Glaciologist Gwenn Flowers and her team are studying the Kaskawulsh glacier in southwest Yukon, which is rapidly thinning and losing about half a metre of ice each year due to climate change. The glacier is retreating and cannot compensate for the volume it is losing. The St. Elias mountain range, which crosses Yukon, British Columbia and Alaska, has the largest ice cover in the world outside Greenland and Antarctica. The changes in the region reflect what is happening in other areas, such as the Andes and the Himalayas, where millions of people rely on glaciers for irrigation and drinking water. The more rapid thinning of the big ice in Yukon is already causing dramatic consequences further down the mountains, such as the drying up of Kluane Lake due to "river piracy". The lake was fed by the Slims River, which suddenly drained when the glacier outflow found a new direction to a new river. The lake dropped 1.7 metres that summer and its levels remain low. The changes in the region are an early warning of what climate change could mean for the rest of the planet.