Editing IPCC:AR6/WGII/Chapter-17 (section)

=== 17.2.1 Adaptation Options for Climate Risk Management ===

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This section assesses options for climate risk management (CRM) across common risk settings that have been grouped into Representative Key Risks (RKRs; see [[IPCC:Wg2:Chapter:Chapter-16#16.5.2.2|Section 16.5.2.2]] ). These risk management and adaptation actions target the components of risk: hazards, vulnerabilities and exposure associated with sudden or slow-onset events (see [[IPCC:Wg2:Chapter:Chapter-1|Chapter 1]] for more details on the definition of risk).

For each of the RKRs, three commonly discussed adaptation options are identified across the regional, sectoral and cross-chapter papers of this report. These 24 options have been selected to cover a representative variety of strategies to adapt to climate change, while a particular adaptation option can be relevant to many of the RKRs. For example, the adaptations listed under the RKR of ‘Food security’ are also related to the RKR on ‘Human health’ ( [[#Ebi--2015|Ebi and Prats, 2015]] ). See SM17.1 for more detail. The list is not comprehensive of all possible adaptations listed in the regional and sectoral chapters. For example, this does not include adaptations by institutions who might become unable to cope with increasing pace and magnitude of extreme events (Chapter 11).

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==== 17.2.1.1 Adaptation Options and Their Contribution to Reduce Vulnerability and Exposure ====

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Table 17.1 provides examples of each of these 24 adaptation options from across AR6 WGII. Detailed information about sectors and regions where these adaptations are being discussed can be found in the indicated chapters. Note that this list is curated to ensure a diversity of options; therefore, most of the options will apply to more than one RKR.

Of this list of adaptation options, many focus on reducing vulnerability to climate change ( ''high confidence'' ), as vulnerability is one of the components of risk (see [[IPCC:Wg2:Chapter:Chapter-1|Chapter 1]] and Chapter 8). Vulnerability is the propensity or predisposition to be adversely affected, including sensitivity or susceptibility to harm and lack of capacity to cope and adapt (see [[IPCC:Wg2:Chapter:Chapter-1|Chapter 1]] for more details). In the world’s threatened ecosystems, reducing vulnerability often means reducing other non-climate negative pressures on ecosystems, such as pesticide use or fishery overexploitation ( [[IPCC:Wg2:Chapter:Chapter-3#3.3|Section 3.3]] ).

Vulnerability reduction is also a major focus in human systems, and this includes development of investments that help people adapt to climate change. Examples include irrigation or diversifying crops. Building infrastructure resilient to climate-related risks is another example; many of the structural and physical adaptation options can reduce sensitivity to disasters, such as elevating houses or doing beach nourishment in coastal areas ( [[IPCC:Wg2:Chapter:Chapter-15#15.5|Section 15.5]] ). Extreme events often catalyse investment in adaptation to reduce vulnerability for the future ( [[#Kreibich--2017|Kreibich et al., 2017]] ; [[#Slavíková--2021|Slavíková et al., 2021]] ).

Next to vulnerability reduction, a large number of adaptation options focus on reducing exposure to climate change ( ''high confidence'' ). Selecting low-risk locations is the most basic example of reducing exposure; for example, private companies are relocating factories to reduce flood-related disruptions to their supply chain ( [[#Neise--2019|Neise and Revilla Diez, 2019]] ), and species are autonomously adjusting their ranges to a changing climate ( [[IPCC:Wg2:Chapter:Chapter-2#2.4|Section 2.4]] ). Land use planning or investing in resilient infrastructure can avoid exposure in rapidly urbanising areas; however, the design and enforcement of these regulations can negatively impact marginalised people ( [[#Anguelovski--2016|Anguelovski et al., 2016]] ).

