Editing IPCC:AR6/WGII/Chapter-6 (section)

==== 6.2.3.3 Migration and Differentiated Vulnerability ====

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Migration, displacement and resettlement each play a foundational role in differentiated vulnerability (see Cross-Chapter Box MIGRATE in Chapter 7). The relationship between migration and vulnerability is complex ( ''robust evidence'' , ''high agreement'' ), and is the first of the three components discussed within this section. Climate change, as a push factor, is only one among multiple drivers (political, economic and social) related to environmental migration (Heslin et al., 2019; [[#Plänitz--2019|Plänitz, 2019]] ; [[#Luetz--2019|Luetz and Merson, 2019]] ). There is consensus that it is difficult to pin climate change as the sole driver of internal (within national boundaries) rural to urban migration decisions owing to, among other factors, the disconnect between national and international policies (Wilkinson et al., 2016), the lack of unifying theoretical frameworks and the complex interactions between climatic and other drivers (social, demographic, economic and political) at multiple scales (Cattaneo et al., 2019; Borderon et al., 2019). Environmental migration, including rural to urban migration, triggered by climate change may ensue from either slow- or rapid-onset climatic events and could be either temporary, cyclical or permanent movement that occurs within or beyond national boundaries (Heslin et al., 2019; [[#Silja--2017|Silja, 2017]] ).

A range of specific studies highlight certain elements of vulnerability and migration, including the ways in which slow-onset events affect precarious, resource-dependent livelihoods (such as farming and fisheries) (Cai et al., 2016). In small town Pakistan and Colombia, heat stress increases long-term migration of men, driven by a negative effect on farm income (Mueller, Gray and Kosec, 2014; [[#Tovar-Restrepo--2013|Tovar-Restrepo and Irazábal, 2013]] ). A study from Mexico reveals that an increase in drought months led to increased rural to urban migration, while increased heat (temperature) led to a ‘nonlinear’ pattern of rural to urban migration that occurred only after extended periods of heat (nearly 34 months) (Nawrotzki et al., 2017). This aligns with other findings that a consistent increase in temperature between 2°C and 4°C in some parts of the world renders involuntary, forced migration inevitable (Otto et al., 2017).

The complexity of migration drivers (as push or pull factors) explains why there is little agreement around quantitative estimates on migration (especially international) triggered by climate change ( [[#Silja--2017|Silja, 2017]] ; Otto et al., 2017), and why estimates of future displacement attributed to climate change and other environmental causes vary between 25 million and 1 billion in 2050 (Heslin et al., 2019). Many authors are critical of existing perspectives on climate-related migration, and argue for more nuanced research on the topic (Boas et al., 2019; [[#Kaczan--2020|Kaczan and Orgill-Meyer, 2020]] ; [[#Silja--2017|Silja, 2017]] ; Sakdapolrak et al., 2016; [[#Singh--2020|Singh and Basu, 2020]] ; [[#Luetz--2018|Luetz and Havea, 2018]] ).

Climate-induced migration is not necessarily higher among poorer households whose mobility is more likely to be limited due to the poverty trap (i.e., lack of financial resources) ( ''high confidence'' ) (Cattaneo et al., 2019; [[#Kaczan--2020|Kaczan and Orgill-Meyer, 2020]] ; [[#Silja--2017|Silja, 2017]] ). For example, in Bangladesh, vulnerability of rural populations is increasing, so many of the poorest employ migration as a strategy of last resort ( [[#Paprocki--2018|Paprocki, 2018]] ; Penning-Rowsell, Sultana and Thompson, 2013; [[#Adri--2018|Adri and Simon, 2018]] ) that occurs as soil salinity (as opposed to inundation alone) increases and is paralleled by economic diversification (i.e., aquaculture) ( [[#Chen--2018|Chen and Mueller, 2018]] ). There is ''robust evidence'' and ''high agreement'' that rapid-onset climatic events trigger involuntary migration and short-term, short-distance mobilities (Cattaneo et al., 2019). There is also ''robust evidence'' and ''high agreement'' that slow-onset climatic events (such as droughts and sea level rise) lead to long-distance internal displacement, more so than local or international migration ( [[#Kaczan--2020|Kaczan and Orgill-Meyer, 2020]] ; [[#Silja--2017|Silja, 2017]] ), while sea level rise is expected to lead to the displacement of communities along coastal zones, such as in Florida in the USA ( [[#Hauer--2017|Hauer, 2017]] ; Butler, Deyle and Mutnansky, 2016).

