World Glacier Inventory — Inventaire mondial des Glaciers (Proceedings of the Riederalp Workshop, September 1978; Actes de l'Atelier de Riederalp, septembre 1978): IAHS-AISH Publ. no. 126, 1980.

Mountain glaciers in the Mediterranean area and in Africa

B. Messerli

Abstract. Few glaciers or glacierets still exist in the Mediterranean area. The snow line between the Alps and the mountains of North Africa and the Near East must be reconstructed with the help of climatic data. The only glaciers in Africa are on Mt Kenya (covering an area of 0.8 km 2 ) , on Kilimanjaro (5 km2) and in the Ruwenzori (5 km2). The median glacier elevation increases from the Ruwenzori (4680 m) to Mt Kenya (4790 m) and to Kilimanjaro (5430 m). A retreat of the ice limits since the last century, or during the present one, can be reconstructed for the glaciers of the Mediterranean area and of East Africa.

Glaciers de montagne dans la région méditerranéenne et en Afrique Résumé. Il existe aujourd'hui encore un certain nombre de petits glaciers dans la région méditerranéenne. Le tracé de la limite des neiges persistantes entre les Alpes et les montagnes de l'Afrique du Nord et du Proche Orient doit être reconstruit à l'aide de données climatiques. Les seuls glaciers d'Afrique sont situés sur le Mt Kenya (superficie 0.8 km2), le Kilimandjaro (5 km2) et le Ruwenzori (5 km2). L'altitude médiane des glaciers s'élève de 4680 m au Ruwenzori, à 4790 m au Mt Kenya et à 5430 m au Kilimandjaro. Il est possible de reconstruire le retrait de la limite des glaces survenue depuis le siècle dernier, ainsi que celui du siècle présent, pour les glaciers de la région méditerranéenne et du Proche Orient.

INTRODUCTION

The inventory of the iMediterranean glaciers is based on our own fieldwork on the young Pleistocene and recent glaciation in the Sierra Nevada of Spain, in the Gran Sasso of Italy, in the Durmitor, Orjen and Lovcen of Yugoslavia, in the Olympics of Greece, in the Ulu Dagh, Ak Dagh, Bey Dagh, Bolkar Dagh, Erciyas Dagh and Kaçkar Dagh of Turkey, in the High Lebanon, Hermon and Sinai" in the Near East and in the High Atlas of Morocco. In accordance with our knowledge, we mapped all the recent glaciers south of the Alps and tried to reconstruct the snow line in this transition zone between Europe and Africa (Messerli, 1967).

The inventory of the African glaciers is derived from fieldwork on Mt Kenya and Kilimanjaro, but also on personal visits and climatological and geomorphological experience in the mountains of North Africa, Tibesti and Hoggar in the Sahara, Simen and Bale Mountains in Ethiopia and Mt Cameroon in West Africa (Messerli and Winiger, 1979). The only African mountains with recent glaciation today are Mt Kenya, Kilimanjaro and the Ruwenzori.

THE MEDITERRANEAN GLACIERS

The few glacier patches in strictly-delimited favourable situations may appear several hundred metres below the regional snow line surface. They are all in especially protected situations against high radiation in deep, mostly northern oriented summit cirques. Furthermore they may be fed by snow slides and avalanches. The reconstruction of the regional snow line is therefore very problematic. Regarding these difficulties and considering the small number of existing glaciers, we tried to reconstruct an approximate snow line based on the temperature of the warmest summer month, the precipitation and circulation pattern and the orographic situation. The applied

197

198 B. Messerli

methods are discussed in Messerli (1967). The margin of error can be more than 200 m and therefore permits only a very rough classification of the Mediterranean mountains (Fig. 1, Table 1).

THE GLACIERS OF EAST AFRICA

From our own fieldwork and from the latest maps known to us we tried to determine the altitude of the glacier tongue and to calculate the median glacier elevation. For Mt Kenya, our work was based on the high quality map 1:5000 (1967, field survey 1963), for Kilimanjaro we had only the schematic drawing 1:30480 (Sampson, 1971) and for the Ruwenzori we used the map 1:25 000 (1970, field revised 1968). From these documents we tried to draw for the three mountains a map of the glaciation at the scale 1:25 000 (Figs. 2 to 4). Although the maps vary temporally between 1963 and 1971 and the quality of the field surveys are quite different, they show in a general comparison glaciologically and climatologically important and interesting facts, which are summarized in Table 5.