Managed retreat is an example of exposure reduction that, while often controversial, is increasingly being considered and implemented (CCP 2.2.2, [[IPCC:Wg2:Chapter:Chapter-15#15.3.4|Section 15.3.4]] ; Cross-Chapter Box LOSS in this Chapter; [[#Siders--2019|Siders et al., 2019]] ). Examples include the US Hazard Mitigation Grant Program, which, among other activities, has helped people resettle outside of flood zones, and a ‘no-build zone’ established in the Philippines after Typhoon Haiyan ( [[#Hino--2017|Hino et al., 2017]] ). However, relocation is not always an option; immobility is sometimes involuntary, such as in the case of ‘trapped’ populations in Zambia ( [[#Nawrotzki--2018|Nawrotzki and DeWaard, 2018]] ; [[IPCC:Wg2:Chapter:Chapter-8#8.2.1|Section 8.2.1.3]] ).

Adaptation efforts can have negative impacts on ecosystems and vulnerable groups ( ''high confidence'' ); see Figure 17.3 and [[#17.5|Section 17.5]] for further information on maladaptation. While ‘hard’ structural investments have been popular to reduce exposure to climate extremes, barrier-type measures provide protection only up to a certain limit, and are designed to fail in more extreme events. Given the risk of catastrophe from a climate extreme overcoming a physical barrier, policy advancements in recent years encourage any investment in structural measures to be complemented by ‘softer’ vulnerability reduction measures, such as accommodating building construction ( [[#Wesselink--2016|Wesselink, 2016]] ).

When it comes to ‘softer’ vulnerability reduction initiatives, these were traditionally seen as ‘no regrets’ options for adaptation. However, subsequent studies have cautioned that notion as vulnerability is a dynamic quality, and can be co-created while development or adaptation efforts are being implemented ( [[#Schipper--2006|Schipper and Pelling, 2006]] ; [[#Tempels--2014|Tempels and Hartmann, 2014]] ; [[#Dilling--2015|Dilling et al., 2015]] ). Some scholars have suggested the application of a ‘do no harm’ principle to climate change adaptation efforts ( [[#Mayer--2016|Mayer, 2016]] ).

'''Table 17.1 |''' Selected adaptation options per Representative Key Risk (RKR; see [[IPCC:Wg2:Chapter:Chapter-16#16.5.2.2|Section 16.5.2.2]] ), with examples of each option from across the report. Many of the adaptation options are relevant to multiple RKRs, and have been selected to be representative of the wide variety of adaptation options implemented or suggested around the world.

{| class="wikitable"
|-
! RKR

! Adaptation option

! Examples from regional and sectoral chapters and cross-chapter papers

|-
| rowspan="3"| Risk to coastal socio-ecological systems

| Coastal accommodation

| Raising of dwellings, raising of coastal roads ( [[IPCC:Wg2:Chapter:Chapter-15#15.5.2|Section 15.5.2]] ), amphibious building designs (CCP2), improved drainage ( [[IPCC:Wg2:Chapter:Chapter-11#11.3.5.3|Section 11.3.5.3]] )

|-
| Coastal infrastructure

| Seawalls, beach and shore nourishment (Sections 3.6, 15.5.1), breakwater structures ( [[IPCC:Wg2:Chapter:Chapter-15#15.5.1|Section 15.5.1]] ), dykes, revetments, groynes or tidal barriers. ( [[IPCC:Wg2:Chapter:Chapter-6#6.3.4|Section 6.3.4.8]] ), land reclamation ( [[IPCC:Wg2:Chapter:Chapter-15#15.5.2|Section 15.5.2]] )

|-
| Strategic coastal retreat

| Retreating from coastal areas ( [[IPCC:Wg2:Chapter:Chapter-3#3.6|Section 3.6]] , Cross-Chapter Box SLR in Chapter 3, [[IPCC:Wg2:Chapter:Chapter-6#6.3.5.1|Section 6.3.5.1]] , CCP2), relocation/resettlement (CCP2)

|-
| rowspan="3"| Risk to terrestrial and ocean ecosystems

| Restore/create natural areas

| Marine protected areas (FAQ 3.5), active restoration of coral reefs ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.2.3|Section 3.6.2.3.2]] ), ridge-to-reef management (CCP1), restoring dunes (CCP4), planting salinity-tolerant trees ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] )

