Editing IPCC:AR6/WGII/Chapter-7 (section)

=== 7.2.6 Observed Impacts on Migration ===

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Consistent with peer-reviewed scholarship and with the United Nations Framework Convention on Climate Change (UNFCCC) Cancun Adaptation Framework section 14(f) and the Paris Agreement, this Chapter assesses the impacts of climate change on four types of migration: (a) adaptive migration (i.e., where migration is an outcome of individual or household choice), (b) involuntary migration and displacement (i.e., where people have few or no options except to move), (c) organised relocation of populations from sites highly exposed to climatic hazards and (d) immobility (i.e., an inability or unwillingness to move from areas of high exposure for cultural, economic or social reasons) (Cross-Chapter Box MIGRATE in Chapter 7).

''A general theme across studies from all regions is that climate-related migration outcomes are diverse'' ( ''high confidence'' ) ''and may be manifest as decreases or increases in migration flows, and may lead to changes in the timing or duration of migration and to changes in migration source locations and destinations.'' Multi-country studies of climatic impacts on migration patterns in Africa have found that migration exhibits weak, inconsistent associations with variations in temperature and precipitation and that migration responses differ significantly between countries and between rural and urban areas ( [[#Gray--2016|Gray and Wise, 2016]] ; [[#Mueller--2020|Mueller et al., 2020]] ). Multi-directional findings such as these are also common in single-country studies from multiple regions ( [[#Call--2017|Call et al., 2017]] ; [[#Nawrotzki--2017|Nawrotzki et al., 2017]] ; [[#Cattaneo--2019|Cattaneo et al., 2019]] ; [[#Kaczan--2020|Kaczan and Orgill-Meyer, 2020]] ). The diversity of potential migration and displacement outcomes reflects (a) the variable nature of climate hazards in terms of the rate of onset, intensity, duration, spatial extent and severity of damage caused to housing, infrastructure and livelihoods and (b) the wide range of social, economic, cultural, political and other non-climatic factors that influence exposure, vulnerability, adaptation options and the contexts in which migration decisions are made ( [[#Neumann--2015|Neumann and Hermans, 2015]] ; [[#McLeman--2017|McLeman, 2017]] ; [[#Barnett--2018|Barnett and McMichael, 2018]] ; [[#Cattaneo--2019|Cattaneo et al., 2019]] ; [[#Hoffmann--2020|Hoffmann et al., 2020]] ) ( ''high confidence'' ).

''Weather events and climate conditions can act as direct drivers of migration and displacement (e.g., destruction of homes by tropical cyclones) and as indirect drivers (e.g., rural income losses and/or food insecurity due to heat- or drought-related crop failures that in turn generate new population movements)'' ( ''high confidence'' ). Extreme storms, floods and wildfires are strongly associated with high levels of short- and long-term displacement, while droughts, extreme heat and precipitation anomalies are more likely to stimulate longer-term changes in migration patterns ( [[#Kaczan--2020|Kaczan and Orgill-Meyer, 2020]] ; [[#Hoffmann--2020|Hoffmann et al., 2020]] ). Longer-term environmental changes attributable to anthropogenic climate change—such as higher average temperatures, desertification, land degradation, biodiversity loss and sea level rise—have had observed effects on migration and displacement in a limited number of locations in recent decades but are projected to have wider-scale impacts on future population patterns and migration, and are therefore assessed in [[#7.3.2|Section 7.3.2]] (Projected Risks).

''The diversity of potential migration and displacement outcomes reflects the scale and physical impacts of specific climate hazard events and the wide range of social, economic, cultural, political and other non-climatic factors that influence exposure, vulnerability, adaptation options and the contexts in which migration decisions are made'' ( ''high confidence'' ) ''.'' The diversity in drivers, contexts and outcomes makes it difficult to offer simple generalisations about the relationship between climate change and migration. The characteristics of climatic drivers vary in terms of the rate of onset, intensity, duration, spatial extent and severity of damage caused to housing, infrastructure and livelihoods; the potential migration responses to these are further mediated by cultural, demographic, economic, political, social and other non-climatic factors operating across multiple scales ( [[#Neumann--2015|Neumann and Hermans, 2015]] ; [[#McLeman--2017|McLeman, 2017]] ; [[#Barnett--2018|Barnett and McMichael, 2018]] ; [[#Cattaneo--2019|Cattaneo et al., 2019]] ; [[#Hoffmann--2020|Hoffmann et al., 2020]] ).

''Climate-related migration and displacement outcomes display high variability in terms of migrant success, often reflecting pre-existing socioeconomic conditions and household wealth'' ( ''high confidence'' ) ''.'' The decision to migrate or remain in place when confronted by climatic hazards is strongly influenced by the range and accessibility of alternative, ''in situ'' (i.e., non-migration) adaptation options that may be less costly or disruptive ( [[#Cattaneo--2019|Cattaneo et al., 2019]] ). Migration decisions (whether climate-related or not) are typically made at the individual or household level and are influenced by a household’s perceptions of risk, social networks, wealth, age structure, health and livelihood choices ( [[#Koubi--2016b|Koubi et al., 2016b]] ; [[#Gemenne--2017|Gemenne and Blocher, 2017]] ). Households with greater financial resources and higher levels of educational attainment have greater capacity to adapt ''in situ'' ( [[#Cattaneo--2019|Cattaneo and Massetti, 2019]] ; [[#Ocello--2015|Ocello et al., 2015]] ) but are also better able to migrate and with greater agency once such a decision is made ( [[#Kubik--2016|Kubik and Maurel, 2016]] ; [[#Koubi--2016b|Koubi et al., 2016b]] ; [[#Riosmena--2018|Riosmena et al., 2018]] ; [[#Adams--2019|Adams and Kay, 2019]] ). By contrast, poor households with limited physical, social and financial resources have less capacity to adapt ''in situ'' and are often limited in their migration options ( [[#Nawrotzki--2018|Nawrotzki and DeWaard, 2018]] ; [[#Suckall--2017|Suckall et al., 2017]] ; [[#Zickgraf--2016|Zickgraf et al., 2016]] ). Thus, when poorer households do migrate after an extreme climate event, it is often in reaction to lost income or livelihood and occurs with low voluntarity ( [[#Mallick--2017|Mallick et al., 2017]] ; [[#Bhatta--2015|Bhatta et al., 2015]] ) and may perpetuate or amplify migrants’ socioeconomic precarity and/or their exposure to environmental hazards ( [[#Natarajan--2019|Natarajan et al., 2019]] ; see also [[IPCC:Wg2:Chapter:Chapter-8#8.3.1|Section 8.3.1]] ).

