IPCC:AR6/SROCC/Chapter-4 - Revision history

Laura: /* Supplementary Material */

2026-06-01T08:41:20Z

Supplementary Material

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	To view the Supplementary Material for Chapter 4 click on the image below		To view the Supplementary Material for Chapter 4 click on the image below

	To download the Chapter 4 data files, [https://ipcc-temp.s3.eu-central-1.amazonaws.com/SROCC_Ch04-SM_DataFiles.zip click here] .		To download the Chapter 4 data files, [https://ipcc-temp.s3.eu-central-1.amazonaws.com/SROCC_Ch04-SM_DataFiles.zip click here].

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	[https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/SROCC_Ch04-SM_FINAL.pdf [[File:13eda1d1a8fc41300a246be5bdf751d1 SROCC-Ch4-SM-Cover.jpg]]]		[https://www.ipcc.ch/site/assets/uploads/sites/3/2019/11/SROCC_Ch04-SM_FINAL.pdf [[File:13eda1d1a8fc41300a246be5bdf751d1 SROCC-Ch4-SM-Cover.jpg\|200px]]]

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Laura: /* Box 4.4 Community Based Experiences: Canadian Arctic and Hawkes Bay, New Zealand */

2026-06-01T08:40:53Z

Box 4.4 Community Based Experiences: Canadian Arctic and Hawkes Bay, New Zealand

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	New Zealand is applying tools for decision making under deep uncertainty (Lawrence and Haasnoot, 2017; Lawrence et al., 2019) to address the changing risk and uncertainties related to SLR impacts on coastal settlements. An opportunity arose in 2017 for the Resilience to Nature’s Challenges National Science Challenge, “The Living Edge” research project ([https://resiliencechallenge.nz/edge/ https://resiliencechallenge.nz/edge]), to co-develop a Coastal Hazards Strategy for the Clifton to Tangoio coast in Hawkes Bay, New Zealand. The Strategy, a joint council/ community/ iwi Māori initiative (Kench et al., 2018), planned to use Multi-Criteria Decision Analysis (MCDA) within their decision framework—a static tool in time and space, unsuited for decision making where changing risk and uncertainties exist over long timeframes. The Dynamic Adaptive Policy Pathways (Haasnoot et al., 2013) approach and a modified Real Options Analysis were proposed by the ‘Edge Team’ and integrated with MCDA (Lawrence et al., 2019) in a process comprising a Technical Advisory Group of councils and two community panels of directly affected communities, infrastructure agencies, business, conservation interests, and iwi Māori. Many adaptation options and pathways were assessed for their ability to reduce risk exposure and maintain flexibility for switching pathways over a 100-year timeframe, which is the planning timeframe mandated by the New Zealand Coastal Policy Statement (Minister of Conservation, 2010) with the force of law under the Resource Management Act, 1991. The recently revised New Zealand national coastal hazards and climate change guidance for local government (Bell et al., 2017a) provided context. This novel assessment, engagement and planning approach to the formulation of a Coastal Hazards Strategy was undertaken through a non-statutory planning process. The agreed options and pathways have yet to be implemented through statutory processes that will test the risk tolerance of the wider community. This example illustrates how tailor-made assessment that addresses SLR uncertainty and change by keeping options open and reducing path-dependency, and engagement and planning processes can be initiated with leadership across councils, sectors and stakeholders, before being implemented, thus reducing contestation. Lessons learned include the central role of: leadership, governance and iwi Māori; Local Authority collaboration; taking time to build trust; independent knowledge brokers for credibility; nuanced project leadership and facilitation, enabling a community-based process. The preferred intervention options and pathways have been agreed for implementation. The remaining challenges are to cost the range of actions, decide funding formulae, develop physical and socioeconomic signals and triggers for monitoring changing risk, embed the strategy in statutory plans and practices, and socialise the strategy with the wider public in the context of competing priorities.		New Zealand is applying tools for decision making under deep uncertainty (Lawrence and Haasnoot, 2017; Lawrence et al., 2019) to address the changing risk and uncertainties related to SLR impacts on coastal settlements. An opportunity arose in 2017 for the Resilience to Nature’s Challenges National Science Challenge, “The Living Edge” research project ([https://resiliencechallenge.nz/edge/ https://resiliencechallenge.nz/edge]), to co-develop a Coastal Hazards Strategy for the Clifton to Tangoio coast in Hawkes Bay, New Zealand. The Strategy, a joint council/ community/ iwi Māori initiative (Kench et al., 2018), planned to use Multi-Criteria Decision Analysis (MCDA) within their decision framework—a static tool in time and space, unsuited for decision making where changing risk and uncertainties exist over long timeframes. The Dynamic Adaptive Policy Pathways (Haasnoot et al., 2013) approach and a modified Real Options Analysis were proposed by the ‘Edge Team’ and integrated with MCDA (Lawrence et al., 2019) in a process comprising a Technical Advisory Group of councils and two community panels of directly affected communities, infrastructure agencies, business, conservation interests, and iwi Māori. Many adaptation options and pathways were assessed for their ability to reduce risk exposure and maintain flexibility for switching pathways over a 100-year timeframe, which is the planning timeframe mandated by the New Zealand Coastal Policy Statement (Minister of Conservation, 2010) with the force of law under the Resource Management Act, 1991. The recently revised New Zealand national coastal hazards and climate change guidance for local government (Bell et al., 2017a) provided context. This novel assessment, engagement and planning approach to the formulation of a Coastal Hazards Strategy was undertaken through a non-statutory planning process. The agreed options and pathways have yet to be implemented through statutory processes that will test the risk tolerance of the wider community. This example illustrates how tailor-made assessment that addresses SLR uncertainty and change by keeping options open and reducing path-dependency, and engagement and planning processes can be initiated with leadership across councils, sectors and stakeholders, before being implemented, thus reducing contestation. Lessons learned include the central role of: leadership, governance and iwi Māori; Local Authority collaboration; taking time to build trust; independent knowledge brokers for credibility; nuanced project leadership and facilitation, enabling a community-based process. The preferred intervention options and pathways have been agreed for implementation. The remaining challenges are to cost the range of actions, decide funding formulae, develop physical and socioeconomic signals and triggers for monitoring changing risk, embed the strategy in statutory plans and practices, and socialise the strategy with the wider public in the context of competing priorities.
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	<span id="enabling-conditions-and-lessons-learned-from-practice"></span>		<span id="enabling-conditions-and-lessons-learned-from-practice"></span>
	=== 4.4.5 Enabling Conditions and Lessons Learned From ‘Practice’ ===		=== 4.4.5 Enabling Conditions and Lessons Learned From ‘Practice’ ===
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	<span id="c-citation"></span>		<span id="c-citation"></span>