Increasing forest cover (CCP7), detect and manage forest pests ( [[IPCC:Wg2:Chapter:Chapter-11#11.3.4.3|Section 11.3.4.3]] )

|-
| Reduce ecosystem stress

| Reduce pollution and eutrophication ( [[IPCC:Wg2:Chapter:Chapter-3#3.3.3|Section 3.3.3]] ), reduce anthropogenic pressures on the Great Barrier Reef (Box 11.2), sustainable fisheries harvest ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.2|Section 3.6.2]] ), increasing connectivity between natural areas ( [[IPCC:Wg2:Chapter:Chapter-2#2.6.2|Section 2.6.2]] )

|-
| Ecosystem-based adaptation

| Marine habitats to protect against storm surge ( [[IPCC:Wg2:Chapter:Chapter-3#3.6|Section 3.6]] ), agroecology ( [[IPCC:Wg2:Chapter:Chapter-5#5.1|Section 5.1]] 4.1.1), coastal and marine vegetation and reefs ( [[IPCC:Wg2:Chapter:Chapter-6#6.3.3.4|Section 6.3.3.4]] ), vegetation corridors, greenspace, wetlands (FAQ 6.3), mangrove habitat restoration (Sections 8.5.2.2, 9.8.5.1), restoring coasts, rivers, wetlands to reduce flood risk ( [[IPCC:Wg2:Chapter:Chapter-2#2.6.3|Section 2.6.3]] , CCP1), urban green space to reduce temperatures ( [[IPCC:Wg2:Chapter:Chapter-2#2.6.3|Section 2.6.3]] )

|-
| rowspan="3"| Risks associated with critical physical infrastructure, networks and services

| Infrastructure retrofitting

| Air conditioning ( [[IPCC:Wg2:Chapter:Chapter-6#6.3.4|Section 6.3.4]] ), using thermosiphons for permafrost degradation ( [[IPCC:Wg2:Chapter:Chapter-10#10.4.6.4.1|Section 10.4.6.4.1]] ), increasing rooftop albedo (for reflectivity) ( [[IPCC:Wg2:Chapter:Chapter-11#11.3.5.3|Section 11.3.5.3]] ), shading (Section 13.A.4)

|-
| Building codes

| Drainage systems ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] ), architectural and urban design regulations ( [[IPCC:Wg2:Chapter:Chapter-6#6.3.4.2|Section 6.3.4.2]] ), infrastructure standards initiatives (CCP6), Chile’s Sustainable Housing Construction Code ( [[IPCC:Wg2:Chapter:Chapter-12#12.5.5.3|Section 12.5.5.3]] )

|-
| Spatially redirect development

| Zoning/land use planning ( [[IPCC:Wg2:Chapter:Chapter-6#6.3.2|Section 6.3.2.1]] ), spatial development planning to regulate coastal development (CCP2)

|-
| rowspan="3"| Risk to living standards and equity

| Insurance

| Agricultural insurance and micro-credit (Sections 4.5.2.1, 10.4.5.5), index-based insurance, market and price insurance ( [[IPCC:Wg2:Chapter:Chapter-5#5.1|Section 5.1]] 4.1.3), flood insurance ( [[IPCC:Wg2:Chapter:Chapter-10#10.5.3.2|Section 10.5.3.2]] ), collective insurance schemes ( [[IPCC:Wg2:Chapter:Chapter-12#12.5.7|Section 12.5.7.5]] )

|-
| Diversification of livelihoods

| Combining income-generating activities within fisheries sector ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.2.2|Section 3.6.2.2]] )

