Editing IPCC:AR6/WGII/Cross-Chapter-Paper-2 (section)

=== CCP2.3.5 Retreat ===

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Retreat is a strategy to reduce exposure and eventually risks facing coastal C&amp;S by moving people, assets and activities out of coastal hazard zones ( [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ). This includes adaptive migration, involuntary displacement and planned relocation of population and assets from the coast ( [[IPCC:Wg2:Chapter:Chapter-7#7.2.6|Section 7.2.6]] ; Cross-Chapter Box CB-MIGRATE in Chapter 7).

Planned relocation in coastal C&amp;S with high hazard exposure and climate impacts is already occurring and has been increasing in frequency ( ''medium confidence'' ; [[#Hino--2017|Hino et al., 2017]] ; [[#Mortreux--2018|Mortreux et al., 2018]] ), with some small islands purchasing land in other countries to facilitate movement ( [[#Klepp--2018|Klepp, 2018]] ). In the Arctic, the pressure to relocate away from the coast is expected to rise given the interacting effects of permafrost thaw and coastal erosion. Native villages in Alaska are already relocating ( [[#Ristroph--2017|Ristroph, 2017]] ; [[#Ristroph--2019|Ristroph, 2019]] ). Involuntary resettlement may be a secondary effect of large-scale hard coastal protection projects, or inner-city river and canal regulation. In Jakarta, for example, a new giant seawall project involves resettling coastal households along large parts of the coastline ( [[#Garschagen--2018|Garschagen et al., 2018]] ).

Increased migration is to be expected across different climate scenarios, but there is ''limited evidence'' and ''medium agreement'' about the scale of climate-induced migration at the coast ( [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ; Chapter 16, RKR on peace). Planned relocation is expected to rise in C&amp;S in response to SLR and other coastal hazards ( ''high agreement'' , ''medium evidence'' ; [[#Siders--2019|Siders et al., 2019]] ). Relocation has predominantly been reactive to date, but increased attention is being given to pre-emptive resettlement and the potential pathways and necessary governance, finance and institutional arrangements to support this strategy ( [[#Ramm--2018|Ramm et al., 2018]] ; [[#Lawrence--2020|Lawrence et al., 2020]] ; [[#Haasnoot--2021a|Haasnoot et al., 2021a]] ). There is ''limited evidence'' about the costs of planned relocation and retreat more generally ( [[#Oppenheimer--2019|Oppenheimer et al., 2019]] ).

Retreat can effectively reduce exposure of urban residents to coastal hazards and provide opportunity for re-establishment of ecosystem services ( ''very high confidence'' ; [[#Song--2018|Song et al., 2018]] ; [[#Carey--2020|Carey, 2020]] ; [[#Hindsley--2020|Hindsley and Yoskowitz, 2020]] ; [[#Lincke--2020|Lincke et al., 2020]] ; [[#Lincke--2021|Lincke and Hinkel, 2021]] ). But there is ''high confidence'' that it can sever cultural ties to the coast ( [[#Reimann--2018|Reimann et al., 2018]] ) and lead to negative and inequitable socioeconomic effects for resettled communities if not planned and implemented in ways that are inclusive and just and address cultural, place-attachment and livelihood considerations ( [[#Ajibade--2019|Ajibade, 2019]] ; [[#Adger--2020|Adger et al., 2020]] ; [[#Carey--2020|Carey, 2020]] ; [[#Jain--2021|Jain et al., 2021]] ; [[#Johnson--2021|Johnson et al., 2021]] ), as well as the rights and practices of Indigenous People ( [[#Nakashima--2018|Nakashima et al., 2018]] ; [[#Ristroph--2019|Ristroph, 2019]] ; [[#Mohamed%20Shaffril--2020|Mohamed Shaffril et al., 2020]] ). If planned well ahead and aligned with social goals, pathways to managed retreat can achieve positive outcomes and provide opportunities for transformation of coastal C&amp;S ( [[#Haasnoot--2021a|Haasnoot et al., 2021a]] ; [[#Mach--2021|Mach and Siders, 2021]] ). There is ''medium confidence'' that the availability of suitable and affordable land as well as appropriate financing is a major bottleneck for planned relocation ( [[#Alexander--2012|Alexander et al., 2012]] ; [[#Ong--2016|Ong et al., 2016]] ; [[#Hino--2017|Hino et al., 2017]] ; [[#Fisher--2019|Fisher and Goodliffe, 2019]] ; [[#Hanna--2019|Hanna et al., 2019]] ; [[#Buser--2020|Buser, 2020]] ; [[#Doberstein--2020|Doberstein et al., 2020]] ), particularly in very dense mega-urban areas ( [[#Ajibade--2019|Ajibade, 2019]] ) and crowded small islands ( [[#Neise--2019|Neise and Revilla Diez, 2019]] ; [[#Weber--2019|Weber et al., 2019]] ; [[#Kool--2020|Kool et al., 2020]] ; [[#Lincke--2020|Lincke et al., 2020]] ).

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