Jump to content
Main menu
Main menu
move to sidebar
hide
Navigation
Main page
Recent changes
Random page
Help about MediaWiki
Special pages
ClimateKG
Search
Search
English
Appearance
Create account
Log in
Personal tools
Create account
Log in
Pages for logged out editors
learn more
Contributions
Talk
Editing
IPCC:AR6/WGII/Chapter-9
(section)
IPCC
Discussion
English
Read
Edit source
View history
Tools
Tools
move to sidebar
hide
Actions
Read
Edit source
View history
General
What links here
Related changes
Page information
In other projects
Appearance
move to sidebar
hide
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
===== 9.9.4.1.2 Sea level rise and coastal flooding ===== <div id="h4-26-siblings" class="h4-siblings"></div> Africa’s low-lying coastal zone population is expected to grow more than any other region from 2000 to 2060 (see Figure 9.28; [[#Neumann--2015|Neumann et al., 2015]] ). Future rapid coastal development is expected to increase existing high vulnerabilities to sea level rise (SLR) and coastal hazards, particularly in east Africa ( ''high confidence'' ) (Figure 9.29; [[#Hinkel--2012|Hinkel et al., 2012]] ; [[#Kulp--2019|Kulp and Strauss, 2019]] ). By 2100, sea levels are projected to rise at least 40 cm above those in 2000 in a below 2°C scenario, and possibly up to 1 m by the end of the century under a 4°C warming scenario ( [[#Serdeczny--2017|Serdeczny et al., 2017]] ; see also Cross-Chapter Box SLR in Chapter 3). <div id="_idContainer084" class="Figure"></div> [[File:112cbee81c32c023e3fdb2f8c1e6b9b0 IPCC_AR6_WGII_Figure_9_028.png]] '''Figure 9.28 |''' '''Tens to hundreds of millions of people in Africa are projected to be exposed to sea level rise, with a major risk driver being increased exposure due to population increase in low-lying areas.''' '''(a)''' Population in the low-elevation coastal zone (LECZ) projected to be exposed to mean sea level rise (SLR) for 2030 (+10 cm SLR) and 2060 (+21 cm SLR). Scenarios A, C have exclusive social, political and economic governance whereas scenarios B and D have inclusive social, political and economic governance. '''(b)''' African countries with the highest projected population numbers in the LECZ, and also the additional population projected to be exposed in these countries due to a 1-in-100 year storm surge event. For panel b projections of population exposure used the high population growth socio-economic scenario (scenario C). Data sourced from [[#Neumann--2015|Neumann et al. (2015)]] . <div id="_idContainer086" class="Figure"></div> [[File:5a391848b4f227f3ceb881fd706a9c8d IPCC_AR6_WGII_Figure_9_029.png]] '''Figure 9.29 |''' '''Multiple large African cities will be exposed to sea level rise (SLR), these include the selected examples:''' '''(a)''' Dar es Salaam, Bagamoyo, and Stone Town in Tanzania (east Africa), '''(b)''' Lagos in Nigeria, and Cotonou and Porto-Novo in Benin (west Africa) and '''(c)''' Cairo and Alexandria in Egypt (north Africa). Orange shows built-up area in 2014. Shades of blue show permanent flooding due to SLR by 2050 and 2100 under low (RCP2.6), intermediate (RCP4.5) and high (RCP8.5) greenhouse gas emissions scenarios. Darker colours for higher emissions scenarios show areas projected to be flooded in addition to those for lower emissions scenarios. The figure assumes failure of coastal defences in 2050 and 2100. Some areas are already below current SLR and coastal defences need to be upgraded as SLRs (e.g., in Egypt), others are just above mean sea levels and they do not necessarily have high protection levels, so these defences need to be built (e.g., Dar es Salaam and Lagos). Blue shading shows permanent inundation surfaces predicted by Coastal Digital Elevation Model (DEM) and