Editing Mount Kilimanjaro (section)

== Geology and geography ==
{{multiple image
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Kilimanjaro is a large dormant [[stratovolcano]] composed of three distinct volcanic cones: Kibo, the highest; Mawenzi at {{convert|5149|m|ft|abbr=on}};<ref>{{cite web |last1=Sharaf |first1=Yasir |title=Mount Kilimanjaro Volcanic Cones: Shira, Kibo And Mawenzi Peaks |url=https://xpatsinternational.com/mount-kilimanjaro-volcanic-cones-shira-kibo-and-mawenzi-peaks/ |website=XPATS International |access-date=25 September 2021 |ref=None |language=en |date=24 March 2016 |archive-date=5 November 2021 |archive-url=https://web.archive.org/web/20211105075701/https://xpatsinternational.com/mount-kilimanjaro-volcanic-cones-shira-kibo-and-mawenzi-peaks/ |url-status=live }}</ref> and Shira, the lowest at {{convert|4005|m|ft|abbr=on}}.<ref name="Kaser">{{cite journal |doi=10.1029/2006GL027084 |bibcode=2006GeoRL..3316502C |title=Kilimanjaro Glaciers: Recent areal extent from satellite data and new interpretation of observed 20th-century retreat rates |journal=Geophysical Research Letters |volume=33 |issue=16 |pages=L16502 |last1=Cullen |first1=Nicolas J. |last2=Mölg |first2=Thomas |last3=Kaser |first3=Georg |last4=Hussein |first4=Khalid |last5=Steffen |first5=Konrad |last6=Hardy |first6=Douglas R. |year=2006 |s2cid=14421037 }}</ref> Mawenzi and Shira are [[Volcano#Extinct|extinct]], while Kibo is [[Volcano#Dormant|dormant]] and could erupt again.<ref name="NonnottePhilippe">{{cite journal |doi=10.1016/j.jvolgeores.2007.12.042 |bibcode=2008JVGR..173...99N |title=New K Ar age determinations of Kilimanjaro volcano in the North Tanzanian diverging rift, East Africa |journal=Journal of Volcanology and Geothermal Research |volume=173 |issue=1 |page=99 |last1=Nonnotte |first1=Philippe |last2=Guillou |first2=Hervé |last3=Le Gall |first3=Bernard |last4=Benoit |first4=Mathieu |last5=Cotten |first5=Joseph |last6=Scaillet |first6=Stéphane |year=2008 |s2cid=18476938 |url=https://hal-insu.archives-ouvertes.fr/insu-00304458/file/Nonnotte_et_al.J.Volc.Geoth.Res-08.pdf |access-date=2019-01-08 |archive-url=https://web.archive.org/web/20190115023222/https://hal-insu.archives-ouvertes.fr/insu-00304458/file/Nonnotte_et_al.J.Volc.Geoth.Res-08.pdf |archive-date=2019-01-15 |url-status=live }}</ref>

Uhuru Peak is the highest summit on Kibo's crater rim. The [[Tanzania National Parks Authority]], a Tanzanian government agency,<ref name="XPATS International">{{cite web |last1=Sharaf |first1=Yasir |title=8 Common Mistakes I Wish I Knew Before Climbing Mount Kilimanjaro As A Beginner {{!}} How To Climb Mount Kilimanjaro? |url=https://xpatsinternational.com/climbing-mount-kilimanjaro-for-beginners |website=XPATS International |access-date=6 August 2022 |date=26 April 2022 |archive-date=25 June 2024 |archive-url=https://web.archive.org/web/20240625133100/https://xpatsinternational.com/climbing-mount-kilimanjaro-for-beginners/ |url-status=live }}</ref> and the [[United Nations Educational, Scientific and Cultural Organization]]<ref name="UNESCO">{{cite web | url=https://whc.unesco.org/en/list/403 | title=Kilimanjaro National Park | publisher=UNESCO World Heritage Centre | work=World Heritage List | access-date=16 July 2015 | archive-url=https://web.archive.org/web/20120419001216/http://whc.unesco.org/en/list/403 | archive-date=19 April 2012 | url-status=live }}</ref> lists the height of Uhuru Peak as {{convert|5895|m|ft|0|abbr=on}}, based on a [[Ordnance Survey|British survey]] in 1952.<ref name="Digital">{{cite web | url=http://ceur-ws.org/Vol-1142/paper12.pdf | title=The New Digital Orthometric Elevation Model of Kilimanjaro | publisher=CEUR Workshop Proceedings | access-date=16 July 2015 | author=Pascal Sirguey, Nicolas J. Cullen and Jorge Filipe Dos Santos | archive-url=https://web.archive.org/web/20160304084432/http://ceur-ws.org/Vol-1142/paper12.pdf | archive-date=4 March 2016 | url-status=live }}</ref> The height has since been measured as {{convert|5,892|m|ft|abbr=on}} in 1999, {{convert|5902|m|ft|abbr=on}} in 2008, and {{convert|5,899|m|ft|abbr=on}} in 2014.<ref name="Digital"/>

