**1. Introduction**

Few mountains in Europe host classical glaciers at present: The Alps, the Great Caucasus range, the Scandinavian mountains, Polar Ural and the Pyrenees [1]. Apart from them, there are numerous small bodies of firn and ice in other mountain ranges across Europe which are still of a permanent character, with their mass moving down by gravity. Of a special interest are those in the mountains of Southern Europe [2]. They represent the furthest glacial outposts, some of which located at almost subtropical latitudes (41–43°N). Most of them exist well below the present climatic snowline, in places of favourable topography and local climate. The marginal conditions in which they still persist, and their great sensibility on shortterm climate variations, make them perfect natural indicators and objects for climate change studies. The present chapter will focus on small glaciers on the Balkan Peninsula. Here, at present, the southernmost glacial masses of Europe are located [2] (**Figure 1**).

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**Figure 1.** Mountains in Southeastern Europe with present-day small glaciers.

Scientists categorize small sustainable firn and ice features mainly in three types: small cirque glaciers, glacierets and snow patches [3].

Small cirque glaciers and glacierets occupy small sections of Pleistocene glacial cirques (usually just below tall rock walls) and can be considered as remnants of former cirque glaciers, which existed during the termination phases of the Wuermian ice age. On the Balkan Peninsula, these features occupy areas of 0.5–5 ha and have thicknesses in the order of 10–20 m. Moraine ridges have framed their lower ends. Small cirque glaciers have elongated contour, a longitudinal profile with a concave upper part and convex lower section of a tongue shape. Glacierets have simpler longitudinal cross-section (convex or concave or straight), lack of a pronounced tongue-like end and the width is often greater than length [4–6]. The presence of dynamic downward motion of firn-ice mass has been, however, proved in both types [3]. Snow patches on the other hand are not considered glaciers. They are either forms that are not permanent in a long-term sense (for more than several years), or they persist in time, but without conditions for motion. Features of the latter type often occupy karst sinkholes.

On the Balkan Peninsula, the present existence of at least 16 small glaciers has been documented and studied in three of the highest mountains: Pirin (in Bulgaria), Prokletije (mainly in Albania) and Durmitor (in Montenegro) [3–18]. Some specific conditions combine to make them possible to exist 600–800 m below the present position of the climatic snow line (estimated between 2700 m in the Western Balkans and 3200 m in the Eastern Balkans, [12, 19]): (1) altitudes between 1900 and 2600 m a. s. l. that provide for relatively low, annual, and seasonal air and ground temperatures (annual: +1 to +3°C, still too high for glaciers); (2) karstified carbonate bedrock, lightly coloured, with high albedo. It does not get warm too much in summer and allows the drainage of glacier meltwaters during ablation season, thus hindering glacier melt; (3) Shaded locations in former cirques (North or NE aspect, below high rock cliffs); (4) High winter precipitation and great contribution of avalanche and windblown snow in mass accumulation, which allows to effectively double the actual amount of snowfall.

High mountain climate conditions at these altitudes define two seasons in the annual cycle of small glaciers: accumulation season (from November to April) and ablation season (from May to October), and a balance year that can be considered similar to the hydrological year accepted for the region [20]: November 1 to October 31. Autumn (September 15 to October 31) is the best time to observe small glaciers and measure the results of the consecutive mass balance year.
