 One major concern is the increased risk of Glacial Lake Outburst Floods ( GLOF ) , which have in the past had great effect on lives and property . Glacier meltwater left behind by the retreating glacier is often held back by moraines that can be unstable and have been known to collapse if breached or displaced by earthquakes , landslides or avalanches . If the terminal moraine is not strong enough to hold the rising water behind it , it can burst , leading to a massive localized flood . The likelihood of such events is rising due to the creation and expansion of glacial lakes resulting from glacier retreat . Past floods have been deadly and have resulted in enormous property damage . Towns and villages in steep , narrow valleys that are downstream from glacial lakes are at the greatest risk . In 1892 a GLOF released some 200 @,@ 000 m3 ( 260 @,@ 000 cu yd ) of water from the lake of the Glacier de Tête Rousse , resulting in the deaths of 200 people in the French town of Saint @-@ Gervais @-@ les @-@ Bains . GLOFs have been known to occur in every region of the world where glaciers are located . Continued glacier retreat is expected to create and expand glacial lakes , increasing the danger of future GLOFs . 
