A new study has revealed just how much water is locked away in the world's glaciers – and the devastating consequences if it were all released into the oceans.Researchers estimate that glaciers outside the vast ice sheets of Greenland and Antarctica contain around 150,000 cubic kilometres of ice.If every one of these glaciers melted completely, it would raise global sea levels by more than 12 inches (32.3cm).Some glaciers are already disappearing at an alarming rate as global temperatures rise, with those in the mountains among the clearest signs of a warming planet.Glaciers in regions such as the Alps, Andes and Himalayas have suffered dramatic losses in recent decades as warmer air melts ice faster than it can be replaced by snowfall.The researchers said knowing exactly how much ice glaciers contain is crucial for predicting how they will respond to a warming climate.'We must move quickly,' said researcher Niccolò Maffezzoli, from Ca' Foscari University of Venice.'Glaciers at midlatitudes, including those in the Alps, are expected to disappear within the next few decades.' In one example the Geikie Plateau in eastern Greenland (pictured) was found to contain almost twice as much ice as previously estimated, with glaciers there reaching up to 2km thick