Editing Cape Town (section)

== Geography and the natural environment ==
[[File:The Mother City - South Africa (2417714757).jpg|thumb|[[Devil's Peak (Cape Town)|Devil's Peak]], [[Table Mountain]] and [[Lion's Head (Cape Town)|Lion's Head]]]]
[[File:Cape fires (32827624088).jpg|thumb|Satellite image of Cape Town showing the [[Cape Peninsula]] (left), [[Cape Flats]] and [[False Bay]]]]
[[File:Table Mountain Cape Town South Africa 19Mar2018 SkySat.jpg|thumb|Satellite image 3D of the [[City Bowl]] and Table Mountain]]
Cape Town is located at latitude 33.55° S (approximately the same as [[Sydney]] and [[Buenos Aires]] and equivalent to [[Casablanca]] and [[Los Angeles]] in the northern hemisphere) and longitude 18.25° E.

[[Table Mountain]], with its near vertical cliffs and flat-topped summit over {{cvt|1000|m|ft}} high, and with [[Devil's Peak (Cape Town)|Devil's Peak]] and [[Lion's Head (Cape Town)|Lion's Head]] on either side, together form a dramatic mountainous backdrop enclosing the central area of Cape Town, the so-called [[City Bowl]].

A thin strip of cloud, known colloquially as the "tablecloth" ("Karos" in [[Afrikaans]]), sometimes forms on top of the mountain. To the immediate south of the city, the [[Cape Peninsula]] is a scenic mountainous spine jutting {{cvt|40|km}} southward into the [[Atlantic Ocean]] and terminating at [[Cape Point]].

There are over 70 peaks above {{cvt|300|m}} within [[City of Cape Town|Cape Town's official metropolitan limits]]. Many of the city's suburbs lie on the large plain called the [[Cape Flats]], which extends over {{cvt|50|km|-1}} to the east and joins the peninsula to the mainland. The Cape Town region is characterised by an extensive coastline, rugged mountain ranges, coastal plains and inland valleys.

=== Extent ===
The extent of Cape Town has varied considerably over time. It originated as a small settlement at the foot of Table Mountain and has grown beyond its city limits as a [[metropolitan area]] to encompass the entire [[Cape Peninsula]] to the south, the [[Cape Flats]], the [[Helderberg]] basin and part of the Steenbras catchment area to the east, and the Tygerberg hills, Blouberg and other areas to the north. [[Robben Island]] in Table Bay is also part of Cape Town. It is bounded by the Atlantic Ocean to the west, and False Bay to the south. To the north and east, the extent is demarcated by boundaries of neighbouring municipalities within the Western Cape province.

The official boundaries of the city proper extend between the [[City Bowl]] and the Atlantic Seaboard to the east and the [[Southern Suburbs, Cape Town|Southern Suburbs]] to the south. The [[City of Cape Town]], the [[metropolitan municipality]] that takes its name from the city covers the Greater Cape Town [[metropolitan area]], known as the Cape Metropole, extending beyond the city proper itself to include a number of satellite towns, suburbs and rural areas such as [[Atlantis, South Africa|Atlantis]], [[Bellville, South Africa|Bellville]], [[Blouberg, Western Cape|Blouberg]], [[Brackenfell]], [[Durbanville]], [[Goodwood, Western Cape|Goodwood]], [[Gordon's Bay]], [[Hout Bay]], [[Khayelitsha]], [[Kraaifontein]], [[Kuils River|Kuilsrivier]], [[Macassar, Western Cape|Macassar]], [[Melkbosstrand]], [[Milnerton]], [[Muizenberg]], [[Noordhoek, Cape Town|Noordhoek]], [[Parow, South Africa|Parow]], [[Philadelphia, South Africa|Philadelphia]], [[Simon's Town]], [[Somerset West]], and [[Strand, Western Cape|Strand]] among others.<ref>{{Cite web |title=Census 2011: Metropolitan Municipality: City of Cape Town |url=https://census2011.adrianfrith.com/place/199 |access-date=7 June 2023 |website=census2011.adrianfrith.com}}</ref><ref>{{Cite web |title=Census 2011: Main Place: Cape Town |url=https://census2011.adrianfrith.com/place/199041 |access-date=7 June 2023 |website=census2011.adrianfrith.com}}</ref>

The [[Cape Peninsula]] is {{cvt|52|km|-1}} long from [[Mouille Point]] in the north to Cape Point in the south,<ref name="Map 3318" /> with an area of about {{cvt|470|km2|sqmi}}, and it displays more topographical variety than other similar sized areas in southern Africa, and consequently spectacular scenery. There are diverse low-nutrient soils, large rocky outcrops, scree slopes, a mainly rocky coastline with embayed beaches, and considerable local variation in climatic conditions.<ref name="Cowling et al 1996" />