''Climate-related migration originates most often in rural areas in low- and middle-income countries, with migrant destinations usually being other rural areas or urban centres within their home countries (i.e., internal migration)'' ( ''medium confidence'' ) ''.'' Rural livelihoods and incomes based on farming, livestock rearing and/or natural resource collection are inherently sensitive to climate variability and change, creating greater potential for migration as a response ( [[#Bohra-Mishra--2017|Bohra-]] [[#Mishra--2017|Mishra et al., 2017]] ; [[#Viswanathan--2015|Viswanathan and Kumar, 2015]] ). Drought events have been associated with periods of higher rural to urban migration within Mexico ( [[#Chort--2016|Chort and de la Rupelle, 2016]] ; [[#Leyk--2017|Leyk et al., 2017]] ; [[#Nawrotzki--2017|Nawrotzki et al., 2017]] ; [[#Murray-Tortarolo--2021|Murray-Tortarolo and Martnez, 2021]] ) and Senegal ( [[#Nawrotzki--2017|Nawrotzki and Bakhtsiyarava, 2017]] ). Extreme temperatures are associated with higher rates of temporary rural out-migration in South Africa and in Bangladesh ( [[#Mastrorillo--2016|Mastrorillo et al., 2016]] ; [[#Call--2017|Call et al., 2017]] ). In rural Tanzania, weather-related shocks to crop production have been observed to increase the likelihood of migration but typically only for households in the middle of community wealth distribution ( [[#Kubik--2016|Kubik and Maurel, 2016]] ). Weather-related losses in rice production have been associated with small-percentage increases in internal migration in India ( [[#Viswanathan--2015|Viswanathan and Kumar, 2015]] ) and the Philippines ( [[#Bohra-Mishra--2017|Bohra-]] [[#Mishra--2017|Mishra et al., 2017]] ). In east Africa, temporary rural–urban labour migration does not show a strong response to climatic drivers ( [[#Mueller--2020|Mueller et al., 2020]] ). There is limited literature on mobility as adaptation in urban populations, with the focus being on resettlement of flood-prone informal settlements within cities ( [[#Kita--2017|Kita, 2017]] ; [[#Tadgell--2017|Tadgell et al., 2017]] ).

''Most documented examples of international climate-related migration are intra-regional movements of people between countries with shared borders'' ( ''high agreement, medium evidence'' ) ''.'' Systematic reviews find few documented examples of long-distance, inter-regional migration driven by climate events ( [[#Veronis--2018|Veronis et al., 2018]] ; [[#Kaczan--2020|Kaczan and Orgill-Meyer, 2020]] ; [[#Hoffmann--2020|Hoffmann et al., 2020]] ). One macro-economic analysis found a correlation between migrant flows from low- to high-income countries and adverse climatic events in the source country ( [[#Coniglio--2015|Coniglio and Pesce, 2015]] ). Another study found that high heat stimulates higher rates of international migration from middle-income countries but typically not from low-income countries (Cattaneo and Peri., 2016), while other studies found international climate-related migration originates primarily from agriculture-dependent countries ( [[#Cai--2016|Cai et al., 2016]] ; [[#Nawrotzki--2017|Nawrotzki and Bakhtsiyarava, 2017]] ). Small-sample studies of migrants to Canada from Bangladesh, Haiti and sub-Saharan Africa suggest environmental factors in the source country can be a primary or secondary motivation for some migrants within larger flows of economic and family-reunification migrants ( [[#Veronis--2014|Veronis and McLeman, 2014]] ; [[#Mezdour--2015|Mezdour et al., 2015]] ; [[#McLeman--2017|McLeman et al., 2017]] ). Research on the links between climate hazards and international movements of refugees and/or asylum seekers shows differing results. One study found that asylum applications in Europe increase during climate fluctuations due to interactions with conflict ( [[#Missirian--2017|Missirian and Schlenker, 2017]] ), and another found links between heat, drought, conflict and asylum-seeking migration originating in the Middle East between 2011 and 2015 ( [[#Abel--2019|Abel et al., 2019]] ). Other studies have found that asylum claims in Europe correspond minimally with climatic hazards in source countries ( [[#Schutte--2021|Schutte et al., 2021]] ), with choices in baseline data, timeframes for analysis and methodological approaches potentially explaining the inconsistent results across studies ( [[#Boas--2019|Boas et al., 2019]] ). Media reports and other studies in recent years suggest that climate change has driven large numbers of migrants to the US from Central America and to Europe from the Middle East and Africa, but empirical studies were not identified for this assessment.

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==== 7.2.6.1 Relative Importance of Specific Climatic Drivers of Migration and Displacement ====

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Reliable global estimates of voluntary climate-related migration within and between countries are not available due to a general absence of data of this specific nature, with existing national and global datasets often lacking information on migration causation or motivation. Better data are available for involuntary displacements within countries for reasons associated with weather-related hazards. Data collected annually since 2008 on internal displacements attributed to extreme weather events by the IDMC indicate that extreme storms and floods are the two most significant weather-related drivers of population displacements globally. Because of improvements in collection sources and methods since it first began reporting data in 2008, upward trends since that year in the total reported annual number of people displaced should be treated cautiously. However, it is reasonable to conclude that the average annual rate currently exceeds 20 million people globally, with considerable interannual variation due to the frequency and severity of extreme events in heavily populated areas. Regional distribution of displacement events has been consistent throughout the IDMC data collection period ( ''high confidence'' ), with displacement events occurring most often in East, Southeast and south Asia; sub-Saharan Africa; the USA; and the Caribbean region (Figure 7.7). Relative to their absolute population size, small island states experience a disproportionate risk of climate-related population displacements ( [[#Desai--2021|Desai et al., 2021]] ) ( ''high confidence'' ).