A map of the Kibo cone on Mount Kilimanjaro was published by the British government's [[Directorate of Overseas Surveys]] (DOS) in 1964 based on aerial photography conducted in 1962 as the "Subset of Kilimanjaro, East Africa (Tanganyika) Series Y742, Sheet 56/2, D.O.S. 422 1964, Edition 1, Scale 1:50,000".<ref>{{cite conference | url=http://www.fig.net/resources/proceedings/fig_proceedings/fig2014/papers/ts08b/TS08B_sirguey_cullen_6959.pdf | title=A Century of Photogrammetry on Kilimanjaro | access-date=16 July 2015 | author1=Pascal SRIGUEY | author2=Nicolas J. CULLEN | name-list-style=amp | book-title=Engaging the Challenges – Enhancing the Relevance | year=2014 | conference=FIG Congress 2014 | location=Kuala Lumpur, Malaysia | archive-url=https://web.archive.org/web/20150721085511/http://www.fig.net/resources/proceedings/fig_proceedings/fig2014/papers/ts08b/TS08B_sirguey_cullen_6959.pdf | archive-date=21 July 2015 | url-status=live }}</ref> Tourist mapping was first published by the [[Ordnance Survey]] in England in 1989 based on the original DOS mapping at a scale of 1:100,000, with {{convert|100|ft|m|abbr=on}} contour intervals, as DOS 522.<ref name="Stewart2012">{{cite book | author=Alex Stewart | title=Kilimanjaro: A Complete Trekker's Guide: Preparations, practicalities and trekking routes to the 'Roof of Africa' | url=https://books.google.com/books?id=28N6F2wBSM8C&pg=PA33 | date=23 April 2012 | publisher=Cicerone Press Limited | isbn=978-1-84965-622-1 | page=33 | access-date=4 October 2016 | archive-url=https://web.archive.org/web/20170223185114/https://books.google.com/books?id=28N6F2wBSM8C&pg=PA33 | archive-date=23 February 2017 | url-status=live }}</ref> West Col Productions produced a map with tourist information in 1990, at a scale of 1:75,000, with {{convert|100|m|ft|abbr=on}} contour intervals; it included inset maps of Kibo and Mawenzi on 1:20,000 and 1:30,000 scales respectively and with {{convert|50|m|ft|abbr=on}} contour intervals.<ref name="Stewart2012"/> In recent years, numerous other maps have become available, of various qualities.<ref name=map/>

=== Volcanology ===

The volcanic interior of Kilimanjaro is poorly known because there has not been any significant erosion to expose the [[igneous]] strata that comprise the volcano's structure.<ref name="Preliminary">{{cite journal |doi=10.1017/S0016756800066590 |bibcode=1956GeoM...93..218W |title=Preliminary Notes on the Geology of Kilimanjaro |journal=Geological Magazine |volume=93 |issue=3 |pages=218–228 |last1=Wilcockson |first1=W. H. |year=1956 |s2cid=128393681 }}</ref>