The sedimentary rocks of the [[Cape Supergroup]], of which parts of the Graafwater and Peninsula Formations remain, were uplifted between 280 and 21S million years ago, and were largely eroded away during the Mesozoic. The region was geologically stable during the Tertiary, which has led to slow denudation of the durable sandstones. Erosion rate and drainage has been influenced by fault lines and fractures, leaving remnant steep-sided massifs like Table Mountain surrounded by flatter slopes of deposits of the eroded material overlaying the older rocks,<ref name="Cowling et al 1996" />

There are two internationally notable landmarks, [[Table Mountain]] and [[Cape Point]], at opposite ends of the Peninsula Mountain Chain, with the [[Cape Flats]] and [[False Bay]] to the east and the [[Atlantic Ocean]] to the west. The landscape is dominated by sandstone plateaux and ridges, which generally drop steeply at their margins to the surrounding debris slopes, interrupted by a major gap at the Fish Hoek–Noordhoek valley.

In the south much of the area is a low sandstone plateau with sand dunes. Maximum altitude is 1113{{spaces}}m on Table Mountain.<ref name="Cowling et al 1996" /> The Cape Flats (Afrikaans: Kaapse Vlakte) is a flat, low-lying, sandy area, area to the east the Cape Peninsula, and west of the Helderberg much of which was wetland and dunes within recent history. To the north are the Tygerberg Hills and the Stellenbosch district.

The [[Helderberg]] area of Greater Cape Town, previously known as the "Hottentots-Holland" area, is mostly residential, but also a wine-producing area east of the Cape Flats, west of the Hottentots Holland mountain range and south of the Helderberg mountain, from which it gets its current name. The Helderberg consists of the previous municipalities of Somerset West, Strand, Gordons Bay and a few other towns. Industry and commerce is largely in service of the area.

After the Cape Peninsula, Helderberg is the next most mountainous part of Greater Cape Town, bordered to the north and east by the highest peaks in the region along the watershed of the Helderberg and Hottentots Holland Mountains, which are part of the Cape Fold Belt with [[Cape Supergroup]] strata on a basement of Tygerberg Formation rocks intruded by part of the Stellenbosch granite pluton. The region includes the entire catchment of the Lourens and Sir Lowry's rivers, separated by the Schapenberg hill, and a small part of the catchment of the Eerste River to the west. The Helderberg is ecologically highly diverse, rivaling the Cape Peninsula, and has its own endemic ecoregions and several conservation areas.

To the east of the Hottentots Holland mountains is the valley of the Steenbras River, in which the [[Steenbras Dam]] was built as a water supply for Cape Town. The dam has been supplemented by several other dams around the western Cape, some of them considerably larger. This is almost entirely a conservation area, of high biodiversity. [[Bellville, South Africa|Bellville]], [[Brackenfell]], [[Durbanville]], [[Kraaifontein]], [[Goodwood, Western Cape|Goodwood]] and [[Parow, South Africa|Parow]] are a few of the towns that make up the [[Northern Suburbs, Cape Town|Northern Suburbs]] of Cape Town. In current popular culture these areas are often referred to as being beyond the "[[boerewors]] curtain," a play on the term "[[iron curtain]]."

[[UNESCO]] declared [[Robben Island]] in the Western Cape a [[List of World Heritage Sites in Africa|World Heritage Site]] in 1999. Robben Island is located in Table Bay, some {{cvt|6|km}} west of Bloubergstrand, a coastal suburb north of Cape Town, and stands some 30m above sea level. Robben Island has been used as a [[Maximum Security Prison, Robben Island|prison]] where people were isolated, banished, and exiled for nearly 400 years. It was also used as a [[Leprosy|leper]] colony, a post office, a grazing ground, a mental hospital, and an outpost.<ref>{{Cite web |date=14 July 2011 |title=Robben Island |url=https://www.sahistory.org.za/article/robben-island |url-status=live |archive-url=https://web.archive.org/web/20190401181709/https://www.sahistory.org.za/article/robben-island |archive-date=1 April 2019 |access-date=24 July 2019 |website=South African History Online}}</ref>

{{wide image|Ciudad del Cabo desde Cabeza de León, Sudáfrica, 2018-07-22, DD 20-23 PAN.jpg|850px|Cape Town's "[[City Bowl]]" viewed from [[Lion's Head (Cape Town)|Lion's Head]] in May (late autumn)}}

=== Geology ===
{{Main|Geology of Cape Town}}
[[File:Geological map of the Cape Peninsula and False Bay.png|thumb|upright|left|Geological map of the Cape Peninsula and False Bay]]

The [[Cape Peninsula]] is a rocky and mountainous [[peninsula]] that juts out into the [[Atlantic Ocean]] at the south-western extremity of the continent. At its tip is Cape Point and the [[Cape of Good Hope]]. The peninsula forms the west side of False Bay and the Cape Flats. On the east side are the Helderberg and Hottentots Holland mountains.