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[[File:dced250ee7e0192c3947a11687d10b79 IPCC_AR6_WGII_Figure_7_007.png]]

'''Figure 7.7 |''' '''Average number of people displaced annually by selected weather-related events from 2010 to 2020 by region.''' See text for important notes regarding data collection and trends. Source statistics provided by the Internal Displacement Monitoring Centre ( https://www.internal-displacement.org/ ).

''Tropical cyclones and extreme storms are a particularly significant displacement risk in East and Southeast Asia, the Caribbean region, the Bay of Bengal region and southeast Africa (IDMC 2020)'' ( ''high confidence'' ) ''.'' The scale of immediate displacement from any given storm and potential for post-event migration depend heavily on the extent of damage to housing and livelihood assets and the responsive capacity of governments and humanitarian relief agencies ( [[#Saha--2016|Saha, 2016]] ; [[#Islam--2018|Islam et al., 2018]] ; Mahajan, 2020; [[#Spencer--2018|Spencer and Urquhart, 2018]] ). In Bangladesh, the rural poor are most often displaced, with initial increases in short-term, labour-seeking migration followed by more permanent migration by some groups ( [[#Saha--2016|Saha, 2016]] ; [[#Islam--2016|Islam and Hasan, 2016]] ; [[#Islam--2017|Islam and Shamsuddoha, 2017]] ). Past hurricanes in the Caribbean basin have generated internal and inter-state migration within the region, typically along pre-existing social networks, and to the USA ( [[#Loebach--2016|Loebach, 2016]] ; [[#Chort--2016|Chort and de la Rupelle, 2016]] ). In 2017, Hurricanes Irma and Maria caused widespread damage to infrastructure and health services, and a slow recovery response by authorities was followed by the migration of tens of thousands of Puerto Ricans to Florida and New York ( [[#Zorrilla--2017|Zorrilla, 2017]] ; [[#Echenique--2018|Echenique and Melgar, 2018]] ). In the US, coastal counties experience increased out-migration after hurricanes that flows along existing social networks ( [[#Hauer--2017|Hauer, 2017]] ), with post-disaster reconstruction employment opportunities potentially attracting new labour migrants to affected areas ( [[#Ouattara--2014|Ouattara and Strobl, 2014]] ; [[#Curtis--2015|Curtis et al., 2015]] ; [[#DeWaard--2016|DeWaard et al., 2016]] ; [[#Fussell--2018|Fussell et al., 2018]] ).

''Riverine flood displacement can lead to increases or decreases in temporary or short-distance migration flows, depending on the local context'' ( ''medium confidence'' ) ''( [[#Robalino--2015|Robalino et al., 2015]] ; [[#Ocello--2015|Ocello et al., 2015]] ; [[#Afifi--2016|Afifi et al., 2016]] ; [[#Koubi--2016b|Koubi et al., 2016b]] )'' . Floods are a particularly important driver of displacement in river valleys and deltas in Asia and Africa, although large flood-related displacements have been recorded by the IDMC in all regions. In Africa, populations exposed to low flood risks, as compared with other regions, are observed to have a greater vulnerability to displacement due to limited economic resources and adaptive capacity ( [[#Kakinuma--2020|Kakinuma et al., 2020]] ). In areas where flooding is especially frequent, ''in situ'' adaptations may be more common, and out-migration may temporarily decline after a flood ( [[#Afifi--2016|Afifi et al., 2016]] ; [[#Chen--2017|Chen et al., 2017]] ; [[#Call--2017|Call et al., 2017]] ). Rates of indefinite or permanent migration tend not to change following riverine floods unless damage to homes and livelihood assets is especially severe and widespread, with household perceptions of short- and longer-term risks playing an important role ( [[#Koubi--2016a|Koubi et al., 2016a]] ).

Displacements due to droughts, extreme heat and associated impacts on food and water security are most frequent in east Africa and, to a lesser extent, south Asia and west and southern Africa (IDMC, 2020). Since droughts unfold progressively and typically do not cause permanent damage to housing or livelihood assets, there is greater opportunity for government and non-governmental organisation (NGO) interventions and greater use of ''in situ'' adaptation options ( [[#Koubi--2016b|Koubi et al., 2016b]] ; [[#Koubi--2016a|Koubi et al., 2016a]] ; [[#Cattaneo--2019|Cattaneo et al., 2019]] ). Drought-related population movements are most common in dryland rural areas of low-income countries and occur after a threshold is crossed and ''in situ'' adaptation options are exhausted ( [[#Gautier--2016|Gautier et al., 2016]] ; [[#Wiederkehr--2018|Wiederkehr et al., 2018]] ; [[#McLeman--2017|McLeman, 2017]] ). Observed population movements may occur for an extended period after the event; one study of Mexican data found this lag to be up to 36 months ( [[#Nawrotzki--2017|Nawrotzki et al., 2017]] ). The most common response to drought is an increase in short-distance, rural–urban migration ( ''medium confidence'' ), with examples being documented in Bangladesh, Ethiopia, Pakistan, sub-Saharan Africa, Latin America and Brazil ( [[#Neumann--2015|Neumann and Hermans, 2015]] ; [[#Gautier--2016|Gautier et al., 2016]] ; [[#Gautier--2016|Gautier et al., 2016]] ; [[#Mastrorillo--2016|Mastrorillo et al., 2016]] ; [[#Baez--2017|Baez et al., 2017]] ; [[#Call--2017|Call et al., 2017]] ; [[#Nawrotzki--2017|Nawrotzki et al., 2017]] ; [[#Jessoe--2018|Jessoe et al., 2018]] '';'' [[#Carrico--2019|Carrico and Donato, 2019]] ; [[#Hermans--2019|Hermans and Garbe, 2019]] ).

