The vast tarpaulin unravels, gathering speed as it bounces down the Presena glacier in northern Italy over the glinting snow: summer has arrived, and 100,000 square metres of the Alpine giant are being covered to protect if from global warming. Once ski season is over and the cable cars hang silent, conservationists race to stop the melting by using white coverings which block the suns rays. The Presena glacier, located on the border between the Lombardy and Trentino Alto Adige regions, has lost over a third of its volume since 1993.