The three main rock formations are the late-[[Precambrian]] Malmesbury group (sedimentary and metamorphic rock), the Cape Granite suit, comprising the huge Peninsula, Kuilsrivier-Helderberg, and Stellenbosch batholiths, that were intruded into the Malmesbury Group about 630 million years ago, and the [[Cape Fold Belt#Table Mountain group|Table Mountain group]] sandstones that were deposited on the eroded surface of the granite and Malmesbury series basement about 450 million years ago.

The sand, silt and mud deposits were lithified by pressure and then folded during the Cape Orogeny to form the [[Cape Fold Belt]], which extends in an arc along the western and southern coasts. The present landscape is due to prolonged erosion having carved out deep valleys, removing parts of the once continuous Table Mountain Group sandstone cover from over the Cape Flats and False Bay, and leaving high residual mountain ridges.<ref name="Compton 2004" />

At times the sea covered the Cape Flats and [[Noordhoek, Cape Town|Noordhoek]] valley and the Cape Peninsula was then a group of islands. During glacial periods the sea level dropped to expose the bottom of False Bay to weathering and erosion, with the last major regression leaving the entire bottom of False Bay exposed.

During this period an extensive system of dunes was formed on the sandy floor of False Bay. At this time the drainage outlets lay between Rocky Bank Cape Point to the west, and between Rocky Bank and Hangklip Ridge to the east, with the watershed roughly along the line of the contact zone east of Seal Island and Whittle Rock.<ref name="Compton 2004" /><ref name="Brown and Magoba 2009 part 1" />{{rp|Ch2}}

=== Climate ===
[[File:Llandudno Beach, Cape Town, Western Cape Province (6252674535).jpg|thumb|[[Llandudno, Western Cape]] during a sunny day]]
Cape Town has a [[Mediterranean climate]] ([[Köppen climate classification|Köppen]]: ''Csb'', bordering ''Csa''),<ref>{{Cite book |last=Robinson |first=Peter J. |title=Contemporary Climatology |last2=Henderson-Sellers |first2=Ann |publisher=Pearson Education Limited |year=1999 |isbn=9780582276314 |location=Harlow |page=123}}</ref><ref>{{Cite book |last=Rohli |first=Robert V. |url=https://books.google.com/books?id=WhtZKBCv7NMC |title=Climatology |last2=Vega |first2=Anthony J. |publisher=Jones & Bartlett Learning |year=2011 |isbn=9781449649548 |location=Sudbury, MA |page=250 |access-date=27 January 2016 |archive-url=https://web.archive.org/web/20161121014626/https://books.google.com/books?id=WhtZKBCv7NMC |archive-date=21 November 2016 |url-status=live}}</ref><ref>{{Cite web |title=Cape Point (South Africa) |url=http://gaw.empa.ch/gawsis/reports.asp?StationID=35 |url-status=dead |archive-url=https://web.archive.org/web/20130827135620/http://gaw.empa.ch/gawsis/reports.asp?StationID=35 |archive-date=27 August 2013 |access-date=20 May 2014 |website=Global Atmosphere Watch Station Information System (GAWSIS) |publisher=Federal Office of Meteorology and Climatology MeteoSwiss |quote=climate zone – Csb (Warm temperate climate with dry and warm summer)}}</ref> with mild, moderately wet winters and dry, warm summers. Winter, which lasts from June to September, may see large cold fronts entering for limited periods from the Atlantic Ocean with significant [[precipitation (meteorology)|precipitation]] and strong north-westerly winds. Winter months in the city average a maximum of {{cvt|18|C|0}} and minimum of {{cvt|8.5|C|0}}.

Winters are [[snow]] and [[frost]] free, except on Table Mountain and on other mountain peaks, where light accumulation of snow and frost can sometimes occur.<ref name="WMO">{{Cite web |title=World Weather Information Service – Cape Town |url=http://www.worldweather.org/035/c00138.htm |url-status=live |archive-url=https://web.archive.org/web/20100426062632/http://www.worldweather.org/035/c00138.htm |archive-date=26 April 2010 |access-date=4 May 2010}}</ref>
Total annual rainfall in the city averages {{cvt|515|mm|in|1}} although in the [[Southern Suburbs, Cape Town|Southern Suburbs]], close to the mountains, rainfall is significantly higher and averages closer to {{cvt|1000|mm|in|1|abbr=}}.

Summer, which lasts from December to March, is warm and dry with an average maximum of {{cvt|26|°C|0}} and minimum of {{cvt|16|°C|0}}. The region can get uncomfortably hot when the [[Berg Wind]], meaning "mountain wind", blows from the [[Karoo]] interior.