Few assessable studies were identified that examine links between wildfires and migration. Wildfire events are often associated with urgent evacuations and temporary relocations, which place significant stress on receiving communities (Spearing and Faust., 2020), but research in the USA suggests fires have only a modest influence on future migration patterns in exposed areas (Winkler and Rouleau., 2021). More research, particularly in other regions, is needed.

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==== 7.2.6.2 Immobility and Resettlement in the Context of Climatic Risks ====

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''Immobility in the context of climatic risks can reflect vulnerability and lack of agency (an inability to migrate), but can also be a deliberate choice'' ( ''high confidence'' ) ''.'' Research since AR5 shows that immobility is best described as a continuum from people who are financially or physically unable to move away from hazards (involuntary immobility) to people who choose not to move (voluntary immobility) because of strong attachments to place, culture and people ( [[#Nawrotzki--2018|Nawrotzki and DeWaard, 2018]] ; [[#Adams--2016|Adams, 2016]] ; [[#Farbotko--2019|Farbotko and McMichael, 2019]] ; [[#Zickgraf--2019|Zickgraf, 2019]] ; [[#Neef--2018|Neef et al., 2018]] ; [[#Suckall--2017|Suckall et al., 2017]] ; [[#Ayeb-Karlsson--2018|Ayeb-Karlsson et al., 2018]] ; [[#Zickgraf--2018|Zickgraf, 2018]] ; [[#Mallick--2020|Mallick and Schanze, 2020]] ). Involuntary immobility is associated with individuals and households with low adaptive capacity and high exposure to hazard, and can exacerbate inequality and future vulnerability to climate change ( [[#Sheller--2018|Sheller, 2018]] ), including through impacts on health ( [[#Schwerdtle--2018|Schwerdtle et al., 2018]] ). Voluntary immobility represents an assertion of the importance of culture, livelihoods and people to well-being, and is of particular relevance for Indigenous Peoples ( [[#Suliman--2019|Suliman et al., 2019]] ).

Planned relocations by governments of settlements and populations exposed to climatic hazards are not presently commonplace, although the need is expected to grow in coming decades (Hino et al 2017). Examples include relocations of coastal settlements exposed to storm and erosion hazards as well as smaller numbers of cases of flood-prone settlements in river valleys; these examples suggest that organised relocations are expensive, contentious, create multiple challenges for governments and generate short- and longer-term disruptions for the people involved ( ''high agreement, medium evidence'' ) ( [[#Ajibade--2020|Ajibade et al., 2020]] ; [[#Henrique--2020|Henrique and Tschakert, 2020]] ; [[#Desai--2021|Desai et al., 2021]] ).

Examples of relocations of small indigenous communities in coastal Alaska and villages in the Solomon Islands and Fiji suggest that relocated people experience significant financial and emotional distress as cultural and spiritual bonds to place and livelihoods are disrupted ( [[#Albert--2018|Albert et al., 2018]] ; [[#Neef--2018|Neef et al., 2018]] ; [[#McMichael--2020|McMichael and Katonivualiku, 2020]] ; [[#McMichael--2020|McMichael and Katonivualiku, 2020]] ; [[#McMichael--2021|McMichael et al., 2021]] ; [[#Piggott-McKellar--2019|Piggott-McKellar et al., 2019]] ; [[#Bertana--2020|Bertana, 2020]] ). Voluntary relocation programmes offered by US state governments in communities damaged by Hurricane Sandy in 2012 have been subject to multiple studies, and these show longer-term economic outcomes, social connections and mental well-being vary for a range of reasons unrelated to the impacts of the hazard event itself ( [[#Bukvic--2017|Bukvic and Owen, 2017]] ; [[#Binder--2019|Binder et al., 2019]] ; Koslov and Merdjanoff, 2021).

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==== 7.2.6.3 Connections Between Climate-Related Migration and Health ====

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The number of assessable peer-reviewed studies that make connections between climate-related migration and health and well-being is small. The health outcomes of migrants generally, and of climate-migrants in particular, vary according to geographical context, country and the particular circumstances of migration or immobility ( [[#Hunter--2017|Hunter and Simon, 2017]] ; [[#Hunter--2021|Hunter et al., 2021]] ; [[#Schwerdtle--2020|Schwerdtle et al., 2020]] ). Such linkages are ‘multi-directional’, with studies suggesting that healthy individuals may be more likely to migrate internationally in search of economic opportunities than people in poorer health, except during adverse climatic conditions when migration rates may change across all groups, and that migrants may have different long-term health outcomes than people born in destination areas, potentially displaying a range of positive and negative health outcomes compared to non-migrants ( [[#Kennedy--2015|Kennedy et al., 2015]] ; [[#Dodd--2017|Dodd et al., 2017]] ; [[#Hunter--2017|Hunter and Simon, 2017]] ; [[#Riosmena--2017|Riosmena et al., 2017]] ). Refugees and other involuntary migrants often experience higher exposure to disease and malnutrition, adverse indirect health effects of changes in diet or activity and increased rates of mental health concerns. These latter may be attributable to a sense of loss or fear ( [[#Schwerdtle--2018|Schwerdtle et al., 2018]] ; [[#Torres--2017|Torres and Casey, 2017]] ) as well as due to the interruption of healthcare; occupational injuries; sleep deprivation; non-hygienic lodgings and insufficient sanitary facilities; heightened exposure to vector- and WBDs; vulnerability to psychosocial, sexual and reproductive issues; behavioural disorders; substance abuse; and violence ( [[#Farhat--2018|Farhat et al., 2018]] ; [[#Wickramage--2018|Wickramage et al., 2018]] ) ''(high confidence)'' . Linkages between climate migration and the spread of infectious disease are bidirectional; migrants may be exposed to diseases at the destination to which they have lower immunity than the host community; in other cases, migrants could introduce diseases to the receiving community ( [[#McMichael--2015|McMichael, 2015]] ). Thus, receiving areas may have to pay greater attention to building migrant sensitive health systems and services ( [[#Hunter--2017|Hunter and Simon, 2017]] ). The risk of migration leading to disease transmission is exacerbated by weak governance and lack of policy to support public health measures and access to medicines ( [[#Pottie--2015|Pottie et al., 2015]] ).

