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Yevgeniy A. Zolotarev1 and Yevgeniy G. Kharkovets*2 1 Senior scientist of the Laboratory for Remote Sensing, Department of Cartography, Faculty of Geography, M.V. Lomonosov Moscow State University 2 Research Associate of the Laboratory for Remote Sensing, Department of Cartography, Faculty of Geography, M.V. Lomonosov Moscow State University e-mail [email protected] * Corresponding author GEOGRAPHY EVOLUTION OF THE ELBRUS GLACIATION 13 SINCE THE MID XIX CENTURY UNDER CHANGING CLIMATE. KEY FINDINGS OF THE GLACIO-CARTOGRAPHICAL MONITORING ABSTRACT INTRODUCTION Changes in the area and volume that have Numerous studies conducted recently been occurring from the middle of the XIX by climatologists suggest global climate century within the largest in Europe Elbrus warming, which started in the second half of glaciation were studied using lichenometry the XX century as a result of greenhouse gases and digital cartography methods. There were effect. A number of global climate warming cyclical, approximately 55 years long, frontal models have emerged in Russia and the fluctuations of glaciers Bolshoi Azau (the world [World..., 2003; Climate Change, 2001]. largest Elbrus glacier) and Dzhankuat (which Mountain glaciers are sensitive to climate is representative of all Central Caucasus change. Increase in global temperatures glaciation). should affect their regimes and parameters, specifically, the area and volume. This hypothesis Quantitative data on changes in the area and can be tested through cartographic and aerial- volume of the Elbrus glaciation indicated that satellite monitoring of the largest in Europe the greatest rates of its retreat coincided with Elbrus glaciation which physical surface exceeds the 1850–1887 period. Beginning in 1887, 140 km2. The monitoring of this glacier has the area reduction was occurring practically been conducted for over a century – from the evenly through time while the decrease in its end of the XIX century to the present time. volume has even slowed down. These facts suggest that global climate warming, which THE FRONT FLUCTUATIONS – alternated with short-term cooling periods, THE GLACIER’S RESPONSE began in the middle of the XIX century after TO CLIMATE CHANGE the end of the Little Ice Age. The warming was most likely due to natural rather than Russian Academician G. Abich [Abich, 1875] anthropogenic causes. has established a foundation for long-term observations of some Elbrus glaciers. These KEY WORDS: Elbrus glaciation, global observations are crucial in defining the warming, digital mapping. glaciers’ response to climate change. In 1849 known benchmark near the city of Pyatigorsk. He did not expect to return to the area in the future and limited his studies to the use of angular measurements with a portable sextant to draw general boundaries of the glacier (Fig. 1). This drawing was made from GEOGRAPHY a point located at a well-marked rocky ledge of Mt. Terskolak’s slope above the forest level 14 across from a modern hotel Cheget. During his second visit to the glacier in September 17, 1873, G. Abich found the retreating glacier (Fig. 2). He made the same barometric leveling using the same instrument and benchmark. Different environmental conditions (atmospheric pressure and temperature) in 1873 compared Fig. 1. Location of the Bolshoi Azau glacier to 1849 resulted in a different end moraine tongue on October 21, 1849. Picture by G. Abich elevation measurement (2317 m). G.Abich [Abich, 1875]. accepted this measurement as the final result. The glacier linear retreat from 1849 and 1873, G. Abich made two trips to the to 1873 was measured at 180 m. The third Bolshoi Azau glacier. During his first trip, G. measurement taken by G. Abich was the Abich found that the glacier had intruded difference in the elevations of the foot of the on a mature pine forest. This fact was later moraine line at the glacier end in 1849 and accepted as a fundamental evidence of the elevation of the point of the upper apex the glaciation expanse in the Central end abutted against a more ancient end-lateral Caucuses in the middle of the XIX century moraine covered with mature pine forest. [Tushinski, 1958]. It was assumed that the This difference appeared to be 37,5 m. The glacier’s was at a well defined moraine line moraine slope of such relative height exists at the bottom of the river Azau valley at only in the area of the lower station of the 2295–2300 m elevation in the vicinity of cable-way “Elbrus”. the present-day M.V. Lomonosov Moscow State University (MSU) Elbrus station. There The difference in the elevation of the moraine were no cartographic surveys in Elbrus prior crest and the low water line of the river Azau to 1887 and many researchers of that time