2.4.4.3 Forced migration

Migration, also referred to as ‘mobility’, is defined by the UN Migration Agency (IOM) as “the movement of persons away from their place of usual residence, either across an international border or within a state”, and has been a fundamental part of human behaviour for millennia (IOM, 2023). As the overarching concept of migration encapsulates both voluntary and involuntary movement, it is often split into subcategories to better contextualise. These are summarised in Table 2.4.1 . Here, the focus is on forms of forced migration.

Table 2.4.1: Definitions of migration 

Concept	Definition
Voluntary migration	Movement resulting from an active choice. This could be in response to either acute or gradual processes, both environmental and social, or purely driven by ‘pull’ factors such as the opportunity to earn a better income. Depends on income levels, demographic characteristics and access to social networks, including to individuals who have already migrated (IOM, 2019).
Displacement/ forced migration	The movement 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 generalised violence, violations of human rights and/or natural or human-made disasters (IOM, 2023).
Seasonal/ cyclic migration	Short-term movement of populations in order to ‘make use of resources outside their immediate geographical vicinities’, often repeated on a regular temporal scale (Zieba, 2017).
Refugee	Defined by international law as an individual who is fleeing persecution or conflict in their country of origin (UN, 2023).
‘Trapped’ Populations	While not technically migration as it does not involve movement, populations who would otherwise like to relocate but, for reasons outside their control (e.g. lack of resources) cannot, may become involuntarily immobile or ‘trapped’ in place. These communities are often especially vulnerable (IOM, 2023).

When faced with challenges and/or incentives (also known as push and pull factors), people and communities may desire to stay where they are or to relocate. Migration can improve people’s livelihoods, but it can also pose many challenges and hardships. Climate change may impact migration flows both directly (i.e. the local environment becomes unsuitable for favourable habitation) and indirectly (i.e. by impacting relative wages through effects on farmers’ crop yields). The combination of ‘push’ and ‘pull’ factors is key to understanding how the migration is best characterised.  

There is a risk to human mobility and social cohesion when livelihoods are threatened. This results in increased conflict, violence and shifts in migratory patterns (Mackie, E et al., 2020). Indeed, climate change is projected to increase both internal and external migration patterns dramatically in the coming years. It is therefore of increasingly urgent importance to understand the relationship between climate change, migration and conflict, especially as the potential for tipping points in the Earth system poses additional uncertainty and risks that could alter and potentially exacerbate these dynamics. 

In the context of migration, the influence and impacts of climate change are likely to be non-linear. The systems involved, therefore, will vary on a case-by-case basis. However, some consistency can be expected. In many cases, movement of people is primarily driven by socio-economic phenomena, with climate-related factors more likely to play an important multiplier role, leading to cascade events, rather than forming the single most important driver. This could initially manifest as a drought and subsequent crop failure, which, depending on the level of hunger and economic loss experienced by individuals and communities, could drive rural-to-urban migration in search of better prospects. However, it is important to note that this decision is closely linked to factors such as family structures, youth aspirations and a host of wider historical factors, alongside the impact of successive drought (Franzke et al., 2022). Depending on the scale and level of governance surrounding this movement, it is possible that tensions could arise between the new arrivals and the receiving community. In cases such as the Syrian civil war and the Chittagong Hill Tracts conflict in Bangladesh, these dynamics have been flagged as one of the potential drivers for the outbreak of violence.

Although not applied as widely as in natural systems, efforts to understand tipping points in social systems have grown in recent years (Barrett and Dannenberg, 2014; Kallus, 2014; Moat et al., 2013; Kuehn et al., 2014; Haldane and May, 2011; Neuman et al., 2011; Saavedra et al., 2011; Scheffer et al,. 2009). In the context of migration, tipping cascades can manifest as a domino effect, where an environmental or socio-political event causes displacement or voluntary migration as people search for improved living conditions and better economic opportunities.Migration and displacement are likely to create cascading risks: as populations move, perceived threat and conflict over natural and social resources in receiving communities can create new environmental and social pressures (Podesta, 2019). This is well documented in the Lake Chad Basin case, where climate change and unsustainable resource management affect the sustainability of natural resources, increasing vulnerability and leading to coping strategies such as migration (McLeman et al., 2021).  

Displacement can in turn disrupt livelihoods, human security (such as food and housing, but also exposure to violence and conflict), the social fabric of communities (Stal, 2009), and can result in further disinvestment in these communities due to a decreased tax base, population density, and representation in local politics and other post-disaster efforts (see case study of Hurricane Katrina, for an example). This can render these communities less hospitable or inhospitable for displaced populations to return to, creating a cycle that reinforces, extends or renders the displacement permanent or more disruptive, and can make them more vulnerable to future displacement (see case study). In addition, restrictive migration policies can lead to a situation of forced immobility (Sydney and Desai, 2020). Displaced populations must grapple with the loss of their livelihoods, often by identifying new temporary sources of income that can become permanent due to the challenges of and barriers to quickly returning to origin communities. Displacement can thus fracture social cohesion, erode social capital and increase the economic precarity of already-marginalised communities. Additionally, decisions to migrate are in part determined by social networks, rendering it easier for higher-income populations to engage in adaptive migration decisions, while lower-income communities face forced or involuntary displacement and immobility (Cattaneo and Peri, 2016; Dun, 2009; Dun and Gemenne, 2008). These compounding and reinforcing effects can exacerbate pre-existing social inequities, and shape the pattern of displacement (e.g. short or long-term/permanent, near or far) among different populations. 

There is also limited knowledge about the complexity of interactions and drivers of climate-induced displacement and mobility more generally, and how multiple and systemic risks compound, propagate or cascade through coupled human-environment systems (Simpson et al., 2021; Lawrence et al., 2020; Renn, 2019; Pescaroli, 2018). 

By mitigating common flash points that lead to migration-driven conflict (for example, resource scarcity, group resilience, housing stability) and proactively counteracting grievance narratives (such as state favouritism or ethnic-based identity disputes, for instance) it may be possible to reduce the post-displacement conflict risk. However, as state fragility is one of the greatest predictors of migration-related conflict, the feasibility of this in practice may be limited. In cases where displacement cannot be prevented, evidence suggests that those displaced – either by conflict or by rapid climate impacts – tend not to move long distances. In these cases, failure to provide proper and timely humanitarian relief may put pressure on local resources, creating a potential source of conflict.