Recent global climatic changes result in an intensive melting and retreat of glaciers in the majority of high mountains all over the world. Melting water of glaciers influences runoff regime changes of water streams and causes the overfilling and outburst of lakes.
One of the most dangerous localities (Petrov Lake) is situated in Ak-Sijrak massive, Tien-Shan, Kyrgyzstan. Risk analyses from the hydrology, glaciology, geomorphology and geophysics point of view were carried out here.