Editing IPCC:AR6/WGII/Chapter-16 (section)

===== 16.5.2.3.8 Risks to peace and to human mobility (RKR-H) =====

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This RKR includes risks to peace within and among societies from armed conflict as well as risks to human mobility, epitomised by involuntary migration and displacement within and across state borders and involuntary immobility. Breakdown of peace and the inability of people to choose to move or stay challenge core elements of human security ( [[#Adger--2014|Adger et al., 2014]] ). Risks to peace also inform the agency and viability of mobility decisions. However, evidence does not indicate that human mobility constitutes a general risk to peace.

Breakdown of peace, materialised as overt or covert violence across social and spatial scales, constitutes a key risk because of its potential to cause widespread loss of life, livelihood and well-being. Such impacts are considered severe if they result in at least 1000 excess battle-related deaths in a country in a year. This threshold is consistent with the conventional definition of war ( [[#Pettersson--2020|Pettersson and Öberg, 2020]] ). However, because armed conflict routinely causes significant material destruction, triggers mass displacement, threatens health and food security, and undermines economic activity and living standards ( [[#Baumann--2016|Baumann and Kuemmerle, 2016]] ; [[#FAO--2017|FAO et al., 2017]] ; [[#de%20Waal--2018|de Waal, 2018]] ), risks to peace can be considered severe also when conflict has cascading effects on other aspects of well-being and amplifies vulnerability to other RKRs. Beyond the magnitude of such impacts, the rapidity with which armed conflict can escalate and the challenges of ending violence once it has broken out imply potentially very limited time and ability to respond for populations at risk.

Mobility is a universal strategy for pursuing well-being and managing household risks ( [[IPCC:Wg2:Chapter:Chapter-7#7.2.6|Section 7.2.6]] ; Cross-Chapter Box MIGRATE in Chapter 7, [[#UN--2018|UN, 2018]] ) and, where it occurs in a safe and orderly fashion, can reduce social inequality and facilitate sustainable development (Franco [[#Gavonel--2021|Gavonel et al., 2021]] ). Involuntary mobility constitutes a key risk because it implies reduced human agency with high potential for significant economic losses and non-material costs, an unequal gender burden, and amplified vulnerability to other RKRs ( [[#Schwerdtle--2018|Schwerdtle et al., 2018]] ; [[#Adger--2020|Adger et al., 2020]] ; [[#Maharjan--2020|Maharjan et al., 2020]] ; [[#Piggott-McKellar--2020|Piggott-McKellar et al., 2020]] ). Climate change also may erode or overwhelm human capacity to use mobility as a coping strategy, producing involuntarily immobile populations ( [[#Adams--2016|Adams, 2016]] ). A severe impact is when a large share of an affected population is forcibly displaced or prevented from moving, relative to normal mobility patterns, at local to global scale. However, because mobility may be a favourable mechanism for reducing risk or an adverse outcome of risk, depending on the circumstances under which it occurs, it is not possible to specify a simple quantitative threshold for when impacts become severe.

Complex causal pathways and lack of long-term projection studies presently prevent making confident quantitative judgements about how risks to peace and human mobility will materialise in response to specific warming levels, development pathways and adaptation scenarios. Literature concludes with ''medium confidence'' that risks to peace will increase with warming, with the largest impacts expected in weather-sensitive communities with low resilience to climate extremes and high prevalence of underlying risk factors ( [[#Theisen--2017|Theisen, 2017]] ; [[#Busby--2018|Busby, 2018]] ; [[#Koubi--2019|Koubi, 2019]] ; [[#von%20Uexkull--2021|von Uexkull and Buhaug, 2021]] ). However, climate-driven impacts on societies will depend critically on future political and socioeconomic development trajectories ( ''limited evidence'' , ''high agreement'' ), suggesting that risks due to climate change are relevant primarily for highly vulnerable populations and for pessimistic development scenarios. Overall risks to peace may decline despite warming if non-climatic determinants are reduced sufficiently in the future.

Regular human mobility will continue regardless of climate change, but mobility-related risks will increase with warming, notably in densely populated hazard-prone regions, in small islands and low-lying coastal zones, and among populations with limited coping capacity (RKR-A; Section [https://www.ipcc.ch/chapter/16#CCP2.2 CCP2.2.2] ; Chapter 7) ( ''high confidence'' ). Such risks can become severe even with limited levels of warming for populations with low adaptive capacity and whose settlements and livelihoods are critically sensitive to environmental conditions ( ''medium evidence'' , ''high agreement'' ). Likewise, risk of involuntary immobility could become severe for highly vulnerable populations with limited resources, even with moderate levels of warming ( ''limited evidence'' , ''high agreement'' ). Critically, population growth and shifting exposure will interact with warming to shape these risks ( [[#Davis--2018|Davis et al., 2018]] ; [[#Hauer--2020|Hauer et al., 2020]] ; [[#Robinson--2020a|Robinson, 2020a]] ). Although climate-driven human mobility generally does not increase risks to peace ( ''medium confidence'' ), armed conflict is a major driver of forced displacement ( ''high confidence'' ).