Community level adaptation by Pangnirtung Inuit through diversification to stabilise income and food resources (CCP6)

|-
| Social safety nets

| Food for work programmes ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] ), school feeding programmes ( [[IPCC:Wg2:Chapter:Chapter-7#7.4.2.1|Section 7.4.2.1.3]] ), social protection programmes, such as unemployment compensation ( [[IPCC:Wg2:Chapter:Chapter-10#10.5.6|Section 10.5.6]] )

|-
| rowspan="3"| Risk to human health

| Availability of health infrastructure

| Safe drinking water infrastructure ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] ), temperature-controlled low-income housing ( [[IPCC:Wg2:Chapter:Chapter-11#11.3.6.3|Section 11.3.6.3]] ), health care clinics ( [[IPCC:Wg2:Chapter:Chapter-6#6.4|Section 6.4]] case study), place-specific mental health infrastructure and ‘nature therapy’ ( [[IPCC:Wg2:Chapter:Chapter-14#14.4|Section 14.4.6.8]] )

|-
| Access to health care

| Access to health care services ( [[IPCC:Wg2:Chapter:Chapter-11#11.3.6.3|Section 11.3.6.3]] ), access to health, nutrition services and healthy environments (water and sanitation) (Section 7.6), enhanced access to culturally appropriate mental health resources; ‘Telemedicine’ (information technologies and telecommunications for health and public health service delivery) ( [[IPCC:Wg2:Chapter:Chapter-12#12.6.1|Section 12.6.1.5]] )

|-
| Disaster early warning

| Early warning of marine heatwaves ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.2.3|Section 3.6.2.3.3]] ) early warning for pests ( [[IPCC:Wg2:Chapter:Chapter-5#5.12.5|Section 5.12.5]] ), Heat Action Plans (HAP) ( [[IPCC:Wg2:Chapter:Chapter-7#7.4.2.1|Section 7.4.2.1.2]] ), raising public awareness through campaigns (FAQ13.3)

|-
| rowspan="3"| Risk to food security

| Farm/fishery improvements

| Changing fishing gear or vessel power ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.2.2|Section 3.6.2.2.3]] ), change crop variety or timing ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] , CCP5, [[IPCC:Wg2:Chapter:Chapter-8#8.5|Section 8.5]] ), close productivity gaps ( [[IPCC:Wg2:Chapter:Chapter-5#5.12.5|Section 5.12.5]] ), biotechnology ( [[IPCC:Wg2:Chapter:Chapter-5#5.12.5|Section 5.12.5]] ), irrigation schemes ( [[IPCC:Wg2:Chapter:Chapter-9#9.12|Section 9.12.5.3]] ), integrated crop/livestock systems ( [[IPCC:Wg2:Chapter:Chapter-5#5.10.1|Section 5.10.1]] ), relocating livestock linked to improved pasture management ( [[IPCC:Wg2:Chapter:Chapter-13#13.5.2|Section 13.5.2]] )

|-
| Food storage/distribution improvements

| Improve transportation infrastructure and trade networks, shortened supply chains (Sections 5.12.5, 9.12.5.3), improved food storage (Sections 5.12.5, 7.4.2), local food production/chains (Cross-Chapter Box COVID in Chapter 7)

|-
| Behaviour change in diets and food waste

| Reduce food loss and waste ( [[IPCC:Wg2:Chapter:Chapter-5#5.12.5|Section 5.12.5]] ), shifts to more plant-based diets ( [[IPCC:Wg2:Chapter:Chapter-7#7.4.5.2|Section 7.4.5.2]] ), creating demand for organically sourced food ( [[IPCC:Wg2:Chapter:Chapter-10#10.5.3.2|Section 10.5.3.2]] )

|-
| rowspan="3"| Risk to water security

| Water capture/storage

| Farm ponds and revival of water bodies ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] ), rain gardens, bioswales or retention ponds ( [[IPCC:Wg2:Chapter:Chapter-6#6.3.3.6|Section 6.3.3.6]] ), water storage tanks ( [[IPCC:Wg2:Chapter:Chapter-10#10.5.3.2|Section 10.5.3.2]] ), multi-purpose water reservoirs and dams (CCP5)

|-
| Efficient water use/demand

| Precision/drip irrigation ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] ), Managed Aquifer Recharge (MAR) ( [[IPCC:Wg2:Chapter:Chapter-9#9.4|Section 9.4]] ), cooperative policies across multiple sectors (CCP4), changing water consumption patterns (CCP4)

