Indicators for modern and recent climate change in the highest mountain areas of Bulgaria

The highest Bulgarian mountains Rila (2,925 m a.s.l.) and Pirin (2,914 m a.s.l.) provide virgin mountain landscapes, intensive natural processes and a sharp sensitivity on natural and human impacts. The present paper focuses on the existing natural indicators for changes in climate during the last few centuries in the areas around the highest peaks Musala (the Rila Mountains) and Vihren (the Pirin Mountains), and the accent is put on the past and present existence of embryonic glacier forms. Dynamics of perennial ice bodies in the Pirin and the newly found fresh moraine ridge on the bottom of the Ledeno ezero Lake (the highest lake in the Rila Mts.) as well as the data from instrumental and historical records suggest a general trend of warming since the first two decades of the 20th century, especially expressed in the last 30 years. Inter-annual size variations of perennial ice bodies are found to be closely related to fluctuations of air temperature. Regional comparative studies show that perennial ice bodies in Bulgarian mountains are less sensitive to slight climate fluctuations than some other similar features in the Carpatho-Balkan area. Proper interpretation of these and future research results requires their incorporation in regional studies within the entire Carpatho-Balkan area.