Eruptive activity at the Shira center commenced about 2.5 million years ago, with the last important phase occurring about 1.9 million years ago, just before the northern part of the edifice collapsed.<ref name="NonnottePhilippe"/> Shira is topped by a broad [[high plain]] at {{convert|3800|m|ft|abbr=on}}, which may be a filled [[caldera]]. The remnant caldera rim has been degraded deeply by erosion. Before the caldera formed and erosion began, Shira might have been between {{convert|4,900 and 5,200|m|abbr=on}} high. It is mostly composed of basaltic lavas, with some [[Pyroclastic rock|pyroclastics]]. The formation of the caldera was accompanied by lava emanating from [[Fracture (geology)|ring fractures]], but there was no large-scale [[Explosive eruption|explosive activity]]. Two cones formed subsequently, the [[phonolite|phonolitic]] one at the northwest end of the ridge and the [[diabase|doleritic]] Platzkegel in the caldera center.<ref name="NonnottePhilippe"/><ref name="Preliminary"/><ref>{{cite web |url=https://www.tranquilkilimanjaro.com/kilimanjaro-geology/ |website=Tranquil Kilimajaro |access-date=25 February 2024 |title=Kilimanjaro Geology |archive-date=25 June 2024 |archive-url=https://web.archive.org/web/20240625132954/https://www.tranquilkilimanjaro.com/kilimanjaro-geology/ |url-status=live }}</ref><ref name="JohnBarryDawson">{{cite book | author=John Barry Dawson | title=The Gregory Rift Valley and Neogene-recent Volcanoes of Northern Tanzania | url=https://books.google.com/books?id=Om2oMjXK3R4C&pg=PA56 | year=2008 | publisher=Geological Society of London | isbn=978-1-86239-267-0 | page=56 | access-date=2016-10-04 | archive-url=https://web.archive.org/web/20170223200626/https://books.google.com/books?id=Om2oMjXK3R4C&pg=PA56 | archive-date=2017-02-23 | url-status=live }}</ref>

Both Mawenzi and Kibo began erupting about 1 million years ago.<ref name="NonnottePhilippe"/> They are separated by the Saddle Plateau at {{convert|4400|m|ft|abbr=on}} elevation.<ref name="AnAscentOfKilimanjaro">{{cite journal |doi=10.2307/1780513 |jstor=1780513 |title=An Ascent of Kilimanjaro |journal=The Geographical Journal |volume=61 |issue=1 |pages=1–21 |last1=Gillman |first1=C. |year=1923 |bibcode=1923GeogJ..61....1G }}</ref>{{rp|3}}

The youngest dated rocks at Mawenzi are about 448,000 years old.<ref name="NonnottePhilippe"/> Mawenzi forms a horseshoe-shaped ridge with [[Rock pinnacle|pinnacles]] and ridges opening to the northeast, with a tower-like shape resulting from deep erosion and a [[mafic]] [[dike swarm]]. Several large [[cirque]]s cut into the ring and the largest of these sits on top of the Great Barranco gorge. Also notable are the East and West Barrancos on the northeastern side of the mountain. Most of the eastern side of the mountain has been removed by erosion. Mawenzi has a [[subsidiary peak]], Neumann Tower, {{convert|4425|m|ft|abbr=on}}.<ref name="NonnottePhilippe"/><ref name="Preliminary"/><ref name="JohnBarryDawson"/>

[[File:Kilimanjaro from Amboseli.jpg|thumb|left|Kilimanjaro in March 2012]]

Kibo is the largest cone on the mountain and is more than {{convert|24|km|mi|abbr=on}} wide at the Saddle Plateau altitude. The last activity here, dated to 150,000–200,000 years ago, created the current Kibo summit crater. Kibo still has gas-emitting [[fumarole]]s in its crater.<ref name="NonnottePhilippe"/><ref name="Preliminary"/><ref name="JohnBarryDawson"/> Kibo is capped by an almost symmetrical cone with [[escarpment]]s rising {{convert|180|to|200|m|abbr=on}} on the south side. These escarpments define a {{convert|2.5|km|mile|adj=mid|-wide|abbr=on}} caldera<ref name="Glaciers of Middle East"/> caused by the collapse of the summit.