Spring and summer generally feature a strong wind from the south-east, known locally as the south-{{not a typo|easter}} or the [[Cape Doctor]], so called because it blows air pollution away. This wind is caused by a persistent [[Pressure system#High-pressure system|high-pressure system]] over the [[South Atlantic Ocean|South Atlantic]] to the west of Cape Town, known as the [[South Atlantic High]], which shifts latitude seasonally, following the sun, and influencing the strength of the fronts and their northward reach. Cape Town receives about 3,100 hours of sunshine per year.<ref name=NOAA/>

Water temperatures range greatly, between {{cvt|10|°C|0}} on the Atlantic Seaboard, to over {{cvt|22|°C|0}} in [[False Bay]]. Average annual ocean surface temperatures are between {{cvt|13|°C|0}} on the Atlantic Seaboard (similar to Californian waters, such as [[San Francisco]] or [[Big Sur]]), and {{cvt|17|°C|0}} in False Bay (similar to Northern Mediterranean temperatures, such as [[Nice]] or [[Monte Carlo]]).

Unlike other parts of the country the city does not have many [[thunderstorm]]s, and most of those that do occur, happen around October to December and March to April.
{{Weather box
| location = Cape Town ([[Cape Town International Airport]]) (1991–2020 normals)
| metric first = Y
| single line = Y
| Jan record high C = 45.2
| Feb record high C = 38.3
| Mar record high C = 43.0
| Apr record high C = 38.6
| May record high C = 33.5
| Jun record high C = 29.8
| Jul record high C = 29.0
| Aug record high C = 32.0
| Sep record high C = 33.1
| Oct record high C = 37.2
| Nov record high C = 39.9
| Dec record high C = 41.4
| Jan high C = 27.0
| Feb high C = 27.3
| Mar high C = 26.0
| Apr high C = 23.6
| May high C = 20.6
| Jun high C = 18.2
| Jul high C = 17.9
| Aug high C = 18.0
| Sep high C = 19.6
| Oct high C = 22.2
| Nov high C = 23.7
| Dec high C = 25.8
| Jan mean C = 21.8
| Feb mean C = 21.9
| Mar mean C = 20.5
| Apr mean C = 17.9
| May mean C = 15.4
| Jun mean C = 13.2
| Jul mean C = 12.7
| Aug mean C = 13.0
| Sep mean C = 14.5
| Oct mean C = 16.9
| Nov mean C = 18.6
| Dec mean C = 20.7
| Jan low C = 16.6
| Feb low C = 16.5
| Mar low C = 15.0
| Apr low C = 12.2
| May low C = 10.2
| Jun low C = 8.1
| Jul low C = 7.4
| Aug low C = 7.9
| Sep low C = 9.4
| Oct low C = 11.5
| Nov low C = 13.4
| Dec low C = 15.6
| Jan record low C = 7.4
| Feb record low C = 6.4
| Mar record low C = 4.6
| Apr record low C = 2.4
| May record low C = 0.9
| Jun record low C = -1.2
| Jul record low C = -1.3
| Aug record low C = -0.4
| Sep record low C = 0.2
| Oct record low C = 1.0
| Nov record low C = 3.9
| Dec record low C = 6.2
| precipitation colour = green
| Jan precipitation mm = 9.4
| Feb precipitation mm = 9.6
| Mar precipitation mm = 12.5
| Apr precipitation mm = 40.1
| May precipitation mm = 61.1
| Jun precipitation mm = 92.3
| Jul precipitation mm = 84.8
| Aug precipitation mm = 72.4
| Sep precipitation mm = 44.3
| Oct precipitation mm = 28.4
| Nov precipitation mm = 25.3
| Dec precipitation mm = 12.8
| year precipitation mm = 492.8
| unit precipitation days = 0.1 mm
| Jan precipitation days = 1.8
| Feb precipitation days = 1.8
| Mar precipitation days = 2.5
| Apr precipitation days = 5.0
| May precipitation days = 7.4
| Jun precipitation days = 10.1
| Jul precipitation days = 9.1
| Aug precipitation days = 9.3
| Sep precipitation days = 6.8
| Oct precipitation days = 4.2
| Nov precipitation days = 4.0
| Dec precipitation days = 2.6
| Jan humidity = 71
| Feb humidity = 72
| Mar humidity = 74
| Apr humidity = 78
| May humidity = 81
| Jun humidity = 81
| Jul humidity = 81
| Aug humidity = 80
| Sep humidity = 77
| Oct humidity = 74
| Nov humidity = 71
| Dec humidity = 71
| Jan sun = 352.3
| Feb sun = 304.0
| Mar sun = 289.7
| Apr sun = 240.1
| May sun = 196.7
| Jun sun = 175.9
| Jul sun = 197.0
| Aug sun = 206.2
| Sep sun = 228.4
| Oct sun = 283.5
| Nov sun = 302.8
| Dec sun = 338.4
| Jan uv = 12
| Feb uv = 11
| Mar uv = 8
| Apr uv = 5
| May uv = 3
| Jun uv = 2
| Jul uv = 2
| Aug uv = 4
| Sep uv = 6
| Oct uv = 8
| Nov uv = 10
| Dec uv = 12
| source = [[NOAA]] (humidity 1961–1990),<ref name="NOAA">{{Cite web |title=Cape Town/DF Malan Climate Normals 1961–1990 |url=ftp://ftp.atdd.noaa.gov/pub/GCOS/WMO-Normals/RA-I/UA/68816.TXT |access-date=8 April 2013 |publisher=[[National Oceanic and Atmospheric Administration]]}}</ref><ref>{{Cite web |title=Climate Normals 1991–2020 |url=https://www.nodc.noaa.gov/archive/arc0216/0253808/2.2/data/0-data/Region-1-WMO-Normals-9120/SouthAfrica/CSV/CapeTown_68816.csv |access-date=18 September 2018 |website=[[NOAA]]}}</ref> South African Weather Service,<ref>{{Cite web |date=28 October 2003 |title=Climate data: Cape Town |url=http://old.weathersa.co.za/Climat/Climstats/CapeTownStats.jsp |url-status=dead |archive-url=https://web.archive.org/web/20110314111749/http://old.weathersa.co.za/Climat/Climstats/CapeTownStats.jsp |archive-date=14 March 2011 |access-date=17 March 2011 |publisher=Old.weathersa.co.za}}</ref> eNCA<ref name="enca">{{Cite web |title=Hottest temperature |url=http://www.enca.com/south-africa/its-hottest-day-cape-town-century |url-status=live |archive-url=https://web.archive.org/web/20150720034623/http://www.enca.com/south-africa/its-hottest-day-cape-town-century |archive-date=20 July 2015 |access-date=6 March 2015 |publisher=enca.com}}</ref> |date=March 2011 }}