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'''Cross-Chapter Box MIGRATE | Climate-Related Migration'''
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Authors: David Wrathall (USA, Chapter 8), Robert McLeman (Canada, Chapter 7), Helen Adams (United Kingdom, Chapter 7), Ibidun Adelekan (Nigeria, Chapter 9), Elisabeth Gilmore (USA/Canada, Chapter 14), François Gemenne (Belgium, Chapter 8), Nathalie Hilmi (Monaco, Chapter 18), Ben Orlove (USA, Chapter 17), Ritwika Basu (India/United Kingdom, Chapter 18), Halvard Buhaug (Norway, Chapter 16), Edwin Castellanos (Guatemala, Chapter 12), David Dodman (United Kingdom, Chapter 6), Felix Kanungwe Kalaba (Zambia, Chapter 9), Rupa Mukerji (Switzerland/India, Chapter 18), Karishma Patel (USA, Chapter 1), Chandni Singh (India, Chapter 10), Philip Thornton (United Kingdom, Chapter 5), Christopher Trisos (South Africa, Chapter 9), Olivia Warrick (New Zealand, Chapter 15), Vishnu Pandey (Nepal, Chapter 4)

'''Key messages on migration in this report'''
Migration is a universal strategy that individuals and households undertake to improve well-being and livelihoods in response to economic uncertainty, political instability and environmental change ( ''high confidence'' ). Migration, displacement and immobility that occur in response to climate hazards are assessed in general in Chapter 7, with specific sectoral and regional dimensions of climate-related migration assessed in sectoral and regional Chapters 5 to 15 (Table MIGRATE.1 in Chapter 7) and involuntary immobility and displacement being identified as representative key risks in [[IPCC:Wg2:Chapter:Chapter-16|Chapter 16]] (Sections 16.2.3.8, 16.5.2.3.8). Since AR5 there has been a considerable expansion in research on climate–migration linkages, with five key messages from the present assessment report warranting emphasis.

''Climatic conditions, events and variability are important drivers of migration and displacement'' ( ''high confidence'' ) ''(Table MIGRATE.1 in Chapter 7), with migration responses to specific climate hazards being strongly influenced by economic, social, political and demographic processes'' ( ''high confidence'' ) ''(Sections 7.2.6, 8.2.1.3).'' Migration is among a wider set of possible adaptation alternatives and often emerges when other forms of adaptation are insufficient (Sections 5.5.1.1, 5.5.3.5, 7.2.6, 8.2.1.3, 9.7.2). Involuntary displacement occurs when adaptation alternatives are exhausted or not viable and reflects non-climatic factors that constrain adaptive capacity and create high levels of exposure and vulnerability ( ''high confidence'' ) (Cross-Chapter Box SLR in Chapter 3; Sections 4.3.7, 7.2.6; Box 8.1; [[IPCC:Wg2:Chapter:Chapter-10#10.3|Section 10.3]] ; Box 14.7). There is strong evidence that climatic disruptions to agricultural and other rural livelihoods can generate migration ( ''high confidence'' ) (Sections 5.5.4, 8.2.1.3, 9.8.3; Box 9.8).

''Specific climate events and conditions may cause migration to increase, decrease or flow in new directions (high confidence), and the more agency migrants have (i.e., the degree of voluntarity and freedom of movement), the greater the potential benefits for sending and receiving areas'' ( ''high agreement, medium evidence'' ) ''(Sections 5.5.3.5, 7.2.6, 8.2.1.3; Box 12.2)'' . Conversely, displacement or low-agency migration is associated with poor outcomes in terms of health, well-being and socioeconomic security for migrants and returns fewer benefits to sending or receiving communities ( ''high agreement, medium evidence'' ) (Sections 4.3.7, 4.5.7; Box 8.1; Sections 9.7.2, 10.3; Box 14.7).

''Most climate-related migration and displacement observed currently takes place within countries'' ( ''high confidence'' ) ''(Sections 4.3.7, 4.5.7, 5.12.2, 7.2.6).'' The climate hazards most commonly associated with displacement are tropical cyclones and flooding in most regions, with droughts being an important driver in sub-Saharan Africa, parts of south Asia and South America ( ''high confidence'' ) (Sections 7.2.6.1, 9.7.2, 10.4.6.3, 11.4.1, 12.5.8.4, 13.8.1.3, 14.4.7.3). Currently, observed international migration associated with climatic hazards is considerably smaller relative to internal migration and is most often observed as flowing between states that are contiguous and have labour-migration agreements and/or longstanding cultural ties ( ''high agreement, robust evidence'' ) (Sections 4.3.7, 4.5.7, 5.12.2, 7.2.6).

''In many regions, the frequency and/or severity of floods, extreme storms and droughts is projected to increase in coming decades, especially under high-emissions scenarios (WGI AR6 [[IPCC:Wg2:Chapter:Chapter-12|Chapter 12]] (Ranasinghe et al. 2021)), raising future risk of displacement in the most exposed areas'' ( ''high confidence'' ) ''( [[#7.3.2.1|Section 7.3.2.1]] ).'' The additional impacts of climate change anticipated to generate future migration and displacement include mean sea level rise that increases flooding and saltwater contamination of soil and/or groundwater in low-lying coastal areas and small islands ( ''high confidence'' ) ( [[#7.3.2.1|Section 7.3.2.1]] ; Cross-Chapter Box SLR in Chapter 3) and more frequent extreme heat events that threaten the habitability of urban centres in the tropics and arid/semiarid regions ( ''medium confidence'' ), although the causal links between heat and migration are less clear ( [[#7.3.2.1|Section 7.3.2.1]] ).