Within this caldera is the Inner Cone and within the crater of the Inner Cone is the Reusch Crater, which the Tanganyika government in 1954 named after Gustav Otto Richard Reusch, upon his climbing the mountain for the 25th time (out of 65 attempts during his lifetime).<ref>{{cite web | url=http://cvgs.cu-portland.edu/history/biographies/bio.cfm?id=529 | title=Gustav Otto Richard Reusch | publisher=The Center for Volga German Studies at Concordia University | work=Biographies | access-date=16 July 2015 | archive-url=https://web.archive.org/web/20151024111716/http://cvgs.cu-portland.edu/history/biographies/bio.cfm?id=529 | archive-date=24 October 2015  }}</ref><ref>{{cite book | author=Richard Leider | title=The Power of Purpose: Find Meaning, Live Longer, Better | url=https://archive.org/details/The_Power_of_Purpose_2nd_9781605095271 | url-access=registration | date=10 May 2010 | publisher=Berrett-Koehler Publishers | isbn=978-1-60509-527-1 | page=[https://archive.org/details/The_Power_of_Purpose_2nd_9781605095271/page/n26 12] | access-date=4 October 2016 }}</ref> The Ash Pit, {{convert|350|m|ft|abbr=on}} deep, lies within the Reusch Crater.<ref>{{cite web | url=http://volcano.oregonstate.edu/kilimanjaro | title=Kilimanjaro | publisher=Oregon State University | work=Volcano World | date=25 April 2011 | access-date=16 July 2015 | archive-url=https://web.archive.org/web/20150718113556/http://volcano.oregonstate.edu/kilimanjaro | archive-date=18 July 2015 | url-status=live }}</ref> About 100,000 years ago, part of Kibo's crater rim collapsed, creating the area known as the [[Western Breach]] and the Great Barranco.<ref>{{cite book | author=Alex Stewart | title=Kilimanjaro: A Complete Trekker's Guide: Preparations, practicalities and trekking routes to the 'Roof of Africa' | url=https://books.google.com/books?id=28N6F2wBSM8C&pg=PA97 | date=23 April 2012 | publisher=Cicerone Press Limited | isbn=978-1-84965-622-1 | page=100 | access-date=4 October 2016 | archive-url=https://web.archive.org/web/20170223175534/https://books.google.com/books?id=28N6F2wBSM8C&pg=PA97 | archive-date=23 February 2017 | url-status=live }}</ref>

An almost continuous layer of lava buries most older geological features, except exposed [[Stratum|strata]] within the Great West Notch and the Kibo Barranco. The former exposes intrusions of [[syenite]].<ref name="Preliminary"/> Kibo has five main lava formations:<ref name="NonnottePhilippe"/>

* [[Phonotephrite]]s and [[tephriphonolite]]s of the Lava Tower group, on a [[Dike (geology)|dyke]] cropping out at {{convert|4600|m|ft|abbr=on}}, dated to 482,000 years ago.
* Tephriphonolite to phonolite lavas "characterized by rhomb mega-phenocrysts of sodic feldspars" of the Rhomb Porphyry group, dated to 460,000–360,000 years ago.
* [[Phenocryst|Aphyric]] phonolite lavas, "commonly underlain by basal obsidian horizons", of the Lent group, dated to 359,000–337,000 years ago
* [[Porphyry (geology)|Porphyritic]] tephriphonolite to phonolite lavas of the Caldera Rim group, dated to 274,000–170,000 years ago
* Phonolite lava flows with [[aegirine]] [[phenocryst]]s, of the Inner Crater group, which represents the last volcanic activity on Kibo

Kibo has more than 250 [[parasitic cone]]s on its northwest and southeast flanks that were formed between 150,000 and 200,000 years ago<ref name="NonnottePhilippe"/> and erupted [[picrobasalt]]s, [[trachybasalt]]s, [[ankaramite]]s, and [[basanite]]s.<ref name="NonnottePhilippe"/><ref name="Preliminary"/><ref name="JohnBarryDawson"/> They reach as far as [[Lake Chala]] and [[Taita-Taveta County|Taveta]] in the southeast and the Lengurumani Plain in the northwest. Most of these cones are well preserved, except the Saddle Plateau cones which were heavily affected by glacial action. Despite their mostly small size, lava from the cones has obscured large portions of the mountain. The Saddle Plateau cones are mostly cinder cones with terminal effusion of lava, while the Upper Rombo Zone cones mostly generated lava flows. All Saddle Plateau cones predate the last glaciation.<ref name="Preliminary"/>