in the vicinity of the MSU Elbrus station is [Dinnik, 1890; Mushketov, 1882; Salatskyi, 27 m. Therefore, the glacier could not be 1866] provided contradicting assessments located there in 1849. of the spatial position of the glacier. Such assessments are hard to interpret and reconcile without G. Abich’s data. G. Abich’s work, for some reason, still remains unknown to most researchers and, therefore, deserves a detailed presentation especially of its parts related to the Bolshoi Azau glacier. G. Abich conducted thorough studies of the Bolshoi Azau glacier tongue fluctuations in 1849–1873 using instrumental observations. He defined Fig. 2. Location of the Bolshoi Azau glacier the glacier’s elevation (on October 21 1849) tongue on October 17, 1873 Picture by G. Abich at 2322 m from barometric leveling and a [Abich, 1875]. We found the point from which G.Abich made maps describe the exact location of the his drawings of the glacier in 1849 and 1873 glacier tongue. These maps are a 1:42000 showing the end moraine line in front of the scale topographic map compiled from glacier. A phototheodolite survey conducted the 1887–1890 Corps of Topographical from this point in August 1981 showed well Engineers surveys and a 1:20 000 scale preserved traces of recent glaciation. However, map compiled from the data of the 1911 from this point, the end moraine line can’t phototheodolite survey by G. Burmester GEOGRAPHY be seen in the vicinity of the MSU station (it [Burmester, 1913]. is obstructed by the river Garabashi mudflow 15 cone); but the end moraine line in the Elevation benchmark systems of these maps vicinity of the cable-way “Elbrus” is well visible. should be reconciled with the modern map Furthermore, it was the far most moraine end compiled from the phototheodolite survey line where a buried pine was found in 1968; conducted during the International Geophysical the analysis showed that this tree’s annual rings Year (IGY). I.A. Labutina (1968) determined the growth is similar to that of pines appeared elevations of the 1991 map to be 20 m lower in the Azau valley in the first half of the XVII than that of the modern map. Therefore, the century. Modern elevation of the foot of this elevation of the end of the ice-flow of the line at the bottom of the valley is 2315 m, which Boshoi Azau glacier in 1911 was actually 2345 corresponds well with G. Abich’s measurement m (or 2325 m on the G. Burmester’s map). This of 2317 m. These data are sufficient for a also corresponds well with the actual glacier’s precise determination of the spatial location location. The 1911 map shows the glaciers of the end of the ice-flow of the Bolshoi Azau tongues at approximately 70–80 m higher than glacier in 1849 (Fig. 3). the waterfall of the river Malya Azau in the canyon. The modern map shows the elevation Later research activities of the end XIX – of 2345 m, which is 75 m higher than the beginning XX centuries documented by elevation of the same waterfall. Fig. 3. End moraine in the mid. XIX century at the bottom of the Azau river valley. Phototheodolite image taken on July 15, 1981. be obtained by overlaying the 1887 and 1957 maps, which excludes distortion caused by dead ice near the glacier tongue. This elevation is 2330 m. On the photo taken on August 5, 1890 by A.V. Pastuhov (1893), the location of the glacier’s front at the GEOGRAPHY end of the lava line, which some time ago had blocked the Azau canyon, can be seen 16 clearly (Fig. 4). It is also helpful to review observations of other investigators According to 1881 N.I. Dinnik (first after G. Abich to visit the glacier in 1881, but who unfortunately did not conduct any instrumental measurements), the lower part of the ice-flow ended with a steep slope crossed by cracks; the right part of the ice-flow was adjacent to the open rocks which were at about 2327 m Fig. 4. The tongue of the Bolshoi Azau glacier. elevation from the low river level. In 1911, Image by A.V. Pastuhov on August 5, 1890. G. Burmester described the glacier as growing or as about to be ready to transition The 1887 and modern (of the Elbrus southern to the growing phase. The evidence of that slope) maps benchmark systems correspond were: a steep glacier’s front, absence of the well with each other. Therefore, the 1887 end moraine, intense cracking of the entire Bolshoi Azau ice-flow end elevation can glacier below the icefall, and the presence Fig. 5. The tongue of the Bolshoi Azau glacier. Phototheodolite image by A.V. Blryuhanov. August 1958. GEOGRAPHY 17 Fig. 6. The tongue of the Bolshoi Azau glacier. Phototheodolite image by Ye.A. Zolotarev. August 31, 2002. of a surface swell wave sliding between A distinct feature of the glacier retreat is a 2600 and 2700 m elevation.

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