	== Supplementary Material ==		== Supplementary Material ==

Laura: /* 4.4.4.3.5 Research needs */

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4.4.4.3.5 Research needs

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	<span id="box-4.4-community-based-experiences-canadian-arctic-and-hawkes-bay-new-zealand"></span>		<span id="box-4.4-community-based-experiences-canadian-arctic-and-hawkes-bay-new-zealand"></span>
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	== Box 4.4 Community Based Experiences: Canadian Arctic and Hawkes Bay, New Zealand ==		== Box 4.4 Community Based Experiences: Canadian Arctic and Hawkes Bay, New Zealand ==

Laura: /* Box 4.3 Responses to Sea Level Rise */

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Box 4.3 Responses to Sea Level Rise

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	<span id="observed-and-projected-responses-their-costs-benefits-co-benefits-drawbacks-efficiency-and-governance"></span>		<span id="observed-and-projected-responses-their-costs-benefits-co-benefits-drawbacks-efficiency-and-governance"></span>
	=== 4.4.2 Observed and Projected Responses, their Costs, Benefits, Co-benefits, Drawbacks, Efficiency and Governance ===		=== 4.4.2 Observed and Projected Responses, their Costs, Benefits, Co-benefits, Drawbacks, Efficiency and Governance ===
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	<span id="box-4.4-community-based-experiences-canadian-arctic-and-hawkes-bay-new-zealand"></span>		<span id="box-4.4-community-based-experiences-canadian-arctic-and-hawkes-bay-new-zealand"></span>