According to reports gathered in the 19th century from the [[Maasai people|Maasai]], Lake Chala on Kibo's eastern flank was the site of a village that was destroyed by an eruption.<ref name="ShearsonHyland"/>

=== Glaciers ===
[[File:Kilimanjaro dymamics2.jpg|alt=|thumb|Kilimanjaro's glaciers' retreat in 1912–2018]]

Kibo's ice cap exists because Kilimanjaro is a little-dissected, massive mountain that rises above the [[snow line]]. The cap is divergent and at the edges splits into individual glaciers. The central portion of the ice cap is interrupted by the presence of the Kibo crater.<ref name="AnAscentOfKilimanjaro"/>{{rp|5}} The summit glaciers and ice fields do not display significant horizontal movements because their low thickness precludes major deformation.<ref name="TraceElements"/>

Geological evidence shows five successive glacial episodes during the [[Quaternary]] period, namely First (500,000 [[Before Present|BP]]), Second (greater than 360,000 years ago to 240,000 BP), Third (150,000 to 120,000 BP), Fourth (also known as "Main") (20,000 to 17,000 BP), and Little (16,000 to 14,000 BP). The Third may have been the most extensive, and the Little appears to be statistically indistinguishable from the Fourth.<ref>{{cite journal |doi=10.1002/jqs.1222 |title=Quaternary glaciation in Africa: Key chronologies and climatic implications |journal=Journal of Quaternary Science |volume=23 |issue=6–7 |pages=589–608 |year=2008 |last1=Mark |first1=Bryan G. |last2=Osmaston |first2=Henry A. |bibcode=2008JQS....23..589M |citeseerx=10.1.1.529.4209 |s2cid=130605599 }}</ref>

A continuous ice cap covering approximately {{convert|400|km2|mi2|abbr=on}} down to an elevation of {{convert|3200|m|ft|abbr=on}} covered Kilimanjaro during the [[Last Glacial Maximum]] in the [[Pleistocene]] epoch (the Main glacial episode), extending across the summits of Kibo and Mawenzi.<ref name="Kaser"/><ref name="Glaciers of Middle East"/> Because of the exceptionally prolonged dry conditions during the subsequent [[Younger Dryas]] [[stadial]], the ice fields on Kilimanjaro may have become extinct around 11,500 years BP.<ref name="TraceElements">{{cite journal |doi=10.1016/j.quascirev.2014.03.007 |bibcode=2014QSRv...93....1G |title=Deglaciated areas of Kilimanjaro as a source of volcanic trace elements deposited on the ice cap during the late Holocene |journal=Quaternary Science Reviews |volume=93 |pages=1–10 |last1=Gabrielli |first1=P. |last2=Hardy |first2=D. R. |last3=Kehrwald |first3=N. |last4=Davis |first4=M. |last5=Cozzi |first5=G. |last6=Turetta |first6=C. |last7=Barbante |first7=C. |last8=Thompson |first8=L. G. |year=2014 }}</ref> [[Ice core]]s taken from Kilimanjaro's Northern Ice Field (NIF) indicates that the glaciers there have a basal age of about 11,700 years,<ref>{{cite journal | last=Thompson | first=Lonnie G | title=Kilimanjaro Ice Core Records: Evidence of Holocene Climate Change in Tropical Africa | journal=Science | volume=298 | issue=5593 | pages=589–593 | url=http://www.geo.umass.edu/climate/doug/pubs/thompson_etal_sci02.pdf | access-date=16 August 2012 | bibcode=2002Sci...298..589T | year=2002 | doi=10.1126/science.1073198 | pmid=12386332 | s2cid=32880316 | archive-url=https://web.archive.org/web/20120205025226/http://www.geo.umass.edu/climate/doug/pubs/thompson_etal_sci02.pdf | archive-date=5 February 2012  }}</ref> although an analysis of ice taken in 2011 from exposed vertical cliffs in the NIF supports an age extending only to 800 years BP.<ref>{{cite journal |bibcode=2015EGUGA..17.5091U |title=The controversial age of Kilimanjaro's plateau glaciers |journal=EGU General Assembly Conference Abstracts |volume=17 |page=5091 |last1=Uglietti |first1=Chiara |last2=Zapf |first2=Alexander |last3=Szidat |first3=Sönke |last4=Salazar |first4=Gary |last5=Hardy |first5=Doug |last6=Schwikowski |first6=Margit |year=2015 }}</ref> [[African humid period|Higher precipitation rates at the beginning]] of the [[Holocene]] epoch (11,500 years BP) allowed the ice cap to reform.<ref name="TraceElements"/> The glaciers survived a widespread drought during a three century period beginning around 4,000 years BP.<ref name="TraceElements"/><ref name="unabated">{{cite journal |doi=10.1073/pnas.0906029106 |pmid=19884500 |pmc=2771743 |bibcode=2009PNAS..10619770T |title=Glacier loss on Kilimanjaro continues unabated |journal=Proceedings of the National Academy of Sciences |volume=106 |issue=47 |pages=19770–5 |last1=Thompson |first1=L. G. |last2=Brecher |first2=H. H. |last3=Mosley-Thompson |first3=E. |last4=Hardy |first4=D. R. |last5=Mark |first5=B. G. |year=2009 |doi-access=free }}</ref>