The climatic differentiation of the three mountain systems is clearly shown: the Ruwenzori get more precipitation from the west, compared with the two other mountains (Flohn, 1959 and 1975). This fact is shown in the deep-reaching glaciers (Whittow et al, 1963; and Lichtenegger and Lichtenegger, 1978). Mt Kilimanjaro undergoes more arid conditions than Mt Kenya. Therefore the glaciation rises higher (Downie, 1964; Sampson, 1971 and 1974). The relief of the young volcano, which is only slightly eroded may play a certain role in comparison with the deep dissection on Mt Kenya and the Ruwenzori (Baker, 1967; Messerli and Winiger, 1979).

RECENT CHANGES IN THE MEDITERRANEAN GLACIERS

In the western part of the Mediterranean we described the changes of the so-called 'southernmost glacier of Europe' in the Corral of Veleta in the Sierra Nevada. Before 1880, there was a small glacier, 250 m long and 580 m wide. The retreat began at the end of the last century and today it is only a small firn patch or ice field (Messerli, 1965).

In the eastern part of the Mediterranean we have different reports of the glacier on Erciyas Dagh. With the descriptions of 1902, 1930 and 1962 we can reconstruct the retreat of the ice and the increasing cover by weathered material (Messerli, 1964).

Similar data are available from other mountains of the Mediterranean area (Messerli, 1967), showing this general decrease of glaciation since the last century or the beginning of the present one.

RECENT CHANGES IN THE GLACIERS OF EAST AFRICA

The measurements on the Lewis Glacier of Mt Kenya in the year 1934 (Troll and Wien, 1949 with map 1:13 333)were repeated in 1974 (Caukwell and Hastenrath, 1977 with map 1:2500).

The state of the glacier during the late 1800s and the early decades of the twentieth century is documented by photographs, sketches and expedition reports. The Lewis Glacier, as the largest ice body of Mt Kenya, is certainly one of the best known glaciers of the Tropics and therefore of special interest for studying the mass and heat budget and long-term changes.

In 1976 we made some field observations on the whole massif without measure­ments, but based on the excellent map 1:5000 of 1963. The results are shown in Fig. 5. Although the observations are incomplete and not very exact, a remarkable retreat of the ice within these 13 years can be seen.

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FIGURE 2. The glaciers of Mt Kenya - generalized situation 1963 (see Fig. 4 for legend and Table 2).

TABLE 2. Glaciers of Mt Kenya, 1963 (see Fig. 2)

Name of glacier

Lewis Tyndall Gregory Cesar Darwin Krapf Kolbe Northey Josef Forel Heim Diamond Melhuish

Total

No. (Fig. 2)

1 2 3 4 5 6 7 8 9

10 11 12 13

80ha =

Surface [ha]

39 10 8 4 4 3 3 2 2 2 1 1 1

0.8 km2

Orientation

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SW N

NE NE

N W

SW SW

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Glacier tongue elevation

[m]

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Median glacier elevation

[m]

4790 4640 4800 4700 4750 4750

— 4780 4630 4960 4800 5060 4810

* There exists a lower glacier tongue of another glacier in this area or cirque.

Mountain glaciers in the Mediterranean area and in Africa 2 0 3

FIGURE 3. The glaciers of Kilimanjaro (Kibo) - schematic situation 1971 (see Fig. 4 for legend and Table 3).

TABLE 3. Glaciers of Kilimanjaro, 1971 (see Fig. 3)

Name of glacier

Northern Icefield

Credner Kersten Decken Heim Big Breach Drygalski Little Penck Great Penck Rebmann Little Breach Furtwangler Ratzel Diamond Arrow Ice Cathedral

No. (Fig. 3)

1 2 3 4 5 6 7 8 9

10 11 12 13 14 15 16

Surface [ha]

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Orientation

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Glacier tongue elevation

[m]

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Median glacier elevation

[m]

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Total 509 ha « 5 km2

204 B. Messerli

FIGURE 4. The glaciers of the Ruwenzori - situation 1968.