	== Box 4.4 Community Based Experiences: Canadian Arctic and Hawkes Bay, New Zealand ==		== Box 4.4 Community Based Experiences: Canadian Arctic and Hawkes Bay, New Zealand ==

Laura: /* 4.4.1 Introduction */

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4.4.1 Introduction

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	<span id="box-4.3-responses-to-sea-level-rise"></span>		<span id="box-4.3-responses-to-sea-level-rise"></span>
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	== Box 4.3 Responses to Sea Level Rise ==		== Box 4.3 Responses to Sea Level Rise ==

Laura: /* Box 4.2 Methodological Advances in Exposure and Vulnerability Assessments */

2026-06-01T08:38:13Z

Box 4.2 Methodological Advances in Exposure and Vulnerability Assessments

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	The use of vulnerability functions has been shown to be helpful in assessing the damage response of buildings to tsunamis (Tarbotton et al., 2015<sup>[[#fn:r925\|925]]</sup>), to coastal surge and wave hazards (Hatzikyriakou and Lin, 2017<sup>[[#fn:r926\|926]]</sup>) and accounting for non-linear relationships between mortality and temperature above a ‘comfort temperature’ (El-Zein and Tonmoy, 2017<sup>[[#fn:r927\|927]]</sup>). Acknowledging the non-compensatory nature of different vulnerability indicators (e.g., proximity to the sea cannot always be fully compensated by being wealthy), the concepts of preference, indifference and dominance thresholds have been applied as a form of data aggregation (Tonmoy and El-Zein, 2018<sup>[[#fn:r928\|928]]</sup>). Similar to advances in exposure assessments, freely available data and mobile technologies hold promise for enabling better input data for vulnerability assessments. Examples include using a combination of mobile phone and satellite data to determine and monitor vulnerability indicators such as poverty (Steele et al., 2017), and using data on subnational dependency ratios and high resolution gridded age/sex group datasets (Pezzulo et al., 2017<sup>[[#fn:r930\|930]]</sup>).		The use of vulnerability functions has been shown to be helpful in assessing the damage response of buildings to tsunamis (Tarbotton et al., 2015<sup>[[#fn:r925\|925]]</sup>), to coastal surge and wave hazards (Hatzikyriakou and Lin, 2017<sup>[[#fn:r926\|926]]</sup>) and accounting for non-linear relationships between mortality and temperature above a ‘comfort temperature’ (El-Zein and Tonmoy, 2017<sup>[[#fn:r927\|927]]</sup>). Acknowledging the non-compensatory nature of different vulnerability indicators (e.g., proximity to the sea cannot always be fully compensated by being wealthy), the concepts of preference, indifference and dominance thresholds have been applied as a form of data aggregation (Tonmoy and El-Zein, 2018<sup>[[#fn:r928\|928]]</sup>). Similar to advances in exposure assessments, freely available data and mobile technologies hold promise for enabling better input data for vulnerability assessments. Examples include using a combination of mobile phone and satellite data to determine and monitor vulnerability indicators such as poverty (Steele et al., 2017), and using data on subnational dependency ratios and high resolution gridded age/sex group datasets (Pezzulo et al., 2017<sup>[[#fn:r930\|930]]</sup>).
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	<span id="dimensions-of-exposure-and-vulnerability-to-sea-level-rise"></span>		<span id="dimensions-of-exposure-and-vulnerability-to-sea-level-rise"></span>
	=== 4.3.2 Dimensions of Exposure and Vulnerability to Sea Level Rise ===		=== 4.3.2 Dimensions of Exposure and Vulnerability to Sea Level Rise ===
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	<span id="responding-to-sea-level-rise"></span>		<span id="responding-to-sea-level-rise"></span>

	== 4.4. Responding to Sea Level Rise ==		== 4.4. Responding to Sea Level Rise ==

Laura: /* 4.3.1 Introduction */

2026-06-01T08:37:34Z

4.3.1 Introduction

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	<span id="box-4.2-methodological-advances-in-exposure-and-vulnerability-assessments"></span>		<span id="box-4.2-methodological-advances-in-exposure-and-vulnerability-assessments"></span>
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	== Box 4.2 Methodological Advances in Exposure and Vulnerability Assessments ==		== Box 4.2 Methodological Advances in Exposure and Vulnerability Assessments ==