[[File:Kibo-großer Gletscher(big glacier).jpg|thumb|left|Vertical margin wall of the [[Rebmann Glacier]] in 2005 with [[Mount Meru (Tanzania)|Mount Meru]], which is {{convert|70|km|mi|0|abbr=on}} away, in the background]]

In the late 1880s, the summit of Kibo was completely covered by an ice cap about {{convert|20|km2|mi2|abbr=on}} in extent with outlet glaciers cascading down the western and southern slopes, and except for the inner cone, the entire caldera was buried. Glacier ice also flowed through the Western Breach.<ref name="Kaser"/><ref name="Glaciers of Middle East">{{cite web | last=Young | first=James A. T. | title=Glaciers of the Middle East and Africa | url=http://pubs.usgs.gov/pp/p1386g/africa.pdf | work=U.S. Geological Professional Survey | publisher=U.S. Department of the Interior | pages=G61, G58, G59 G62 | access-date=16 August 2012 | archive-url=https://web.archive.org/web/20120728083729/http://pubs.usgs.gov/pp/p1386g/africa.pdf | archive-date=28 July 2012 | url-status=live }}</ref> The slope glaciers retreated rapidly between 1912 and 1953, in response to a sudden shift in climate at the end of the 19th century that made them "drastically out of equilibrium", and more slowly thereafter. Their continuing demise indicates they are still out of equilibrium in response to a constant change in climate over the past century.<ref name="Kaser"/>

In contrast to the persistent slope glaciers, the glaciers on Kilimanjaro's crater plateau have appeared and disappeared repeatedly during the Holocene epoch, with each cycle lasting a few hundred years.<ref>{{cite journal | last1=Kaser | first1=Georg | last2=Mölg | first2=Thomas | last3=Cullen | first3=Nicolas J. | last4=Hardy | first4=Douglas R. | last5=Winkler | first5=Michael | title=Is the decline of ice on Kilimanjaro unprecedented in the Holocene? | journal=The Holocene | volume=20 | issue=7 | year=2010 | pages=1079–1091 | issn=0959-6836 | doi=10.1177/0959683610369498| bibcode=2010Holoc..20.1079K |citeseerx = 10.1.1.211.435| s2cid=16945088 }}</ref>{{rp|1088}} It appears that decreasing specific humidity instead of temperature changes has caused the shrinkage of the slope glaciers since the late 19th century. No clear warming trend at the elevation of those glaciers occurred between 1948 and 2005. Although air temperatures at that elevation are always below freezing, solar radiation causes melting on vertical faces. Vertical ice margin walls are a unique characteristic of the summit glaciers and a major place of the shrinkage of the glaciers. They manifest stratifications, [[Ice calving|calving]], and other ice features.<ref name="SinghSingh2011"/> "There is no pathway for the plateau glaciers other than to continuously retreat once their vertical margins are exposed to solar radiation."<ref name="Kaser"/> The Kilimanjaro glaciers have been used for deriving ice core records, including two from the southern icefield. Based on this data, this icefield formed between 1,250 and 1,450 years BP.<ref>{{cite book |doi=10.1016/B0-44-452747-8/00351-3 |chapter=ICE CORE RECORDS &#124; Africa |title=Encyclopedia of Quaternary Science |pages=1220–1225 |year=2007 |last1=Thompson |first1=L.G. |last2=Davis |first2=M.E. |isbn=978-0-444-52747-9 }}</ref>