|-
| Efficient water supply/distribution

| Constructing irrigation infrastructure ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] ), inter-basin transfers ( [[IPCC:Wg2:Chapter:Chapter-6#6.3.3.6|Section 6.3.3.6]] ), water reuse (Section 13.A.3), slum/water upgrading ( [[IPCC:Wg2:Chapter:Chapter-6#6.4.3|Section 6.4.3]] )

|-
| rowspan="3"| Risk to peace and migration

| Seasonal/temporary mobility

| Fishing fleet mobility to follow species distribution ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.2.2|Section 3.6.2.2.2]] ), mobility for seasonal employment and remittances ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] , Cross-Chapter Box MIGRATE in Chapter 7), legal/illegal labour migration (CCP3), pastoralist seasonal migrations (Cross-Chapter Box MIGRATE in Chapter 7)

|-
| Cooperative governance

| Transboundary fishing agreements ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.4.1|Section 3.6.4.1]] ), ocean governance ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.2.2|Section 3.6.2.2]] ), collective water management ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] ), indigenous water-sharing systems ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] ), enforcing the land rights of indigenous populations (CCP7), adaptive co-management in Arctic fisheries (CCP6), international compact on migration (Cross-Chapter Box MIGRATE in Chapter 7), policies for adaptive governance ( [[IPCC:Wg2:Chapter:Chapter-8#8.5|Section 8.5]] )

|-
| Permanent migration

| Resettlement of flood-prone communities ( [[IPCC:Wg2:Chapter:Chapter-4#4.5.2|Section 4.5.2.1]] ), rural–urban migration ( [[IPCC:Wg2:Chapter:Chapter-6#6.1|Section 6.1]] case study), internal migration (Box 10.2), international migration and remittances (Sections 8.6.3, 14.4.7.3)

|}

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==== 17.2.1.2 Governance of Adaptation Options ====

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For each adaptation option identified for the RKRs (Table 17.1), this section presents an assessment of how decisions are made and how the adaptations are being governed. The following section then covers benefits to humans and ecosystems, and potential for maladaptation is covered in [[#17.5|Section 17.5]] . See SM17.1 for more information on the assessment methods and underlying citations.

The following analysis of adaptation options provides a synthesised overview of adaptation globally, but does not prescribe how important each adaptation should be in specific locations. [[IPCC:Wg2:Chapter:Chapter-16|Chapter 16]] finds that the ‘scope’ and ‘speed’ of adaptation is limited in many areas.

When it comes to decision-making, most of these 24 adaptations rely strongly on formal decision-making ( ''high confidence'' ), which follows the procedures of a group of people rather than ad hoc individual action. Formal decisions play a particularly strong role in the adaptations identified for infrastructure, early-warning systems and water systems ( [[#Kolen--2014|Kolen and Helsloot, 2014]] ; [[#Calvello--2015|Calvello et al., 2015]] ; [[#Zhao--2017|Zhao et al., 2017]] ; [[#Belčáková--2019|Belčáková et al., 2019]] ; [[#Teo--2019|Teo et al., 2019]] ).

In contrast, informal or individual-led decision-making is more common in several food security-related and livelihood-related adaptations, such as changes to diets, livelihood diversification and seasonal migration ( ''high confidence'' ) ( [[#Li--2017|Li et al., 2017]] ; [[#Radel--2018|Radel et al., 2018]] ; [[#Robinson--2020|Robinson et al., 2020]] ). People who have experienced climate shocks are more likely to take individual decisions to implement adaptation measures, and in countries where people are more exposed to extreme events, autonomous adaptation is more common ( [[#Koerth--2017|Koerth et al., 2017]] ; [[#Aerts--2018b|Aerts et al., 2018b]] ; [[#van%20Valkengoed--2019|van Valkengoed and Steg, 2019]] ).