''There is growing evidence about the future prospects of immobile populations: groups and individuals that are unable or unwilling to move away from areas highly exposed to climatic hazards'' ( ''high confidence'' ) ''(Sections 4.6.9, 7.2.6.2; Box 8.1; Box 10.2).'' Involuntarily immobile populations may be anticipated to require government interventions to continue living in exposed locations or to relocate elsewhere ( ''high agreement, medium evidence)'' (Box 8.1). Managed retreat and organised relocations of people from hazardous areas in recent years have proven to be politically and emotionally charged, socially disruptive and costly ( ''high confidence'' ) ( [[#7.4.5|Section 7.4.5.4]] ).

'''Climate-migration interactions and outcomes'''
Figure MIGRATE.1 in [https://www.ipcc.ch/report/ar6/wg2/chapter/chapter-7 Chapter 7] presents a simplified framework for understanding how migration and displacement may emerge from the interactions of climatic and non-climatic factors, based on the characteristic risk framework introduced in [[IPCC:Wg2:Chapter:Chapter-1|Chapter 1]] ( [[IPCC:Wg2:Chapter:Chapter-1#1.3|Section 1.3]] ). Voluntary migration can be used by households when adapting to climate hazards, while less voluntary forms of migration and displacement emerge when other forms of adaptation (referred to in Figure MIGRATE.1 in [https://www.ipcc.ch/report/ar6/wg2/chapter/chapter-7 Chapter 7] as ''in situ'' adaptation) are inadequate. Migration outcomes—expressed in Figure MIGRATE.1 in [https://www.ipcc.ch/report/ar6/wg2/chapter/chapter-7 Chapter 7] as changes in future risks to the well-being of migrants, sending communities and destination communities—are heavily influenced by the political, legal, cultural and socioeconomic conditions under which migration occurs. Groups and individuals that are involuntarily immobile may find that their exposure, vulnerability and risk increase over time. Table MIGRATE.1 in [https://www.ipcc.ch/report/ar6/wg2/chapter/chapter-7 Chapter 7] summarises the range of potential migration outcomes that may emerge from this dynamic and indicates specific sections in sectoral and regional chapters of the report that describe examples of each.

[[File:16246073a934a256ab78d557dfdba8c5 IPCC_AR6_WGII_Figure_7_Migrate_1.png]]

'''Figure MIGRATE.1 |''' '''General interactions between climatic and non-climatic processes, adaptation, potential migration outcomes and implications for future risk.''' Adapted from [[#McLeman--2021|McLeman et al. (2021)]] .

'''Table MIGRATE.1 |''' Typology of climate-related migration and examples in sectoral and regional chapters of AR6.

{| class="wikitable"
|-
! '''Type of climate-related migration'''

! '''Characteristics'''

! '''Recent or current examples'''

! '''Examples in the literature'''

! '''References in AR6 WGII'''

|-
| Temporary and/or seasonal migration

| Frequently used as a risk-reduction strategy by rural households in less-developed regions with highly seasonal precipitation; includes transhumance

| Pastoralists in sub-Saharan Africa; seasonal farm workers in south Asia; rural–urban labour migration in Central America

| [[#Afifi--2016|Afifi et al. (2016)]] ; [[#Call--2017|Call et al. (2017)]] ; Piguet et al. (2018); [[#Borderon--2019|Borderon et al. (2019)]] ; [[#Cattaneo--2019|Cattaneo et al. (2019)]] ; [[#Hoffmann--2020|Hoffmann et al. (2020)]] ; [[#Lopez-i-Gelats--2015|Lopez-i-Gelats et al. (2015)]] ; [[#Lu--2016|Lu et al. (2016)]] [[#Kaczan--2020|Kaczan and Orgill-Meyer (2020)]]

| Sections 5.5.1.1, 5.5.3.5; [[#7.2.6|Section 7.2.6]] ; [[IPCC:Wg2:Chapter:Chapter-8#8.2.1|Section 8.2.1.3]] ; [[IPCC:Wg2:Chapter:Chapter-9#9.8.3|Section 9.8.3]] ; Box 13.2

|-
| Indefinite or permanent migration

| Less common than temporary or seasonal migration, particularly when the whole household permanently relocates

| Numerous examples in all regions

| See reviews listed in cell above

| [[#7.2.6|Section 7.2.6]] ; [[IPCC:Wg2:Chapter:Chapter-8#8.2.1|Section 8.2.1.3]] ; Box 10.2

|-
| Internal migration

| Movements within state borders; most common form of climate-related migration

| Numerous examples in all regions

| See reviews listed in cell above

| [[IPCC:Wg2:Chapter:Chapter-4#4.3.7|Section 4.3.7]] ; Sections 5.5.4, 5.10.1.1; [[#7.2.6|Section 7.2.6]] ; Sections 9.7.2, 9.11; Box 9.8; Sections 10.3.3, 10.4.6.3, Box 10.2; [[IPCC:Wg2:Chapter:Chapter-11#11.4.1|Section 11.4.1]] ; [[IPCC:Wg2:Chapter:Chapter-12#12.5.8.4|Section 12.5.8.4]] ; [[IPCC:Wg2:Chapter:Chapter-13#13.8.1.3|Section 13.8.1.3]] ; [[IPCC:Wg2:Chapter:Chapter-14#14.4|Section 14.4.7.3]] ; [[IPCC:Wg2:Chapter:Chapter-15#15.3.4.6|Section 15.3.4.6]]

|-
| International migration

| Less common than internal migration; most often occurs between contiguous countries within the same region; often undertaken for purpose of earning wages to remit home

| Cross-border migration within south and Southeast Asia, sub-Saharan Africa

| See reviews listed in cell above; also [[#Veronis--2018|Veronis et al. (2018)]] ; [[#McLeman--2019|McLeman (2019)]] ; Cattaneo and G. (2016); [[#Missirian--2017|Missirian and Schlenker (2017)]] ; [[#Schutte--2021|Schutte et al. (2021)]]

