty, inequality and lack of preparedness.
  • Disasters often result in large-scale displacement, as people flee for survival.
  • Disasters may also result in secondary movements, when damage to homes and livelihoods is considerable, as people move first to a safe shelter or site, then to another place looking for work or accommodation.
  • People may find themselves in situations of protracted displacement when disruption is long lasting, and finding durable solutions is challenging.

Environmental change

  • Environmental change takes place over variable time scales, often decades or longer, although localized processes dependent on intense ecosystem use can be much quicker.
  • The impacts of environmental change do not affect all regions or localities in the same way. The most affected regions are drylands, mountain regions and low-elevation coastal zones (LECZs) situated less than ten metres above sea level.
  • Environmental change drives migration primarily through its negative impacts on livelihoods, notably rural livelihoods such as farming, livestock herding and fishing. Nonetheless, impacts on livelihoods in urban areas can also be severe.
Example
Environmental changes which can impact migration
  • Changes in temperature
  • Changes in precipitation
  • Changes to the availability of fresh water (such as lowering groundwater levels)
  • Sea-level rise
  • Melting of mountain glaciers
  • Thawing of buried layers of permanently frozen soil (“permafrost”)
  • Land degradation (including soil erosion, soil salinization and desertification)
  • Coastal and aquatic ecosystem degradation

The last two are driven primarily by unsustainable human usage practices, with climate change exacerbating existing degradation.

Vulnerability

In the context of disaster and environmental change, vulnerability is defined as:

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The conditions determined by physical, social, economic and environmental factors or processes which increase the susceptibility of an individual, a community, assets or systems to the impacts of hazards. 

Source

UNDRR, 2017

These factors shape people’s need to move, capacity to move, available options for moving and conditions in transit and at destination. Relatedly, resilience can be understood in relation to the capacity to cope with environmental shocks and stresses, including related socioeconomic impacts.

Mobility outcomes and characteristics

Environmental migration includes the following types of movement: disaster displacement, voluntary migration and planned relocation.

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Figure 1. Types of environmental migration

Disaster displacement

  • In most cases, displacement, whether caused by sudden- or slow-onset disasters, happens over short distances.
    For example, displaced agricultural communities in Bangladesh often move only across short distances from their residence following, for instance, loss of homes due to flooding (Shamsuddoha et al., 2011).
  • Disaster displacement is most often temporary: where conditions for safe return and sustainable reintegration exist (housing, livelihoods), most people prefer to return. Nonetheless, considerable support for rehabilitation and recovery is often needed, and protracted displacement of disaster-affected populations does occur.
    For example, many of the people displaced by the Fukushima disaster in Japan in 2011 are still unable or unwilling to return. People in situations of protracted displacement are often highly vulnerable, particularly in camp and camp-like settings.
  • Most disaster displacement occurs at a local level and within countries, but cross-border displacement does occur and poses specific challenges.
  • Displaced persons often require both short- and long-term assistance. This ranges from immediate humanitarian assistance to the provision of durable solutions to displacement (further details in Solutions and recovery).
Example
Cross-border displacement

Cross-border displacement caused by sudden-onset disasters is relatively rare, though examples exist, especially where communities close to international borders are affected. In 2002, for example, approximately 300,000 residents of Goma (Democratic Republic of the Congo) fled into neighbouring Rwanda following the eruption of the Nyiragongo volcano (Baxter and Ancia, 2002). The border with Rwanda is situated within a few kilometres of the city of Goma and affected persons had few safe evacuations options within the country.

Cross-border displacement is more prevalent in the context of slow-onset disasters such as drought. The 2011–2012 drought crisis in the Horn of Africa for example resulted in the cross-border displacement of an estimated 290,000 Somali nationals to neighbouring countries with a high proportion seeking refuge in large, existing camps run by international agencies. A further 1.3 million were internally displaced (UNHCR, 2012). The severity of the drought was compounded by a number of factors, including recurrent drought in the preceding years and increased internal conflict within Somalia which impeded humanitarian access.