All adaptation options can occur under a range of governance arrangements ( ''high confidence'' ), with cases of either private, public or community governance typically playing the dominant role, as depicted in Figure 17.2. Public governance is the most frequent governance type for most adaptations considered. This is particularly true for social safety nets and spatial planning, where governments are often required to lead adaptation efforts ( ''high confidence'' ) ( [[#Mesquita--2016|Mesquita and Bursztyn, 2016]] ; [[#Hssaisoune--2020|Hssaisoune et al., 2020]] ; [[#Wang--2021|Wang et al., 2021]] ). While government actors do the day-to-day management of these systems, civil society and international organisations also play a role in shaping agendas and priorities of government actors ( [[#Nagle%20Alverio--2021|Nagle Alverio et al., 2021]] ).

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[[File:571c4f480731825e8124cd58a563fa9c IPCC_AR6_WGII_Figure_17_002.png]]

'''Figure 17.2 |''' '''Governance of 24 major risk management options, grouped by relevance to the Representative Key Risks.''' Each option depicts the relative governance roles, between communities/individuals, private sector and public sector. The intensity of the colour refers to the level of confidence in the assessment.

The private sector plays a large role in governance of insurance, minimising ecosystem stressors, and livelihood diversification ( ''medium confidence'' ) ( [[#Allen--2018|Allen et al., 2018]] ; [[#Mimet--2020|Mimet et al., 2020]] ; [[#Alam--2020a|Alam et al., 2020a]] ). While having a key role in shaping and implementing many other adaptations, the private sector is not often the governing entity.

There are a number of adaptation options that tend to be governed by communities and individuals, including adaptations to farming and fishery practices and ecosystem-based adaptations ( ''high confidence'' ) ( [[#Reid--2016|Reid, 2016]] ; [[#Basupi--2019|Basupi et al., 2019]] ; [[#Giffin--2020|Giffin et al., 2020]] ; [[#Karlsson--2020|Karlsson and Mclean, 2020]] ). In rapidly urbanising areas of Asia and Africa, individual- or community-led adaptation is the norm in informal settlements that have poor governance structures. Residents of Mathare slum in Nairobi have established methods to pool risks, such as pooling labour to police looting during flood events and developing community health centres in churches ( [[#Thorn--2015|Thorn et al., 2015]] ). This is in addition to risk reduction measures such as building structures to withstand rising water levels ( [[#Thorn--2015|Thorn et al., 2015]] ). Residents in Bangkok have built walls around settlements, dug informal drainage channels to vacant lots, and filled areas of land ( [[#Limthongsakul--2017|Limthongsakul et al., 2017]] ). In these cases, individual-led adaptation can have negative side effects, such as the building of flood defences in affluent communities increasing the flood impacts in less affluent regions of a city ( [[#Limthongsakul--2017|Limthongsakul et al., 2017]] ).

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==== 17.2.1.3 Benefit to Humans and Ecosystems ====

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While some of the 24 adaptation options are specific to certain risk contexts (e.g., coastal areas, agricultural production), others are more widely applicable (e.g., early-warning systems, health care systems, creation/restoration of natural areas). Figure 17.3 depicts which of these are most context specific, for example benefitting less than 1 billion people. This is contrasted with the extent to which each adaptation option is beneficial to ecosystem services. Many of the more generalisable adaptations have also been shown to have benefits to ecosystem services, such as nature restoration and changes to diets/food waste ( ''medium confidence'' ). While health care systems and the establishment of health-related infrastructure can be widely used as adaptation options, their design and application to date have not generally benefitted ecosystems or ecosystem services ( ''medium evidence'' , ''low agreement'' ).

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[[File:39c55a30d83a82aece7d2e7058e6a0f8 IPCC_AR6_WGII_Figure_17_003.png]]

'''Figure 17.3 |''' '''Benefit of representative adaptation options to humans and ecosystems.''' The breadth of applicability of each adaptation option benefiting humans is estimated by the degree to which each adaptation can be applied across multiple contexts, depicted on the x axis. The benefit of each adaptation option for ecosystems and ecosystem services is depicted on the y axis. See Annex A for literature underpinning each assessment. This figure uses the 24 representative adaptation options from Table 17.1 and Figure 17.2. Confidence levels are represented by dots.