==== Climate change ====
A 2019 paper published in [[PLOS One]] estimated that under [[Representative Concentration Pathway#4.5|Representative Concentration Pathway 4.5]], a "moderate" scenario of [[climate change]] where global warming reaches ~{{cvt|2.5-3|C-change|F-change}} by 2100, the climate of Cape Town in the year 2050 would most closely resemble the current climate of [[Perth]] in [[Australia]].

The annual temperature would increase by {{cvt|1.1|C-change|F-change}}, and the temperature of the coldest month by {{cvt|0.3|C-change|F-change}}, while the temperature of the warmest month would be {{cvt|2.3|C-change|F-change}} higher.<ref>{{Cite journal |last=Bastin |first=Jean-Francois |last2=Clark |first2=Emily |last3=Elliott |first3=Thomas |last4=Hart |first4=Simon |last5=van den Hoogen |first5=Johan |last6=Hordijk |first6=Iris |last7=Ma |first7=Haozhi |last8=Majumder |first8=Sabiha |last9=Manoli |first9=Gabriele |last10=Maschler |first10=Julia |last11=Mo |first11=Lidong |last12=Routh |first12=Devin |last13=Yu |first13=Kailiang |last14=Zohner |first14=Constantin M. |last15=Thomas W. |first15=Crowther |date=10 July 2019 |title=Understanding climate change from a global analysis of city analogues |journal=PLOS ONE |volume=14 |issue=7 |at=S2 Table. Summary statistics of the global analysis of city analogues. |bibcode=2019PLoSO..1417592B |doi=10.1371/journal.pone.0217592 |pmc=6619606 |pmid=31291249 |doi-access=free}}</ref><ref>{{Cite web |title=Cities of the future: visualizing climate change to inspire action |url=https://crowtherlab.pageflow.io/cities-of-the-future-visualizing-climate-change-to-inspire-action |url-status=live |archive-url=https://web.archive.org/web/20230108082440/https://crowtherlab.pageflow.io/cities-of-the-future-visualizing-climate-change-to-inspire-action |archive-date=8 January 2023 |access-date=8 January 2023 |at=Current vs. future cities}}</ref> According to [[Climate Action Tracker]], the current warming trajectory appears consistent with {{cvt|2.7|C-change|F-change}}, which closely matches RCP 4.5.<ref>{{Cite web |title=The CAT Thermometer |url=https://climateactiontracker.org/global/cat-thermometer/ |url-status=live |archive-url=https://web.archive.org/web/20190414131223/https://climateactiontracker.org/global/cat-thermometer/ |archive-date=14 April 2019 |access-date=8 January 2023}}</ref>

Moreover, according to the 2022 [[IPCC Sixth Assessment Report]], Cape Town is one of 12 major African cities ([[Abidjan]], [[Alexandria]], [[Algiers]], Cape Town, [[Casablanca]], [[Dakar]], [[Dar es Salaam]], [[Durban]], [[Lagos]], [[Lomé]], [[Luanda]] and [[Maputo]]) which would be the most severely affected by future [[sea level rise]]. It estimates that they would collectively sustain cumulative damages of US$65 billion under RCP 4.5 and US$86.5 billion for the high-emission scenario RCP 8.5 by the year 2050.