Voluntary migration

  • Most voluntary environmental migration takes place within countries (internal migration), often from rural to urban areas or rural to rural areas, as a result of increasing pressure on rural livelihoods linked to environmental change and in conjunction with other (mainly economic) drivers of migration.
  • Where movements do involve crossing an international border, the majority are to neighbouring countries. In some cases, rural–urban migration may be a stepping stone to international migration at a later stage.
  • Voluntary” migration also can occur after initial displacement caused by disasters, especially when return is not yet possible (for instance, as a result of limited access to livelihoods).
    However, following disasters, the distinction between migration and secondary displacement may be difficult to make, since there is probably a forced element to migration even when undertaken voluntarily as a coping strategy.
Example
Migratory responses to the Haiti earthquake

The Haiti earthquake of 2010 provides an illustrative example of the complex, multistage migratory movements linked to disasters. Approximately 630,000 of the 2.3 million Haitians displaced by the earthquake initially left Port-au-Prince, the capital (the most affected area) for other parts of the country. A significant number of Haitians moved internationally, with many crossing the local border into the Dominican Republic. Many others moved further afield to countries with a strong diaspora presence and employment opportunities. For example, more than 10,000 Haitians moved to Brazil between 2010 and 2013, passing through various countries on the way (many of which allowed visa-free entry for Haitians).

Source

IDMC, 2012; IOM Regional Office for South America, 2014; Weiss Fagen, 2013.

  • Voluntary migration in the context of disasters and environmental change can be temporary or permanent:
    • The movement is often of a designated member(s) of the household and more likely to be toward urban centres or employment hubs.
    • Migration is a common response to environmental pressures such as reduced crop yield or failed harvests.
      In areas subject to annual dry or rainy seasons (or in the tropics, annual cyclone season) seasonal migration is a common and integral part of livelihood systems. It is usually local, rural–rural migration, and is often essential to food security. Timing of movements is often linked to agricultural cycles, with people migrating away from home during times of low demand for work (often the dry season) to areas with different agricultural cycles, more favourable weather conditions, labour shortage caused by outmigration, or a combination of these.
  • Permanent migration is more likely at advanced stages of environmental degradation, as slow processes such as sea-level rise and desertification gradually render livelihoods unsustainable or areas inhabitable.
  • Migration can be a significant factor for reducing vulnerability and building household resilience, particularly when planned.

Planned relocation

Planned relocation can be an effective pre-emptive intervention for reducing the exposure of vulnerable populations (and assets) to disasters and severe environmental degradation (further details on Planned relocation in Managing environmental migration below, in this chapter).

  • Relocation is typically a collective movement of a community or a part of it, but may take place in successive steps over long timeframes. Relocation can be organized by the community affected or – more commonly – with the support of public authorities. Due to the costly nature of relocation, in terms of acquiring land, housing and re-establishing livelihoods, some form of support is usually needed.
  • To date, relocation in the context of disasters and climate change has been primarily within countries. The threat posed by sea-level rise to a number of low-lying island States raises the potential need for international relocation, which would bring additional challenges.
  • There is general agreement in research and international policy circles that relocation should be a last resort once other options have been exhausted due to the complex challenges involved.

Immobile populations

There is growing concern for those who are or might become trapped, unable to move away from areas where environmental change impacts on livelihoods.

  • It is rarely the poorest who migrate, as they do not have the financial and informational resources to do so. Their inability to move is an expression and a cause of vulnerability as not migrating from high risk areas can jeopardize their well-being.
  • In the long term, the existence of trapped populations may lead to increased recourse to (expensive) planned relocation programmes.
  • Sometimes, people choose to stay in spite of negative environmental conditions. Though some might stay because they are unable to move away, others will choose to stay – voluntary immobility – despite the challenges, for a variety of reasons (e.g. perceptions of risks and opportunities, or the strength of social or spiritual ties to home). They remain vulnerable to the impacts of environmental change.
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Figure 2. Mobility and immobility outcomes
Source

Source: Ionesco, Moknacheva and Gemmene, 2016.