Laura: /* Box 4.1 Case Studies of Coastal Hazard and Response */

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Box 4.1 Case Studies of Coastal Hazard and Response

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	Coastal hazard for the Nile delta arises because large portions lie only ±1.5 m above sea level (Shaltout et al., 2015<sup>[[#fn:r848\|848]]</sup>) and while the Delta includes only 2% of Egypt’s total area, it held 41% of its population as of 2006 (Hereher, 2010<sup>[[#fn:r849\|849]]</sup>; World Bank, 2017<sup>[[#fn:r850\|850]]</sup>) and is key to Egypt’s economy (Bucx et al., 2010<sup>[[#fn:r851\|851]]</sup>). The delta is an important resource for Egypt’s ﬁsh farms (Hereher, 2009<sup>[[#fn:r852\|852]]</sup>; El-Sayed, 2016<sup>[[#fn:r853\|853]]</sup>) and contains more than 63% of Egypt’s cultivated lands (Hereher, 2010<sup>[[#fn:r854\|854]]</sup>). The Nile Delta’s coastal lagoons are internationally renowned for abundant bird life, account for one fourth of Mediterranean wetlands and 60% of Egypt’s fish catch (Government of Egypt, 2016<sup>[[#fn:r855\|855]]</sup>). Coastal flooding and salinisation of freshwater lagoons would negatively affect fisheries and biodiversity (UNDP, 2017<sup>[[#fn:r856\|856]]</sup>).		Coastal hazard for the Nile delta arises because large portions lie only ±1.5 m above sea level (Shaltout et al., 2015<sup>[[#fn:r848\|848]]</sup>) and while the Delta includes only 2% of Egypt’s total area, it held 41% of its population as of 2006 (Hereher, 2010<sup>[[#fn:r849\|849]]</sup>; World Bank, 2017<sup>[[#fn:r850\|850]]</sup>) and is key to Egypt’s economy (Bucx et al., 2010<sup>[[#fn:r851\|851]]</sup>). The delta is an important resource for Egypt’s ﬁsh farms (Hereher, 2009<sup>[[#fn:r852\|852]]</sup>; El-Sayed, 2016<sup>[[#fn:r853\|853]]</sup>) and contains more than 63% of Egypt’s cultivated lands (Hereher, 2010<sup>[[#fn:r854\|854]]</sup>). The Nile Delta’s coastal lagoons are internationally renowned for abundant bird life, account for one fourth of Mediterranean wetlands and 60% of Egypt’s fish catch (Government of Egypt, 2016<sup>[[#fn:r855\|855]]</sup>). Coastal flooding and salinisation of freshwater lagoons would negatively affect fisheries and biodiversity (UNDP, 2017<sup>[[#fn:r856\|856]]</sup>).