Shuttle Radar Topography Mission (SRTM) given the 95th percentile K14/RCP2.6, RCP4.5 and RCP8.5, for present day, 2050, and 2100 sea level projection for permanent inundation (inundation without a storm surge event), and RL10 (10-year return level storm) ( [[#Kulp--2019|Kulp and Strauss, 2019]] ). Low-lying areas isolated from the ocean are removed from the inundation surface using connected components analysis. Current water bodies are derived from the SRTM Water Body Dataset. Orange areas represent the extent of coastal human settlements in 2014 ( [[#Corbane--2018|Corbane et al., 2018]] ). See Figure CCP4.7 for projections including subsidence and worst-case scenario projections for 2100. In the absence of any adaptation, Egypt, Mozambique, and Nigeria are projected to be worst affected by SLR in terms of the number of people at risk of flooding annually in a 4°C warming scenario ( [[#Hinkel--2012|Hinkel et al., 2012]] ). Recent estimates have explored the potential damages due to SLR and coastal extreme events in 12 major African cities using a stochastic approach to account for uncertainty ( [[#Abadie--2020|Abadie et al., 2020]] ). The aggreate of expected average damages to these cities in 2050 is USD 65 billion for RCP4.5 and USD 86.5 billion for RCP8.5, and USD 137.5 billion under a high-end scenario that incorporates expert opinion on additional ice sheet melting with damages up to (Table 9.8). When considering low-probability, high-damage events, aggregate damage risks can be more than twice as high, reaching USD 187 billion and USD 206 billion under RCP4.5 and RCP8.5 scenarios, respectively, and USD 397 billion under the high-end scenario. City characteristics and exposure play a larger role in expected damages and risk than changes in sea level. The city of Alexandria in north Africa leads the ranking, with aggregate expected damage of USD 36 billion and USD 50 billion under RCP4.5 and RCP8.5 scenarios, respectively, and USD 79.4 billion under a high-end scenario. Sea level rise and associated episodic flooding are identified as key drivers of projected net migration of 750,000 people out of the east African coastal zone between 2020 and 2050 ( [[#IPCC--2019a|IPCC, 2019a]] ). These trends, alongside the emergence of ‘hotspots’ of climate in- and out-migration (Box 9.8), will have major implications for climate-sensitive sectors and the adequacy of human settlements, including urban infrastructure and social support systems. Actions which could help reduce the number of people being forced to move in distress, include adoption of inclusive and CRD policies, together with targeted investments to manage the reality of climate migration; and mainstreaming climate migration in development planning (Box 9.8). '''Table 9.8 |''' Regional relative sea level rise (SLR) for 2050 and 2100, and associated aggregated expected damage risks over the period 2020 to 2050 in 12 major African coastal cities under four SLR scenarios. '''(a)''' Regional relative SLR by 2050 and 2100. For SLR, median and 95th percentiles are presented, in centimetres. '''(b)''' Probabilistic damage estimations by 2050 include expected average damages (EAD), damages at the 95th percentile (value at risk; VaR) and the expected shortfall (ES), which represents the average damages of the 5% worst cases. Four relative sea level projections were considered under no adaptation: the RCP2.6, 4.5 and 8.5 scenarios from the ( [[#IPCC--2014a|IPCC, 2014a]] ), and a high-end RCP8.5 scenario that incorporates expert opinion on additional ice sheet melting. Note that figures are provided in undiscounted millions of US dollars (2005) and have been rounded off to avoid a false sense of precision ( [[#Abadie--2020|Abadie