[[File:Kilimanjaro sunrise at GillmanPoint(1).jpg|thumb|A vertical glacier margin wall as seen from Gilman's Point on the crater rim at sunrise in 1998]]

Almost 85 percent of the ice cover on Kilimanjaro disappeared between October 1912 and June 2011, with coverage decreasing from {{convert|11.40|km2|mi2|abbr=on}} to <{{convert|1|km2|mi2|abbr=on}}<ref>{{cite journal |url=https://iopscience.iop.org/article/10.1088/2752-5295/ad1fd7 |title=Tropical glacier loss in East Africa: recent areal extents on Kilimanjaro, Mount Kenya, and in the Rwenzori Range from high-resolution remote sensing data |first1=Anne |last1=Hinzmann |first2=Thomas |last2=Mölg |first3=Matthias |last3=Braun |first4=Nicolas J |last4=Cullen |first5=Douglas R |last5=Hardy |first6=Georg |last6=Kaser |first7=Rainer |last7=Prinz |journal=Environmental Research: Climate |volume=3 |number=1 |date=2024 |doi=10.1088/2752-5295/ad1fd7}}</ref><ref name="Retreat"/>{{rp|423}} Between 1912 and 1953, there was about a 1.1 percent average annual loss of ice coverage.<ref name="unabated"/> The average annual loss for 1953 to 1989 was 1.4 percent, while the loss rate for 1989 to 2007 was 2.5 percent.<ref name="unabated"/> Of the ice cover still present in 2000, almost 40 percent had disappeared by 2011.<ref name="Retreat">{{cite journal | last1=Cullen | first1=N. J. | last2=Sirguey | first2=P. | last3=Mölg | first3=T. | last4=Kaser | first4=G. | last5=Winkler | first5=M. | last6=Fitzsimons | first6=S. J. | title=A century of ice retreat on Kilimanjaro: the mapping reloaded | journal=The Cryosphere | volume=7 | issue=2 | year=2013 | pages=419–431 | issn=1994-0424 | doi=10.5194/tc-7-419-2013| bibcode=2013TCry....7..419C | doi-access=free }}</ref>{{rp|425}} Ice climber Will Gadd noticed differences between his 2014 and 2020 climbs.<ref>{{Cite web|last=Zeinab|first=Noura Abou|date=15 October 2020|title='Big pieces' of Kilimanjaro 'missing' due to climate crisis, says ice climber Will Gadd|url=https://edition.cnn.com/2020/10/15/sport/will-gadd-ice-climber-climate-change-spt-intl/index.html|access-date=15 October 2020|website=CNN|archive-date=5 October 2024|archive-url=https://web.archive.org/web/20241005154229/https://edition.cnn.com/2020/10/15/sport/will-gadd-ice-climber-climate-change-spt-intl/index.html|url-status=live}}</ref> The glaciers are thinning in addition to losing areal coverage,<ref name="unabated"/> and do not have active accumulation zones; retreat occurs on all glacier surfaces. Loss of glacier mass is caused by both melting and [[sublimation (phase transition)|sublimation]].<ref name="TraceElements"/> While the current shrinking and thinning of Kilimanjaro's ice fields appear to be unique within its almost twelve-millennium history, it is contemporaneous with widespread [[Retreat of glaciers since 1850|glacier retreat]] in mid-to-low latitudes across the globe.<ref name="unabated"/> In 2013, it was estimated that, at the current [[Climate change|rate of global warming]], most of the ice on Kilimanjaro will disappear by 2040, and "it is highly unlikely that any ice body will remain after 2060".<ref name="Retreat"/>{{rp|430}}