Expert elicitation estimates that 4°C warming above pre-industrial levels will have severe and widespread effects on armed conflict with 26% probability, assuming no change from present levels in non-climatic drivers ( [[#Mach--2019|Mach et al., 2019]] ). That judgement refers to impacts that exceed the threshold for severity considered here, suggesting that global warming of 4°C would produce severe risks to peace under present societal conditions ( ''low confidence'' ). Future risks to peace will remain strongly influenced by socioeconomic development ( [[#Hegre--2016|Hegre et al., 2016]] ). A study of Sub-Saharan Africa that accounts for both temperature and socioeconomic changes, 2015–2065, concludes that determinants other than rising temperatures, notably quality of governance, will remain most influential in shaping overall levels of violence even in the high-warming RCP8.5 scenario ( [[#Witmer--2017|Witmer et al., 2017]] ).

A larger empirical literature offers indirect evidence that climate change may produce severe risks to peace within this century by demonstrating how climate variability and extremes affect contemporary conflict dynamics, especially in contexts marked by low economic development, high economic dependence on climate-sensitive activities, high or increasing social marginalisation, and fragile governance ( ''medium confidence'' ) (Sections 7.2.7, 16.2, [[#Schleussner--2016a|Schleussner et al., 2016a]] ; [[#Von%20Uexkull--2016|Von Uexkull et al., 2016]] ; [[#Busby--2018|Busby, 2018]] ; [[#Harari--2018|Harari and Ferrara, 2018]] ; [[#Ide--2020|Ide et al., 2020]] ; [[#Scartozzi--2020|Scartozzi, 2020]] ).

Climatic risks interact with economic, political and social drivers to create risks to human mobility both directly (through the threat of physical harm and destruction of property and infrastructure) and indirectly (via adverse impacts on livelihood and well-being). Extreme weather events are leading causes of forced displacement (Cross-Chapter Box MIGRATE in Chapter 7, [[#IDMC--2020|IDMC, 2020]] ). Projected increases in the frequency and severity of extreme events ( [[#Ranasinghe--2021|Ranasinghe et al., 2021]] ) in combination with future population growth in hazard-prone regions (e.g., [[#Merkens--2016|Merkens et al., 2016]] ) suggest that risks to mobility will increase in response to future global warming ( [[#Robalino--2015|Robalino et al., 2015]] ; [[#Davis--2018|Davis et al., 2018]] ; [[#Rigaud--2018|Rigaud et al., 2018]] ). For example, moving from RCP2.6 to RCP8.5 (entailing ~0.5°C additional global warming by 2050) is projected to increase internal migration by 2050 from 51 [31–72] million to 118 [92–143] million people across South Asia, Latin America and Africa ( [[#Rigaud--2018|Rigaud et al., 2018]] ), although those estimates principally comprise migrants, whose decisions are also informed by non-climatic drivers, rather than involuntarily displaced people. Global levels of flood displacement are estimated to increase by 50% with each 1°C warming ( [[#Kam--2021|Kam et al., 2021]] ). Should future warming reduce adaptation options for vulnerable populations ( [[#16.4|Section 16.4]] ), a consequence may be higher levels of involuntary migration and immobility ( [[#Grecequet--2017|Grecequet et al., 2017]] ; [[#Otto--2017|Otto et al., 2017]] ). There is little evidence that climate-driven mobility negatively affects peace ( [[#Brzoska--2016|Brzoska and]] [[#Fröhlich--2016|Fröhlich, 2016]] ; [[#Burrows--2016|Burrows and Kinney, 2016]] ; [[#Freeman--2017|Freeman, 2017]] ; [[#Petrova--2021|Petrova, 2021]] ).

There is ''high agreement'' that even moderate levels of future SLR will severely amplify involuntary migration and displacement in small islands and densely populated low-lying coastal areas in the absence of appropriate adaptive responses ( ''high confidence'' ) ( [[#Hauer--2017|Hauer, 2017]] ; [[#IPCC--2019b|IPCC, 2019b]] ; [[#Hauer--2020|Hauer et al., 2020]] ; [[#McMichael--2020|McMichael et al., 2020]] , Sections 15.3.4, 16.4). In some contexts, climate change also may accelerate migration towards high-exposure coastal areas ( [[#Bell--2021|Bell et al., 2021]] ). Under a high-emissions RCP8.5 scenario (global median 0.7 m SLR by 2100), the number of people exposed to annual coastal flooding may more than double by 2100 compared with present numbers ( [[#Kulp--2019|Kulp and Strauss, 2019]] ). In the USA alone, SLR of 0.9 m could potentially put 4.2 million people at risk of inundation by the end of this century ( [[#Hauer--2017|Hauer, 2017]] ). However, number of people exposed to SLR does not evenly translate to forcibly displaced populations ( [[#Hauer--2020|Hauer et al., 2020]] ). Ascertaining how many people will move forcibly or as an adaptive response to SLR is inherently challenging because of the complex and highly individual nature of migration decisions ( [[#Black--2013|Black et al., 2013]] ; [[#Boas--2019|Boas et al., 2019]] ; [[#Piguet--2019|Piguet, 2019]] ; [[#Bell--2021|Bell et al., 2021]] ). Implications of climate change for risks to human mobility across borders are even harder to quantify and highly uncertain, due to unknown developments in legal and political conditions that govern international migration ( [[#McLeman--2019|McLeman, 2019]] ; [[#Wrathall--2019|Wrathall et al., 2019]] ).

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