Note: Conceptualized by Caroline Zickgraf and Nathalie Perrin.

Who are the most vulnerable?

Vulnerability is the product of individual, household, community and society-wide characteristics and relationships. It is related to poverty and access to power and political representation, services and opportunities: poorer people are more likely to live in areas that are more at risk, in substandard housing, to work less well-protected jobs and to have limited resources to cope with and recover from disasters. It is shaped by factors like age, gender, level of education and qualifications, access to information and existing marginalization patterns. In the context of disasters and environmental change, vulnerability often translates into a limited freedom of choice regarding mobility (such as either being compelled to move or forced to stay in place). Especially following displacement, migrants’ vulnerability can also translate into an increased risk of being trafficking (read more in the interlinkage on Trafficking in persons and the mobility dimensions of crises).

Example
Gendered impacts of disaster and environmental change in mobility outcomes

Disasters

During disasters, cultural norms and gendered power relations place women at higher risk of death and injury (Enarson, Fothergill and Peek, 2007). Women might have restricted mobility when being the primary caretakers of others with limited mobility (young children, the elderly and the ill). Further, they may have less access to resources (such as transportation, mobile phones and social networks) or skills which can be important to survive (such as swimming) and therefore will be at a disadvantage if a disaster occurs. In turn, gender norms can encourage risk-taking behaviour among men, which can increase their vulnerability.

Environmental change

Similarly, gender shapes vulnerability in the context of environmental change-related population movements, and their impacts. For instance, in Nepal, environmental changes impacting the collection of wood and fodder were associated, respectively, with higher rates of departure of men and women (Massey, Axinn and Ghimire, 2010). Migration of a male head of household can have specific negative effects for female household members left behind, such as increased workload (especially in rural areas), risk of harassment and discrimination, and early marriage of girls. Men can also experience increased vulnerabilities, linked to difficult living and working conditions in destination areas, and effects of family separation. In turn, departure of women often raises the issue of people in need of care, given women are often primary caretakers of children and the elderly (see more in Separation of families).

Livelihoods also are an important determinant of vulnerability. Rural livelihoods dependent on local natural resources are particularly vulnerable to the impacts of environmental change. At the same time, the ways in which these threats to livelihood relate to mobility are diverse.

  • Smallholders who depend on rainfall for their crops are very vulnerable to climate variability. Smallholders may lack the resources to migrate or may be pushed to migrate in conditions which increase their (and their household’s) vulnerability.
  • Pastoralists (livestock herders) are often especially vulnerable, as in addition to their shrinking access to pasture and water points, they are often marginalized and/or lack access to public decision-making and support. Although pastoralists’ livelihoods are based on mobility, environmental pressures may push them to move across greater distances. However, once certain thresholds are crossed, environmental pressures may also lead to sedentarization.

Nonetheless, it is important to look beyond this negative picture. Mobility can also be a form of adaptation that builds resilience (see more on how to minimize and address displacement in Managing environmental migration).

Key messages
  • Migration is likely to be increasingly driven by environmental change, with climate change and intensity of disasters exacerbating existing environmental degradation.
  • Human mobility outcomes in the context of disasters and environmental change are diverse: people may be displaced due to disasters; individuals or households may migrate voluntarily to adapt to the changing environment; communities may be relocated as a pre-emptive measure.
  • Environmental migration is predominantly internal; however, cross-border movements do occur, although most likely to neighbouring countries.
  • Migration, whether temporary or permanent, can be an effective coping or adaptation strategy in the face of environmental change.
  • Planned relocation should be considered as a last resort and requires long-term and careful planning.
  • The most vulnerable may be those who are unable to move out of areas adversely impacted by environmental change – trapped populations.
  • Vulnerability to environmental change (and disasters) is the product of individual, household, community and society-wide characteristics and processes. Income and gender are important determinants of vulnerability.