The Furtwangler Glacier on Kilimanjaro is a remnant of the ice cap that once covered the mountain. This has retreated dramatically over the last century with over 80 percent glacial retreat. The glacier is named after Walter Furtwangler, who along with Ziegfried Koenig, was the fourth to ascend to the summit of Kilimanjaro in 1912.<ref>{{Cite web|last=Nkonge|first=Peninah|date=15 October 2022|title='Hiking Adventures In East Africa's Tallest Mountains|url=https://sunriseafricasafaris.com/hiking-adventures-east-africa/|access-date=15 October 2022|website=Sunrise Africa Tours and Safaris|archive-date=25 June 2024|archive-url=https://web.archive.org/web/20240625133055/https://sunriseafricasafaris.com/hiking-adventures-east-africa/|url-status=live}}</ref>

A complete disappearance of the ice would be of only "negligible importance" to the water budget of the area around the mountain. The forests of Kilimanjaro, far below the ice fields, "are [the] essential water reservoirs for the local and regional populations".<ref>{{cite journal |url=http://lindseynicholson.org/wp-content/uploads/2011/07/Moelg-et-al.-2013.pdf |title=East African glacier loss and climate change: Corrections to the UNEP article ''Africa without ice and snow'' |first1=Georg |last1=Kaser |first2=Thomas |last2=Mölg |first3=Nicolas J. |last3=Cullen |first4=Douglas R. |last4=Hardy |first5=Michael |last5=Winkler |first6=Rainer |last6=Prinz |first7=Lindsey |last7=Nicholson |name-list-style=amp |journal=Environmental Development |volume=6 |pages=1–6 |access-date=2014-10-09 |doi=10.1016/j.envdev.2013.02.001  |archive-url=https://web.archive.org/web/20141015173745/http://lindseynicholson.org/wp-content/uploads/2011/07/Moelg-et-al.-2013.pdf |archive-date=2014-10-15 |url-status=live }}</ref>

=== Drainage ===
Kilimanjaro is drained by a network of rivers and streams, especially on the wetter and more heavily eroded southern side and primarily above {{convert|1200|m|ft|abbr=on}}. Below that altitude, increased evaporation and human water usage reduce the water flows. The [[Lumi River (East Africa)|Lumi]] and [[Pangani River|Pangani]] rivers drain Kilimanjaro on the eastern and southern sides, respectively.<ref>{{cite book | author=William Dubois Newmark | title=The Conservation of Mount Kilimanjaro | url=https://books.google.com/books?id=0Is9h1vm90AC&pg=PA22 | year=1991 | publisher=IUCN | isbn=978-2-8317-0070-0 | pages=105–106 | access-date=2016-10-04 | archive-url=https://web.archive.org/web/20170223215317/https://books.google.com/books?id=0Is9h1vm90AC&pg=PA22 | archive-date=2017-02-23 | url-status=live }}</ref>

===IUGS geological heritage site===
In respect of it being 'the highest [[stratovolcano]] of the East African Rift that maintains a glacier on its summit', the [[International Union of Geological Sciences]] (IUGS) included 'The Pleistocene Kilimanjaro volcano' in its assemblage of 100 'geological heritage sites' around the world in a listing published in October 2022. The organization defines an IUGS Geological Heritage Site as 'a key place with geological elements and/or processes of international scientific relevance, used as a reference, and/or with a substantial contribution to the development of geological sciences through history.'<ref>{{cite web |title=The First 100 IUGS Geological Heritage Sites |url=https://iugs-geoheritage.org/videos-pdfs/iugs_first_100_book_v2.pdf |website=IUGS International Commission on Geoheritage |publisher=IUGS |access-date=13 November 2022 |archive-date=27 October 2022 |archive-url=https://web.archive.org/web/20221027114156/https://iugs-geoheritage.org/videos-pdfs/iugs_first_100_book_v2.pdf |url-status=live }}</ref>