Additionally, RCP 8.5 combined with the hypothetical impact from [[marine ice sheet instability]] at high levels of warming would involve up to US$137.5 billion in damages,{{Clarify|how would the damages occur? By what mechanism? To which areas?|date=March 2024}} while the additional accounting for the "low-probability, high-damage events" may increase aggregate risks to US$187 billion for the "moderate" RCP4.5, US$206 billion for RCP8.5 and US$397 billion under the high-end ice sheet instability scenario.<ref>Trisos, C.H., I.O. Adelekan, E. Totin, A. Ayanlade, J. Efitre, A. Gemeda, K. Kalaba, C. Lennard, C. Masao, Y. Mgaya, G. Ngaruiya, D. Olago, N.P. Simpson, and S. Zakieldeen 2022: [https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_Chapter09.pdf Chapter 9: Africa] {{Webarchive|url=https://web.archive.org/web/20221206082533/https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_Chapter09.pdf |date=6 December 2022 }}. In [https://www.ipcc.ch/report/ar6/wg2/ Climate Change 2022: Impacts, Adaptation and Vulnerability] {{Webarchive|url=https://web.archive.org/web/20220228114918/https://www.ipcc.ch/report/ar6/wg2/ |date=28 February 2022 }} [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, US, pp. 2043–2121</ref>

Since sea level rise would continue for about 10,000 years under every scenario of climate change, future costs of sea level rise would only increase, especially without adaptation measures.{{clarify|What adaptation measures?|date=March 2024}}<ref>{{Cite book |url=https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Full_Report.pdf |title=Technical Summary. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change |date=August 2021 |publisher=IPCC |page=TS14 |access-date=12 November 2021 |archive-url=https://web.archive.org/web/20210813201719/https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Full_Report.pdf |archive-date=13 August 2021 |url-status=live}}</ref>

=== Hydrology ===
<!-- {{main|Rivers of Cape Town}} -->
{{See also|Cape Peninsula#Drainage|Helderberg#Drainage|Cape Flats#Drainage}}

==== Sea surface temperatures ====
{{see also|False Bay#Waves, tides, water circulation and temperature|Cape Peninsula#Oceanography}}
[[File:Sea surface temperatures False Bay.png|thumb|left|upright=2.2|Charts of sea surface temperature in and near False Bay in summer and winter<ref name="Pfaff et al 2019" />]]
Cape Town's coastal water ranges from cold to mild, and the difference between the two sides of the peninsula can be dramatic. While the Atlantic Seaboard averages annual sea surface temperatures around {{cvt|13|°C|°F}}, the [[False Bay]] coast is much warmer, averaging between {{cvt|16|and|17|C|F}} annually.{{citation needed|date=June 2022}}

In summer, [[False Bay]] water averages slightly over {{cvt|20|°C|°F}}, with {{cvt|22|°C|°F}} an occasional high. Beaches located on the Atlantic Coast tend to have colder water due to the wind driven upwellings which contribute to the [[Benguela Current]] which originates off the Cape Peninsula, while the water at False Bay beaches may occasionally be warmer by up to {{cvt|10|C-change|0}} at the same time in summer.

In summer False Bay is thermally stratified, with a vertical temperature variation of 5 to 9˚C between the warmer surface water and cooler depths below 50{{spaces}}m, while in winter the water column is at nearly constant temperature at all depths. The development of a [[thermocline]] is strongest around late December and peaks in late summer to early autumn.<ref name="Coleman 2019" />{{rp|8}} In summer the south easterly winds generate a zone of upwelling near [[Pringle Bay|Cape Hangklip]], where surface water temperatures can be 6 to 7&nbsp;°C colder than the surrounding areas, and bottom temperatures below 12&nbsp;°C.<ref name="Coleman 2019" />{{rp|10}}

In the summer to early autumn (January–March), cold water upwelling near Cape Hangklip causes a strong surface temperature gradient between the south-western and north-eastern corners of the bay. In winter the surface temperature tends to be much the same everywhere. In the northern sector surface temperature varies a bit more (13 to 22{{spaces}}°C) than in the south (14 to 20{{spaces}}°C) during the year.<ref name="Pfaff et al 2019" />

Surface temperature variation from year to year is linked to the [[El Niño–Southern Oscillation]]. During El Niño years the South Atlantic high is shifted, reducing the south-easterly winds, so upwelling and evaporative cooling are reduced and sea surface temperatures throughout the bay are warmer, while in La Niña years there is more wind and upwelling and consequently lower temperatures. Surface water heating during El Niño increases vertical stratification. The relationship is not linear.<ref name="Pfaff et al 2019" /> Occasionally eddies from the Agulhas current will bring warmer water and vagrant sea life carried from the south and east coasts into False Bay.

=== Flora and fauna ===
{{Main|Biodiversity of Cape Town}}
[[File:Peninsula Sandstone Fynbos - Cape Town 8.JPG|thumb|[[Peninsula Sandstone Fynbos]] growing in [[Table Mountain National Park]].]]