et al., 2020]] ; [[#Abadie--2021|Abadie et al., 2021]] ). {| class="wikitable" |- ! colspan="13"| (a) Regional relative sea level rise (cm) |- ! rowspan="2"| City ! rowspan="2"| Year ! colspan="3"| RCP2.6 ! colspan="3"| RCP4.5 ! colspan="3"| RCP8.5 ! colspan="2"| High-end |- ! colspan="2"| Median ! P95 ! colspan="2"| Median ! P95 ! colspan="2"| Median ! P95 ! Median ! P95 |- | rowspan="2"| '''Abidjan''' | '''2050''' | colspan="2"| '''21''' | '''30''' | colspan="2"| '''22''' | '''32''' | colspan="2"| '''24''' | '''34''' | '''28''' | '''48''' |- | '''2100''' | colspan="2"| '''44''' | '''69''' | colspan="2"| '''53''' | '''86''' | colspan="2"| '''75''' | '''114''' | '''86''' | '''206''' |- | rowspan="2"| '''Alexandria''' | '''2050''' | colspan="2"| '''18''' | '''26''' | colspan="2"| '''18''' | '''28''' | colspan="2"| '''21''' | '''30''' | '''25''' | '''43''' |- | '''2100''' | colspan="2"| '''36''' | '''58''' | colspan="2"| '''46''' | '''73''' | colspan="2"| '''67''' | '''102''' | '''78''' | '''186''' |- | rowspan="2"| '''Algiers''' | '''2050''' | colspan="2"| '''19''' | '''27''' | colspan="2"| '''19''' | '''29''' | colspan="2"| '''22''' | '''31''' | '''25''' | '''45''' |- | '''2100''' | colspan="2"| '''39''' | '''62''' | colspan="2"| '''47''' | '''76''' | colspan="2"| '''66''' | '''98''' | '''78''' | '''192''' |- | rowspan="2"| '''Cape Town''' | '''2050''' | colspan="2"| '''20''' | '''30''' | colspan="2"| '''21''' | '''31''' | colspan="2"| '''23''' | '''33''' | '''27''' | '''48''' |- | '''2100''' | colspan="2"| '''44''' | '''69''' | colspan="2"| '''53''' | '''87''' | colspan="2"| '''75''' | '''117''' | '''86''' | '''199''' |- | rowspan="2"| '''Casablanca''' | '''2050''' | colspan="2"| '''19''' | '''27''' | colspan="2"| '''20''' | '''29''' | colspan="2"| '''22''' | '''31''' | '''26''' | '''46''' |- | '''2100''' | colspan="2"| '''39''' | '''63''' | colspan="2"| '''47''' | '''78''' | colspan="2"| '''65''' | '''99''' | '''77''' | '''198''' |- | rowspan="2"| '''Dakar''' | '''2050''' | colspan="2"| '''21''' | '''31''' | colspan="2"| '''21''' | '''31''' | colspan="2"| '''23''' | '''33''' | '''27''' | '''48''' |- | '''2100''' | colspan="2"| '''43''' | '''69''' | colspan="2"| '''53''' | '''86''' | colspan="2"| '''73''' | '''111''' | '''85''' | '''209''' |- | rowspan="2"| '''Dar es Salaam''' | '''2050''' | colspan="2"| '''20''' | '''29''' | colspan="2"| '''21''' | '''31''' | colspan="2"| '''24''' | '''33''' | '''27''' | '''47''' |- | '''2100''' | colspan="2"| '''45''' | '''70''' | colspan="2"| '''54''' | '''86''' | colspan="2"| '''76''' | '''117''' | '''87''' | '''206''' |- | rowspan="2"| '''Durban''' | '''2050''' | colspan="2"| '''20''' | '''30''' | colspan="2"| '''22''' | '''32''' | colspan="2"| '''25''' | '''34''' | '''28''' | '''49''' |- | '''2100''' | colspan="2"| '''46''' | '''72''' | colspan="2"| '''55''' | '''90''' | colspan="2"| '''78''' | '''119''' | '''89''' | '''207''' |- | rowspan="2"| '''Lagos''' | '''2050''' | colspan="2"| '''21''' | '''30''' | colspan="2"| '''22''' | '''32''' | colspan="2"| '''24''' | '''34''' | '''28''' | '''48''' |- | '''2100''' | colspan="2"| '''44''' | '''69''' | colspan="2"| '''54''' | '''86''' | colspan="2"| '''75''' | '''113''' | '''86''' | '''205''' |- | rowspan="2"| '''Lome''' | '''2050''' | colspan="2"| '''21''' | '''30''' | colspan="2"| '''22''' | '''32''' | colspan="2"| '''24''' | '''34''' | '''28''' | '''48''' |- | '''2100''' | colspan="2"| '''44''' | '''69''' | colspan="2"| '''53''' | '''86''' | colspan="2"| '''76''' | '''115''' | '''87''' | '''205''' |- | rowspan="2"| '''Luanda''' | '''2050''' | colspan="2"| '''21''' | '''30''' | colspan="2"| '''23''' | '''32''' | colspan="2"| '''25''' | '''35''' | '''29''' | '''49''' |- | '''2100''' | colspan="2"| '''45''' | '''70''' | colspan="2"| '''55''' | '''88''' | colspan="2"| '''78''' | '''119''' | '''90''' | '''205''' |- | rowspan="2"| '''Maputo''' | '''2050''' | colspan="2"| '''21''' | '''31''' | colspan="2"| '''22''' | '''32''' | colspan="2"| '''24''' | '''34''' | '''28''' | '''49''' |- | '''2100''' | colspan="2"| '''45''' | '''71''' | colspan="2"| '''55''' | '''89''' | colspan="2"| '''78''' | '''120''' | '''89''' | '''209''' |- | colspan="13"| '''(b) Expected