| Sections 4.3.7, 4.5.7; [[IPCC:Wg2:Chapter:Chapter-5#5.12.2|Section 5.12.2]] ; [[#7.2.6|Section 7.2.6]]

|-
| Rural–urban or rural–rural

| Typically internal but may also flow between contiguous states; may be for temporary or indefinite periods; migration may be undertaken by an individual household member or the entire household; may be followed by remittances

| Drought migration in Mexico, east Africa and south Asia

| See reviews in the cell above; also [[#Adger--2015|Adger et al. (2015)]] ; Gautier et al. (2016); [[#Nawrotzki--2017|Nawrotzki et al. (2017)]] ; Wiederkehr et al. (2018); Robalino et al. (2015); [[#Borderon--2019|Borderon et al. (2019)]] ; [[#Murray-Tortarolo--2021|Murray-Tortarolo and Martnez (2021)]]

| [[IPCC:Wg2:Chapter:Chapter-5#5.13.4|Section 5.13.4]] ; [[#7.2.6|Section 7.2.6]] ; [[IPCC:Wg2:Chapter:Chapter-6#6.2.4.3|Section 6.2.4.3]] ; [[IPCC:Wg2:Chapter:Chapter-8#8.2.1|Section 8.2.1.3]] ; [[IPCC:Wg2:Chapter:Chapter-9#9.8.1|Section 9.8.1.2]] ; [[IPCC:Wg2:Chapter:Chapter-12#12.5.8.4|Section 12.5.8.4]] ; [[IPCC:Wg2:Chapter:Chapter-14#14.4|Section 14.4.7.1]]

|-
| Displacement

| Households are forced to leave homes for temporary or indefinite period; typically occurs as a result of extreme events and starts with seemingly temporary evacuation; risk is expected to rise in most regions due to sea level rise and changes in associated coastal hazards

| Tropical cyclones in the Caribbean, Southeast Asia and Bay of Bengal region

| [[#Islam--2017|Islam and Shamsuddoha (2017)]] ; [[#Desai--2021|Desai et al. (2021)]] ; see Internal Displacement Monitoring Centre annual reports for global statistics

| Cross-Chapter Box SLR in Chapter 3; [[IPCC:Wg2:Chapter:Chapter-4#4.3.7|Section 4.3.7]] ; 4.5.7; Cross-Chapter Box MOVING PLATE in Chapter 5; [[#7.2.6.1|Section 7.2.6.1]] ; Box 8.1; [[IPCC:Wg2:Chapter:Chapter-9#9.7.2|Section 9.7.2]] ; [[IPCC:Wg2:Chapter:Chapter-9#9.9.2|Section 9.9.2]] ; [[IPCC:Wg2:Chapter:Chapter-10#10.3|Section 10.3]] ; Box 14.7; Sections 15.3.4.6;

[https://www.ipcc.ch/chapter/7#CCP2.2 CCP2.2.2]

|-
| Planned and/or organised resettlement

| Initiated in areas where settlements become permanently uninhabitable; requires assistance from governments and/or institutions; government-sponsored sedentarisation of pastoral populations

| Fiji, Carteret Islands, Papua New Guinea, Gulf of Mexico coast and coastal Alaska, USA

| [[#Marino--2015|Marino and Lazrus (2015)]] ; Hino et al. (2017); [[#McNamara--2018|McNamara et al. (2018)]] ; [[#McMichael--2020|McMichael and Katonivualiku (2020)]] ; Tadgell et al. (2017); [[#Arnall--2014|Arnall (2014)]] ; [[#Wilmsen--2015|Wilmsen and Webber (2015)]]

| [[IPCC:Wg2:Chapter:Chapter-4#4.6.9|Section 4.6.9]] ; Sections 5.14.1, 5.14.2; [[#7.4.4.4|Section 7.4.4.4]] ; [[IPCC:Wg2:Chapter:Chapter-10#10.4|Section 10.4.6]] ; [[IPCC:Wg2:Chapter:Chapter-15#15.5.3|Section 15.5.3]] ; [https://www.ipcc.ch/chapter/7#CCP2.2 CCP2.2.2] ; [https://www.ipcc.ch/chapter/7#CCP6.3.2 CCP6.3.2]

|-
| Immobility

| Adverse weather or climatic conditions warrant moving, but households are unable to relocate because of lack of resources or choose to remain because of strong social, economic or cultural attachments to place

| Examples in most regions

| [[#Adams--2016|Adams (2016)]] ; [[#Zickgraf--2018|Zickgraf (2018)]] ; [[#Nawrotzki--2018|Nawrotzki and DeWaard (2018)]] ; [[#Farbotko--2020|Farbotko et al. (2020)]]

| [[IPCC:Wg2:Chapter:Chapter-4#4.6.9|Section 4.6.9]] ; [[#7.2.6.2|Section 7.2.6.2]] ; Box 8.1; Box 10.2