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TABLE 5. Summary statistics for glaciers in East Africa

Mountain No. of glaciers

Mean elevation of glacier tongues

[m]

Mean of median glacier elevations

[m]

Mt Kenya

Kilimanjaro

Ruwenzori

13

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30

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200 Glacier tongue: difference in altitude from 1963 to Î97S

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FIGURE 5. Glaciers of Mt Kenya, recent changes.

For Mt Kilimanjaro, the older maps of Meyer (1900) and Klute (1920) together with the somewhat schematic statement of Sampson (1971) were taken into considera­tion. These ice limits were compared with those of 1976 by an overflight and a partial field reconnaissance (Fig. 6).

Several descriptions of ice retreat are known from the Ruwenzori since the first pictures were made by the Duke of Abruzzi (Savoyen, 1909), see figs. 2 and 18 in Whittow <?<-«/. (1963).

To sum up, the glaciers of the equatorial mountains of East Africa show an ice retreat of essential significance comparable to the Alps and to the Mediterranean. However, this finding must be subjected in future to closer examination and must be based on more data.

208 B. Messed i

FIGURE 6. Glaciers of Kilimanjaro (Kibo) - recent changes.

THE PROBLEMS OF CLIMATE AND CLIMATIC CHANGE

Figure 7 shows the horizontal and vertical zonation of the mountains from the Mediterranean to the equator and the change from the early Pleistocene to the present time. The more detailed climatic interpretation can be found in Messerli and Winiger (1979).

To sum up, it shows the conditions for glaciers in the transition zone from a seasonal to a diurnal type of climate. Although a recent hypothetical snow line would be interrupted over the arid zone, due to the absence of humidity (Messerli, 1973), snow is not unknown in the central Saharian mountains, nor in the Sinaï and the Ethiopian mountains, as listed in Table 6.

Acknowledgements. We are greatly indebted to the Swiss National Science Foundation for their financial support of the fieldwork.

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TABLE 6. Frequency of snowfall (Messerli and Winiger, 1979)

Area

High Atlas Antiatlas Sinaï Hoggar

Tibesti

Simen Mts Bale Mts Mt Kenya \ Kilimanjaro > Ruwenzori /

Latitude

31°N 30°N 28°N 23°N

21 °N

13°N 7°N

0°N

Altitude of snowfall area

above 1000 m above 1500 m above 2000 m above 2500 m

above 3000 m

above 4000 m above 4000 m

above 4000 m

Frequency

annual annual annual (?) every 3rd year (?) every 7th year (?) annual annual

annual

Season

winter winter winter winter

winter

rainy period rainy period

in all seasons

MAPS

Maps ofMt Kenya Mt Kenya, 1:5000 and 1:10 000, published 1967, photogrammetric survey 1963. Research Scheme

Nepal Himalaya: Kartographische Anstalt Freytag-Berndt, Vienna. Mt Kenya, 1:25 000, published 1964: Directorate of Overseas Surveys and Survey of Kenya,

Nairobi. Der Lewisgletscher am Mt Kenya, 1:13 333, published 1949, fieldwork 1934. In TroË, C. and

Wien, K. (1949) Der Lewisgletscher am Mount Kenya. Geogr. Ann. 31, 257-274. Lewis Glacier, Mount Kenya, 1:2500, published 1977, fieldwork 1974. In Caukwell, R. A. and

Hastenrath, S. (1977) A new map of Lewis Glacier, Mount Kenya. Erdkunde 31, no. 2, 85-87.

Maps ofMt Kilimanjaro Kilimanjaro, East Africa, 1:100 000, published 1965, aerial photography from 1950,1958 and

1961 with additional information 1963: Government of the United Republic of Tanzania. Kilimanjaro District, 1:125 000, published 1967 : Government of the United Republic of

Tanzania. Karte der Hochregion des Kilimandscharo Gebirges, 1:50 000, published 1920, fieldwork 1912.