average damages and risk measures (USD millions)''' |- | rowspan="2"| '''City''' | colspan="3"| '''RCP2.6''' | colspan="3"| '''RCP4.5''' | colspan="3"| '''RCP8.5''' | colspan="3"| '''High-end scenario''' |- | '''EAD''' | '''VaR(95%)''' | '''ES(95%)''' | '''EAD''' | '''VaR(95%)''' | '''ES(95%)''' | '''EAD''' | '''VaR(95%)''' | '''ES(95%)''' | '''EAD''' | '''VaR(95%)''' | '''ES(95%)''' |- | '''Abidjan''' | '''14,290''' | '''33,910''' | '''41,690''' | '''16,730''' | '''38,230''' | '''46,390''' | '''20,910''' | '''42,140''' | '''49,550''' | '''32,670''' | '''77,750''' | '''96,570''' |- | '''Alexandria''' | '''32,840''' | '''74,100''' | '''92,470''' | '''36,220''' | '''83,700''' | '''104,270''' | '''49,990''' | '''99,500''' | '''117,580''' | '''79,360''' | '''180,090''' | '''221,390''' |- | '''Algiers''' | '''270''' | '''620''' | '''760''' | '''300''' | '''700''' | '''870''' | '''390''' | '''810''' | '''960''' | '''640''' | '''1,540''' | '''1,920''' |- | '''Cape Town''' | '''110''' | '''310''' | '''400''' | '''130''' | '''360''' | '''450''' | '''170''' | '''410''' | '''490''' | '''300''' | '''800''' | '''1,010''' |- | '''Casablanca''' | '''350''' | '''1,150''' | '''1,520''' | '''420''' | '''1,340''' | '''1,740''' | '''610''' | '''1,570''' | '''1,930''' | '''1,230''' | '''3,590''' | '''4,630''' |- | '''Dakar''' | '''590''' | '''1,310''' | '''1,590''' | '''620''' | '''1,390''' | '''1,690''' | '''760''' | '''1,530''' | '''1,800''' | '''1,180''' | '''2,880''' | '''3,610''' |- | '''Dar es Salaam''' | '''880''' | '''2,100''' | '''2,600''' | '''1,050''' | '''2,440''' | '''2,970''' | '''1,360''' | '''2,760''' | '''3,250''' | '''2,140''' | '''5,120''' | '''6,360''' |- | '''Durban''' | '''110''' | '''370''' | '''470''' | '''150''' | '''420''' | '''530''' | '''210''' | '''490''' | '''590''' | '''370''' | '''970''' | '''1,230''' |- | '''Lagos''' | '''3,680''' | '''6,790''' | '''7,950''' | '''4,200''' | '''7,660''' | '''8,930''' | '''4,920''' | '''8,270''' | '''9,420''' | '''6,750''' | '''13,820''' | '''16,730''' |- | '''Lome''' | '''3,230''' | '''10,480''' | '''13,460''' | '''4,280''' | '''12,580''' | '''15,780''' | '''5,980''' | '''14,430''' | '''17,380''' | '''10,720''' | '''28,580''' | '''36,010''' |- | '''Luanda''' | '''160''' | '''380''' | '''470''' | '''200''' | '''440''' | '''530''' | '''260''' | '''510''' | '''600''' | '''400''' | '''910''' | '''1,130''' |- | '''Maputo''' | '''650''' | '''1,990''' | '''2,530''' | '''700''' | '''2,080''' | '''2,620''' | '''980''' | '''2,410''' | '''2,910''' | '''1,790''' | '''4,830''' | '''6,110''' |- | '''Aggregate damage''' '''and risk''' | '''57,160''' | '''133,510''' | '''165,910''' | '''65,000''' | '''151,340''' | '''186,770''' | '''86,540''' | '''174,830''' | '''206,460''' | '''137,550''' | '''320,880''' | '''396,700''' |} <div id="9.9.4.1.3" class="h4-container"></div> <span id="drought"></span>
Summary:
Please note that all contributions to ClimateKG may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here.
You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see
ClimateKG:Copyrights
for details).
Do not submit copyrighted work without permission!
Cancel
Editing help
(opens in new window)
Search
Search
Editing
IPCC:AR6/WGII/Chapter-9
(section)
Add languages
Add topic