|}

'''Policy implications'''
''Future migration and displacement patterns in a changing climate will depend not only on the physical impacts of climate change, but also on future policies and planning at all scales of governance'' ( ''high confidence'' ) ''(4.6.9, 5.14.1, 5.14.1.2, 7.3.2, 7.4.4, 8.2.1.3; Box 8.1; [https://www.ipcc.ch/chapter/7#CCP6.3.2 CCP6.3.2] ).'' Policy interventions can remove barriers to and expand the alternatives for safe, orderly and regular migration that allows vulnerable people to adapt to climate change ( ''high confidence'' ) ( [[#7.2.6|Section 7.2.6]] ). With adequate policy support, migration in the context of climate change can result in synergies for both adaptation and development (Sections 5.12.2, 7.4.4, 8.2.1.3). Migration governance at local, national and international levels will influence the outcomes of climate-related migration for the migrants themselves as well as for receiving and origin communities (Sections 5.13.4, 7.4.4, 8.2.1.3). At the international level, a number of relevant policy initiatives and agreements, including Global Compacts for Safe, Orderly and Regular Migration and for the protection of Refugees; the Warsaw International Mechanism of the UNFCCC; the Sustainable Development Goals; the Sendai Framework for Disaster Risk Reduction; and the Platform on Disaster Displacement, have already been established, merit continued pursuit and provide potential migration governance pathways ( [[#7.4.4|Section 7.4.4]] ). Policy and planning decisions at regional, national and local scales that relate to housing, infrastructure, water provisioning, schools and healthcare are relevant for successful integration of migrants into receiving communities (Sections 5.5.4, 5.10.1.1, 5.12.2, 9.8.3). Policies and practices on movements of people across international borders are also relevant to climate-related migration, with restrictions on movement having implications for the adaptive capacity of communities exposed to climate hazards ( [[#7.4.4.2|Section 7.4.4.2]] ; Box 8.1). Perceptions of migrants and the framing of policy discussions in receiving communities and nations are important determinants of the future success of migration as an adaptive response to climate change ( [[#7.4.4.3|Section 7.4.4.3]] ) ( ''high agreement, medium evidence'' ).

<div id="_idContainer033" class="Box_Header-continued"></div>

Cross-Chapter Box MIGRATE

''Reducing the future risk of large-scale population displacements, including those requiring active humanitarian interventions and organised relocations of people, requires the international community to meet the requirements of the Paris Agreement and take further action to control future warming'' ( ''high confidence'' ) ''(Cross-Chapter Box SLR in Chapter 3; [[#7.3.1|Section 7.3.1]] ; Box 8.1).'' Current emissions pathways lead to scenarios for the period between 2050 and 2100 in which hundreds of millions of people will be at risk of displacement due to rising sea levels, floods, tropical cyclones, droughts, extreme heat, wildfires and other hazards, with land degradation exacerbating these risks in many regions ( [[#7.3.2|Section 7.3.2]] ; IPCC 2019b; Cross-Chapter Box SLR in Chapter 3). At high levels of warming, tipping points may exist, particularly related to sea level rise, that, if crossed, would further increase the global population potentially at risk of displacement (Ranasinghe et al. 2021). Populations in low-income countries and small-island states that have historically had low greenhouse gas (GHG) emissions are at particular risk of involuntary migration and displacement due to climate change, reinforcing the urgency for industrialised countries to continue lowering GHG emissions, to support adaptive capacity-building initiatives under the UNFCCC and to meet objectives expressed in the Global Compacts regarding safe, orderly and regular migration and the support and accommodation of displaced people (Sections 4.3.7, 4.5.7, 5.12.2, 7.4.5.5, 8.4.2; Box 8.1; Cross-Chapter Box SLR in Chapter 3).

<div id="box-7.4" class="h2-container box-container"></div>

'''Box 7.4 | Gender Dimensions of Climate-Related Migration'''
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Migration decision-making and outcomes—in both general terms and in response to climatic risks—are strongly mediated by gender, social context, power dynamics and human capital ( [[#Bhagat--2017|Bhagat, 2017]] ; [[#Singh--2020|Singh and Basu, 2020]] ; [[#Rao--2019a|Rao et al., 2019a]] ; [[#Ravera--2016|Ravera et al., 2016]] ). Women tend to suffer disproportionately from the negative impacts of extreme climate events for reasons ranging from caregiving responsibilities to lack of control over household resources to cultural norms for attire ( [[#Belay--2017|Belay et al., 2017]] ; [[#Jost--2016|Jost et al., 2016]] ). In many cultures, migrants are most often able-bodied, young men ( [[#Call--2017|Call et al., 2017]] ; [[#Heaney--2016|Heaney and Winter, 2016]] ). Women wait longer to migrate because of higher social costs and risks ( [[#Evertsen--2019|Evertsen and Van Der Geest, 2019]] ) and barriers such as social structures, cultural practices, lack of education and reproductive roles ( [[#Belay--2017|Belay et al., 2017]] ; [[#Afriyie--2018|Afriyie et al., 2018]] ; [[#Evertsen--2019|Evertsen and Van Der Geest, 2019]] ).

Research critiques the tendency to portray women as victims of climate hazards rather than recognising differences between women and the potential for women to use their agency and informal networks to negotiate their situations ( [[#Eriksen--2015|Eriksen et al., 2015]] ; [[#Ngigi--2017|Ngigi et al., 2017]] ; [[#Pollard--2015|Pollard et al., 2015]] ; [[#Rao--2019b|Rao et al., 2019b]] ; [[#Ravera--2016|Ravera et al., 2016]] ). Migration can change household composition and structure, which in turn affects the adaptive capacity and choices of those who do not move ( [[#Rao--2019a|Rao et al., 2019a]] ; [[#Rao--2019b|Rao et al., 2019b]] ; [[#Singh--2019|Singh, 2019]] ). For example, when only male household members move, the remaining members of the now female-headed household must take on greater workloads ( [[#Goodrich--2019|Goodrich et al., 2019]] ; [[#Rao--2019b|Rao et al., 2019b]] ; [[#Rigg--2015|Rigg and Salamanca, 2015]] ), leading to increased workload and greater vulnerability for those left behind ( [[#Arora--2017|Arora et al., 2017]] ; [[#Bhagat--2017|Bhagat, 2017]] ; [[#Flatø--2017|Flatø et al., 2017]] ; [[#Lawson--2019|Lawson et al., 2019]] ). It can, however, also increase women’s economic freedom and decision-making capacity, enhance their agency ( [[#Djoudi--2016|Djoudi et al., 2016]] ; [[#Rao--2019|Rao, 2019]] ) and alter the gendered division of paid work, care and intra-household relations ( [[#Rigg--2018|Rigg et al., 2018]] ; [[#Singh--2020|Singh and Basu, 2020]] ), a process that may reduce household vulnerability to extreme climate events ( [[#Banerjee--2019b|Banerjee et al., 2019b]] ).

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