In Klute, F. (1920) Ergebnisse der Forschungen am Kilimandscharo 1912: Reimer, Berlin. Der Kilimandjaro, 1:100 000, published 1900, fieldwork 1887-1898 by H. Meyer: Reimer, Berlin. Kilimanjaro - geology, volcanology and glaciology, 1:30 480, published 1971. In Sampson,

D. N. (1971) Guide Book to Mt Kenya and Kilimanjaro: Mountain Club of Kenya, Nairobi.

Map ofMt Ruwenzori Central Ruwenzori, 1:25 000, published 1970, aerial photography 1955 with field revision 1968:

Department of Lands and Surveys, Uganda.

REFERENCES

Baker, B. H. (1967) Geology of Mount Kenya. Report no. 79, Geological Survey of Kenya, Nairobi. Bergstroem, E. (1955) British Ruwenzori Expedition 1952: glaciological observations -

preliminary report. J. Glaciol. 2, no. 17, 469-477. Caukwell, R. A. and Hastenrath, S. (1977) A new map of Lewis Glacier, Mount Kenya. Erdkunde

31, 85-87. Downie, C. (1964) Glaciation of Mount Kilimanjaro. Bull. Amer. Geol. Soc. 75, 1-16. Flohn, H. (1959) Equatorial westerlies over Africa, their extension and significance. Bonn.

Met. Abh. 5, 36-48. Flohn, H. (1975) Tropische Zirkulationsformen im Lichte der Satellitenaufnahmen.

Forschungsber. d. Londes Nordrhein-Westfalen, Nr 2448, Opladen. Geilinger, W. (1930) Der Kilimandjaro: Verlag H. Huber, Bern and Berlin. Heinzelin, de J. (1953) Les stades de Recession du Glacier Stanley occidental. Explor. Pare.

Nat. Albert, 2nd series, no. 1,1-25. Klute, F. (1920) Ergebnisse der Forschungen am Kilimandscharo 1912: Reimer, Berlin.

Mountain glaciers in the Mediterranean area and in Africa 2 1 1

Lichtenegger, J. and Lichtenegger, B. (1978) In der Wetterkiiche des Ruwenzori. Die Alpen, Schweizer Alpen-Club 54, no. 3, 119-126.

Messerli, B. (1964) Der Gletscher am Erciyas Dagh und das Problem der rezenten Schneegrenze im anatolischen und mediterranen Raum. Geogr. Helv. 19, no. 1,19-34.

Messerli, B. (1965) Beitràgezur Géomorphologie der Sierra Nevada (Andalusien): Juris Verlag, Zurich.

Messerli, B. (1967) Die eiszeitliche und die gegenwartige Vergletscherung im Mittelmeerraum. Geogr. Helv. 22, no. 3, 105-228.

Messerli, B. (197 3) Problems of vertical and horizontal arrangement in the high mountains of the extreme arid zone (central Sahara). Arct. Alp. Res. 5, 139-147.

Messerli, B. and Winiger, M. (1979) The mountains of the Sahara and the Nile. In The Sahara and the Nile: Balkema Publishers, Rotterdam.

Meyer, H. (1900) Der Kilimandjaro: Reimer, Berlin. Sampson, D. N. (1971) Kilimanjaro, the geology, volcanology and geoecology. In Guide Book to

Mt Kenya and Kilimanjaro (edited by J. Mitchell), pp. 155-171: Mountain Club of Kenya, Nairobi.

Sampson, D. N. (1974) The geology, volcanology and glaciology of Mt Kilimanjaro. Tanzania Notes Rec. no. 64, 118-125.

Savoyen, L. A. von, (1909) Der Ruwenzori: Brockhaus, Leipzig. Troll, C. and Wien, K. (1949) Der Lewisgletscher am Mt Kenya. Geogr. Ann. 31, 257-274. Whittow, J. B., Shepherd, A., Goldthorpe, J. E. and Temple, P. H. (1963) Observations on the

glaciers of the Ruwenzori./. Glaciol. 4, no. 35, 581-616.