Last millennium glacier variations and four centuries climate change in Elbrus area, Caucasus, Russian Federation

In cooperation withVincent Jomelli2, Zolotarev3, Irina Seinova4, Natalia Volodicheva3 and Aleksandr Oleinikov3.
1Institute of Geography RAS, Moscow, Russia; 2 CNRS-IRD GREAT ICE MSE, Montpellier, France; 3 Moscow State University, Russia

Moraines of Elbrus area were studied using tree-ring analysis and lichenometry. Six new control points for Rhizocarpon section Rhizocarpon obtained in 2004 on the moraines of Baksan valley, agree in general with the data reported previously by Serebryanny et al. (1984) and Seinova & Zolotarev (2001). We propose a new version of the growth curve, based on 55 surfaces ranging from 3 to 700 years old, which is valid for Ebrus area as well as for Central Caucasus (FIG ). Although there are three control points older than 700 years, they contradict each other and are not used so far for the growth curve construction. The oldest one reported Serebryanny et al. (1984) for the moraine of Khalde glacier (3360+/- 90 14Cyears BP) is probably too old to be used for lichenometry (FIG). We also applied an alternative approach for growth curve construction based on a combination of extreme value theory and Bayesian theory (FIG.) (Naveau et al., 2005, Jomelli, et al., 2005; Cooley et al., 2005), in order to estimate correctly the standard error of the lichenometric dates. We used the new growth curves to re-estimate the age of moraines of Elbrus area and provide the statistical error estimates of the datings.Minimum tree-ring dates were obtained for several moraines of Bolshoy Azau, Terskol and Schkhelda glaciers. The tree-ring dates of moraines of Terskol glacier (1800s, 1850s and 1880s) are in a good agreement with the lichenometric and historical data. The age of the oldest trees growing on an end moraine of Bolshoy Azau glacier (AD1614) brings evidence that the older lateral moraine, which terminates at the lower elevation and was previously dated as 17th century (Tushinsky, 1958, 1963; Baume et al., 1998) is in fact older than 17th century and most probably even older than 13th century, judging by the lichenometric age of the end moraine mentioned above.Temperature sensitive, well-replicated ring width pine chronology (1614-2004) was constructed using the trees growing on the floor of Bolshoy Azau valley in the vicinity of the glacier to estimate climatic changes in the area during the last four centuries.

Fig. 1 Fig. 2
Photo by A. Oleynikov Photo by V. Jomelli

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