As a general method related to adaptive management, ‘early warnings’ are the most frequently discussed adaptation option to deal with a changing climate across all key risks, sectors and regions. Early-warning systems are an adaptation that can benefit more than 5 billion people ( ''high confidence'' ). Examples range from short-term disaster early-warning systems to revision of sea level rise plans based on monitoring. For example, the humanitarian community is investing in forecast-based financing systems to prepare for extreme events ( [[#Coughlan%20de%20Perez--2015|Coughlan de Perez et al., 2015]] ; [[#MacLeod--2021|MacLeod et al., 2021]] ). Forecasts are also used to manage hydropower dams ( [[#Ahmad--2020|Ahmad and Hossain, 2020]] ), to trigger interventions before public health emergencies ( [[IPCC:Wg2:Chapter:Chapter-7#7.4.2|Section 7.4.2]] ) and to alert fishermen of algal blooms in the world’s oceans ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.2.3|Section 3.6.2.3.3]] ). Table 17.2 provides examples of adaptations using early-warning systems that have been used to address each of the key risks.

In addition to immediate investments that reduce vulnerability and exposure, monitoring and early-warning systems allow people to take additional actions when there is an imminent event on the horizon (e.g., temporary evacuation during extreme events rather than permanent migration). This allows for ongoing adaptive decision-making ( [[#Alessa--2016|Alessa et al., 2016]] ; [[#Ebi--2016|Ebi et al., 2016]] ; [[#Barnard--2017|Barnard et al., 2017]] ; [[#Haasnoot--2018|Haasnoot et al., 2018]] ). However, these systems are only cost-effective for forecastable and actionable hazards, and require effective institutional governance ( [[#Wilkinson--2018|Wilkinson et al., 2018]] ; [[#IPCC--2019c|IPCC, 2019c]] ).

'''Table 17.2 |''' Examples of adaptation investments and early-warning system options for adaptive management for each of the key risks in Chapter 16.

{| class="wikitable"
|-
! Key risk

! Adaptive early-warning systems-based measures

|-
| Risk to coastal socio-ecological systems

| Storm surge early warnings ( [[IPCC:Wg2:Chapter:Chapter-15#15.5.7|Section 15.5.7]] )

Early warnings of water-borne disease ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.2.3|Section 3.6.2.3.3]] )

|-
| Risk to terrestrial and ocean ecosystems

| Fishery marine heatwave warnings and mobile fishing equipment ( [[IPCC:Wg2:Chapter:Chapter-3#3.6.2.3|Section 3.6.2.3]] , Chapter 13)

Forecast of shifts and regime changes in ecosystems ( [[#Pace--2015|Pace et al., 2015]] ; [[#Bauch--2016|Bauch et al., 2016]] ; [[#Burthe--2016|Burthe et al., 2016]] ).

|-
| Risks associated with critical physical infrastructure, networks and services

| Early warning for infrastructure and services (Sections 13.2.2.1, 10.4.6.4.1)

|-
| Risk to living standards and equity

| Adaptive social protection systems ( [[#Schwan--2018|Schwan and Yu, 2018]] ; [[#Ulrichs--2019|Ulrichs et al., 2019]] ; [[#Daron--2021|Daron et al., 2021]] ).

|-
| Risk to human health

| Heat health early-warning systems ( [[IPCC:Wg2:Chapter:Chapter-7#7.4.2.1|Section 7.4.2.1.2]] )

Health and disease monitoring and outbreak prediction (Sections 7.4.2.1.1, 12.5.6)

|-
| Risk to food security

| Forecasting rainfall and droughts for seed selection ( [[IPCC:Wg2:Chapter:Chapter-10#10.5.2.2.3|Section 10.5.2.2.3]] )

Food price early warnings ( [[IPCC:Wg2:Chapter:Chapter-7#7.4.2.1|Section 7.4.2.1.3]] )

|-
| Risk to water security

| Early warnings for flood and drought (Sections 4.4.1, 10.5.2.2.3, 15.5.7)

|-
| Risk to peace and migration

| Transboundary flood early warnings ( [[#Tuncok--2015|Tuncok, 2015]] ).

|}

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