Located in a [[Conservation International]] [[biodiversity hotspot]] as well as the unique [[Cape Floristic Region]], the city of Cape Town has one of the highest levels of [[biodiversity]] of any equivalent area in the world.<ref>{{Cite web |title=Brochures, booklets and posters |url=http://www.capetown.gov.za/en/EnvironmentalResourceManagement/publications/Pages/BrochuresBooklets.aspx |url-status=dead |archive-url=https://web.archive.org/web/20121223125053/http://www.capetown.gov.za/en/EnvironmentalResourceManagement/publications/Pages/Brochuresbooklets.aspx |archive-date=23 December 2012 |access-date=1 October 2011 |publisher=Capetown.gov.za}}</ref><ref name="fri1">{{Cite news |last=Friedman |first=Barbara |date=14 May 2021 |title=Cape Town recorded most sightings and species in world 2021 #CityNatureChallenge |url=https://www.capetalk.co.za/articles/416381/cape-town-recorded-most-sightings-and-species-in-world-citynaturechallenge2021 |url-status=live |archive-url=https://web.archive.org/web/20210519021337/https://www.capetalk.co.za/articles/416381/cape-town-recorded-most-sightings-and-species-in-world-citynaturechallenge2021 |archive-date=19 May 2021 |access-date=19 May 2021 |work=Lifestyle |publisher=capetalk.co.za |agency=Cape Talk 567 AM}}</ref>

These protected areas are a [[World Heritage Site]], and an estimated 2,200 species of plants are confined to Table Mountain – more than exist in the whole of the [[United Kingdom]] which has 1200 plant species and 67 endemic plant species.<ref>{{Cite web |title=Unique Biodiversity Poster |url=http://www.capetown.gov.za/en/EnvironmentalResourceManagement/publications/Documents/Biodiversity_poster-CT_Unique_Biodiv_SPECIES_2011-02.pdf |url-status=dead |archive-url=https://web.archive.org/web/20120725080811/http://www.capetown.gov.za/en/EnvironmentalResourceManagement/publications/Documents/Biodiversity_poster-CT_Unique_Biodiv_SPECIES_2011-02.pdf |archive-date=25 July 2012 |access-date=6 February 2013}}</ref><ref>{{Cite web |last=Cape Town Tourism |title=Vote for Table Mountain – Cape Town Tourism |url=http://www.capetown.travel/votefortablemountain/ |url-status=dead |archive-url=https://web.archive.org/web/20120112172911/http://www.capetown.travel/votefortablemountain/ |archive-date=12 January 2012 |access-date=12 January 2013 |publisher=Capetown.travel}}</ref><ref>{{Cite web |title=Western Cape |url=http://www.southafricaholiday.org.uk/places/p_western_cape.htm |url-status=dead |archive-url=https://web.archive.org/web/20121210202319/http://www.southafricaholiday.org.uk/places/p_western_cape.htm |archive-date=10 December 2012 |access-date=12 January 2013 |publisher=Southafricaholiday.org.uk}}</ref> Many of these species, including a great many types of [[protea]]s, are endemic to the mountain and can be found nowhere else.<ref>A.G. Rebelo, C. Boucher, N. Helme, L. Mucina, M.C. Rutherford et al. 2006. Fynbos Biome, in: L. Mucina & M.C. Rutherford (eds). ''The Vegetation of South Africa, Lesotho and Swaziland.''</ref>

It is home to a total of 19 different [[phytochorion|vegetation types]], of which several are [[endemic]] to the city and occur nowhere else in the world.<ref>{{Cite web |title=National Spatial Biodiversity Assessment 2005 Targets |url=http://www.capetown.gov.za/en/stats/Documents/Vegetation%20Types.mht |url-status=dead |archive-url=https://web.archive.org/web/20130824223150/http://www.capetown.gov.za/en/stats/Documents/Vegetation%20Types.mht |archive-date=24 August 2013 |access-date=24 February 2014 |publisher=Capetown.gov.za}}</ref>
It is also the only habitat of hundreds of endemic species,<ref>{{Cite web |title=Endemic Species of the city of Cape Town |url=http://www.capetown.gov.za/en/EnvironmentalResourceManagement/publications/Documents/Biodiv_fact_sheet_suppl_Endemic_spp_list_2010-03.pdf |url-status=dead |archive-url=https://web.archive.org/web/20111101122444/http://www.capetown.gov.za/en/EnvironmentalResourceManagement/publications/Documents/Biodiv_fact_sheet_suppl_Endemic_spp_list_2010-03.pdf |archive-date=1 November 2011}}</ref> and hundreds of others which are severely restricted or threatened. This enormous species diversity is mainly because the city is uniquely located at the convergence point of several different soil types and micro-climates.<ref>{{Cite journal |last=Lemaire |first=Benny |last2=Dlodlo |first2=Oscar |last3=Chimphango |first3=Samson |last4=Stirton |first4=Charles |last5=Schrire |first5=Brian |last6=Boatwright |first6=James S. |last7=Honnay |first7=Olivier |last8=Smets |first8=Erik |last9=Sprent |first9=Janet |last10=James |first10=Euan K. |last11=Muasya |first11=Abraham M. |date=2015 |title=Symbiotic diversity, specificity and distribution of rhizobia in native legumes of the Core Cape Subregion (South Africa) |url=https://academic.oup.com/femsec/article/91/2/1/2467736 |url-status=live |journal=FEMS Microbiology Ecology |volume=91 |issue=2 |pages=1–17 |doi=10.1093/femsec/fiu024 |pmid=25764552 |archive-url=https://web.archive.org/web/20210427033901/https://academic.oup.com/femsec/article/91/2/1/2467736 |archive-date=27 April 2021 |access-date=19 January 2021 |via=Oxford Academic |doi-access=free}}</ref><ref>{{Cite journal |last=Linder |first=H. P. |date=2003 |title=The radiation of the Cape flora, southern Africa |url=http://doi.wiley.com/10.1017/S1464793103006171 |url-status=live |journal=Biological Reviews |volume=78 |issue=4 |pages=597–638 |doi=10.1017/S1464793103006171 |pmid=14700393 |s2cid=43101616 |archive-url=https://web.archive.org/web/20210529140752/https://onlinelibrary.wiley.com/doi/abs/10.1017/S1464793103006171 |archive-date=29 May 2021 |access-date=19 January 2021}}</ref>

