. >> reporter: jean pierre fasson explained how rapid melting caused by warmer temperatures is makingg 24 inches per day. >> it's a lot. for a glacier, it's a lot. >> reporter: fasson is in charge of mountain safety in this area which includes the picturesque tourist destination of courmayeur, where folks are not in danger but are watching closely. >>> when do you think this might happen? >> you have to call god because you cannot say when it falls. >> reporter: but fasson says the culprit is clear. climate change. >> the great problem for the glacier is not one day of high temperatures. instead, is the continuous of high temperatures night and day. >> reporter: up here on mont blanc at an elevation of more than 11,000 feet, we got a closer look at these glaciers. massive frozen rivers of ice. there are about 30 glaciers here on the italian side of mont blanc and all of them are melting. in fact, in the last 50 years, italian glaciers have lost about 40% of their mass, and this is a global problem. ♪ >>> melting glaciers have led saearing ice sheets. >> that is ach the overnight news