Migration, including rural–urban migration, is also recognised as an adaptation strategy in some circumstances, whether this is voluntary or planned (Jamero et al., 2019; Esteban et al., 2020a; [[#Bettini--2014|Bettini, 2014]] ). Voluntary migration can be an element of household strategies to diversify risk, depending on the nature of the climatic stress, and interacts with household composition, individual characteristics, social networks, and historical, political and economic contexts (Hunter, Luna and Norton, 2015; Carmin et al., 2015; Hayward et al., 2020). For example, in Colombia, rural to urban migration is differentiated across gender depending on the climatic stress whereby men migrate due to droughts, while women migrate due to excessive rain triggers ( [[#Tovar-Restrepo--2013|Tovar-Restrepo and Irazábal, 2013]] ). Especially in Pacific small island developing states, migration can be a strategy for urban settlements or tribal communities to relocate in customary areas, as in the case of Vunidogoloa in Fiji (McMichael, Katonivualiku and Powell, 2019; Hayward et al., 2020); it can be a livelihood strategy as shown in the Cataret Islands in Papua New Guinea ( [[#Connell--2016|Connell, 2016]] ); or it can be used to enhance education and international networks (i.e., voluntary ‘migration with dignity’) as is the case in Kiribati (Heslin et al., 2019; [[#Voigt-Graf--2017|Voigt-Graf and Kagan, 2017]] ).

The second component, displacement, also plays a crucial role in differentiated vulnerability. The lack of resources and capacities to support mobility limits the effectiveness of migration as an adaptation strategy, therefore leading to both displacement and trapped populations in the future (Adger et al., 2015; [[#Faist--2018|Faist, 2018]] ). For example, studies from Colombia ( [[#Tovar-Restrepo--2013|Tovar-Restrepo and Irazábal, 2013]] ), India ( [[#Singh--2020|Singh and Basu, 2020]] ), Mekong Delta in Vietnam ( [[#Miller--2019|Miller, 2019]] ) and Pakistan ( [[#Islam--2018|Islam and Khan, 2018]] ) showed that migration as an adaptation strategy can be constrained due to resource barriers and low mobility potential, and also, to high levels of place attachment such as in the Peruvian Highlands ( [[#Adams--2016|Adams, 2016]] ), Vanuatu ( [[#Perumal--2018|Perumal, 2018]] ) and the Tulun and Nissan Atolls of Bougainville, Papua New Guinea ( [[#Luetz--2018|Luetz and Havea, 2018]] ). Migration can also be maladaptive for the receiving contexts, whether due to the pressure on and/or conflict over land and/or the urban resources ( ''high confidence'' ) ( [[#Faist--2018|Faist, 2018]] ; [[#Singh--2020|Singh and Basu, 2020]] ; [[#Luetz--2018|Luetz and Havea, 2018]] ). Other views maintain that migration as adaptation overlooks the agency of people and their resilience, that is the nuances of ‘translocal social resilience’ ( [[#Kelman--2018|Kelman, 2018]] ; [[#Silja--2017|Silja, 2017]] ; Sakdapolrak et al., 2016). For example, the ni-Vanuatu prioritise ''in situ'' adaptation measures and leave migration as a last resort ( [[#Perumal--2018|Perumal, 2018]] ).

Regardless of the reasons and the initiators for migration, community control over resettlement both at the origin and destination leads to more positive outcomes for both the communities being resettled and the receiving communities ( ''high confidence'' ) ( [[#Perumal--2018|Perumal, 2018]] ; [[#Ferris--2015|Ferris, 2015]] ; [[#Price--2019|Price, 2019]] ; [[#Mortreux--2015|Mortreux and Adams, 2015]] ; Tadgell, Doberstein and Mortsch, 2018; [[#Luetz--2018|Luetz and Havea, 2018]] ). The protection of livelihoods contributes to ensuring the well-being (physical and mental) and the protection of the rights of communities ( ''high confidence'' ) ( [[#Ferris--2015|Ferris, 2015]] ; [[#Price--2019|Price, 2019]] ). There is ''limited evidence'' but ''high agreement'' that the outcomes of resettlement initiatives are complex and multi-faceted ( [[#Ferris--2015|Ferris, 2015]] ). For example, in Shangnan County, northwest China, the Massive Southern Shaanxi Migration Program, based on voluntary participation, reduced risk exposure and improved the quality of life in general, but also disproportionately increased the vulnerability of disadvantaged groups (the poor, migrants, and those left behind) (Lei et al., 2017). Similarly, vulnerability increased due to the loss of connection to place and community bonds in Mekong Delta, Vietnam ( [[#Miller--2019|Miller, 2019]] ), and due to unsafe construction, poor infrastructure, institutional incapacity and general neglect in resettlement initiatives in Malawi, sub-Saharan Africa ( [[#Kita--2017|Kita, 2017]] ).

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