	The Nile Delta’s low elevation translates into high exposure to SLR (Shaltout et al., 2015<sup>[[#fn:r857\|857]]</sup>), and the level of protection varies greatly from place to place (Frihy et al., 2010<sup>[[#fn:r858\|858]]</sup>). Box 4.1, Figure 1 indicates that episodic flooding will increase substantially without effective adaptation measures. An estimated 2660 km 2 in the northern delta will be inundated by 2100 for GMSL of 0.44 m (Gebremichael et al., 2018<sup>[[#fn:r859\|859]]</sup>; ''low confidence''), which is comparable to the RCP2.6 emission scenario. In addition, subsidence due to sediment diversion by the Aswan High Dam, water and natural gas extraction (Gebremichael et al., 2018<sup>[[#fn:r860\|860]]</sup>) and some other critical natural aspects (Frihy et al., 2010<sup>[[#fn:r861\|861]]</sup>) heightens vulnerability to coastal flooding (Box 4.1, Table 3) and reduces fresh water supply to the delta. Subsidence rates range from 0.4 mm yr –1 in the west delta to 1.1 mm yr –1 in the mid-delta and 3.4 mm yr –1 in the east delta (Elshinnawy et al., 2010<sup>[[#fn:r862\|862]]</sup>), although rates as high as 10 mm yr –1 near natural gas extraction operations are also reported (Gebremichael et al., 2018<sup>[[#fn:r863\|863]]</sup>). While there is ''low confidence'' in reported values, these indicate that subsidence makes locally a substantial contribution to RSL. Future construction of Ethiopia’s Grand Renaissance Dam (Stanley and Clemente, 2017<sup>[[#fn:r864\|864]]</sup>) may heighten problems of fresh water availability and reduce hydropower production.		The Nile Delta’s low elevation translates into high exposure to SLR (Shaltout et al., 2015<sup>[[#fn:r857\|857]]</sup>), and the level of protection varies greatly from place to place (Frihy et al., 2010<sup>[[#fn:r858\|858]]</sup>). Box 4.1, Figure 1 indicates that episodic flooding will increase substantially without effective adaptation measures. An estimated 2660 km 2 in the northern delta will be inundated by 2100 for GMSL of 0.44 m (Gebremichael et al., 2018<sup>[[#fn:r859\|859]]</sup>; ''low confidence''), which is comparable to the RCP2.6 emission scenario. In addition, subsidence due to sediment diversion by the Aswan High Dam, water and natural gas extraction (Gebremichael et al., 2018<sup>[[#fn:r860\|860]]</sup>) and some other critical natural aspects (Frihy et al., 2010<sup>[[#fn:r861\|861]]</sup>) heightens vulnerability to coastal flooding (Box 4.1, Table 3) and reduces fresh water supply to the delta. Subsidence rates range from 0.4 mm yr –1 in the west delta to 1.1 mm yr –1 in the mid-delta and 3.4 mm yr –1 in the east delta (Elshinnawy et al., 2010<sup>[[#fn:r862\|862]]</sup>), although rates as high as 10 mm yr –1 near natural gas extraction operations are also reported (Gebremichael et al., 2018<sup>[[#fn:r863\|863]]</sup>). While there is ''low confidence'' in reported values, these indicate that subsidence makes locally a substantial contribution to RSL. Future construction of Ethiopia’s Grand Renaissance Dam (Stanley and Clemente, 2017<sup>[[#fn:r864\|864]]</sup>) may heighten problems of fresh water availability and reduce hydropower production.

	The low-lying northern coast and Nile Delta region are a high priority for adaptation to climate change (UNDP, 2017<sup>[[#fn:r865\|865]]</sup>). The Egyptian government has committed 200 million USD to hard coastal protection at Alexandria and adopted integrated coastal zone management for the northern coast. Recent activities include integrating SLR risks within adaptation planning for social-ecological systems, with special focus on coastal urban areas, agriculture, migration and other human security dimensions (Government of Egypt, 2016<sup>[[#fn:r866\|866]]</sup>; UNDP, 2017<sup>[[#fn:r867\|867]]</sup>).		The low-lying northern coast and Nile Delta region are a high priority for adaptation to climate change (UNDP, 2017<sup>[[#fn:r865\|865]]</sup>). The Egyptian government has committed 200 million USD to hard coastal protection at Alexandria and adopted integrated coastal zone management for the northern coast. Recent activities include integrating SLR risks within adaptation planning for social-ecological systems, with special focus on coastal urban areas, agriculture, migration and other human security dimensions (Government of Egypt, 2016<sup>[[#fn:r866\|866]]</sup>; UNDP, 2017<sup>[[#fn:r867\|867]]</sup>).
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	== 4.3 Exposure, Vulnerability, Impacts and Risk Related to Sea Level Rise ==		== 4.3 Exposure, Vulnerability, Impacts and Risk Related to Sea Level Rise ==

Laura: /* 4.2.3.5 Long-Term Scenarios, Beyond 2100 */

2026-06-01T08:36:17Z

4.2.3.5 Long-Term Scenarios, Beyond 2100

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	== Box 4.1 Case Studies of Coastal Hazard and Response ==		== Box 4.1 Case Studies of Coastal Hazard and Response ==

Laura: /* Executive Summary */

2026-06-01T08:33:42Z

Executive Summary

Show changes