Table Mountain has an unusually rich biodiversity. Its vegetation consists predominantly of several different types of the unique and rich Cape [[Fynbos]]. The main vegetation type is endangered [[Peninsula Sandstone Fynbos]], but [[critically endangered]] [[Peninsula Granite Fynbos]], [[Peninsula Shale Renosterveld]] and [[Afromontane|Afromontane forest]] occur in smaller portions on the mountain.

Rapid [[population growth]] and [[Urbanisation|urban sprawl]] has covered much of these ecosystems with development. Consequently, Cape Town now has over 300 [[threatened]] plant species and 13 which are now [[extinct]]. The [[Cape Peninsula]], which lies entirely within the city of Cape Town, has the highest concentration of [[threatened species]] of any continental area of equivalent size in the world.<ref>{{Cite web |title=The View from The Cape: Extinction Risk, Protected Areas, and Climate Change |url=http://perceval.bio.nau.edu/downloads/grail/climate_seminar/section2/Hannah_etal05.pdf |url-status=dead |archive-url=https://web.archive.org/web/20130825180525/http://perceval.bio.nau.edu/downloads/grail/climate_seminar/section2/Hannah_etal05.pdf |archive-date=25 August 2013 |access-date=24 February 2014 |publisher=Perceval.bio.nau.edu}}</ref>

Tiny remnant populations of [[critically endangered]] or [[Extinct|near extinct]] plants sometimes survive on road sides, pavements and sports fields.<ref>[http://www.capetown.gov.za/en/EnvironmentalResourceManagement/publications/Documents/Biodiv_fact_sheet_8_threatened_species_2010-03.pdf]{{dead link|date=May 2017|bot=medic}}{{cbignore|bot=medic}}</ref> The remaining ecosystems are partially protected through a system of over 30 [[List of nature reserves in Cape Town|nature reserves]] – including the massive [[Table Mountain National Park]].<ref>{{Cite web |title=Table Mountain National Park |url=http://www.nature-reserve.co.za/cape-peninsula-national-park.html |url-status=live |archive-url=https://web.archive.org/web/20120605084259/http://www.nature-reserve.co.za/cape-peninsula-national-park.html |archive-date=5 June 2012 |access-date=9 July 2020 |publisher=nature-reserve.co.za}}</ref>

Cape Town reached first place in the 2019 iNaturalist City Nature Challenge in two out of the three categories: Most Observations, and Most Species. This was the first entry by Capetonians in this annual competition to observe and record the local biodiversity over a four-day long weekend during what is considered the worst time of the year for local observations.<ref name="Two Oceans">{{Cite web |date=7 May 2019 |title=Congratulations! Cape Town claims the top spot in the international City Nature Challenge 2019 |url=https://www.aquarium.co.za/blog/entry/cape-town-claims-the-top-spot-in-city-nature-challenge-2019 |url-status=live |archive-url=https://web.archive.org/web/20190805185315/https://www.aquarium.co.za/blog/entry/cape-town-claims-the-top-spot-in-city-nature-challenge-2019 |archive-date=5 August 2019 |access-date=5 August 2019}}</ref>

A worldwide survey suggested that the extinction rate of endemic plants from the City of Cape Town is one of the highest in the world, at roughly three per year since 1900 – partly a consequence of the very small and localised habitats and high endemicity.<ref name="Rebelo 2019">{{Cite web |last=Rebelo |first=Tony |date=12 June 2019 |title=And we feature again !!! Cape Town in the forefront ... |url=https://www.inaturalist.org/projects/city-nature-challenge-2019-cape-town/journal/25459 |url-status=live |archive-url=https://web.archive.org/web/20190805162241/https://www.inaturalist.org/projects/city-nature-challenge-2019-cape-town/journal/25459 |archive-date=5 August 2019 |access-date=5 August 2019 |website=iNaturalist}}</ref>