Rangers working at Bernardo O’Higgins National Park, Chile’s largest protected area, located in the Magallanes region, 2,000 kilometres southeast of Santiago, were undertaking a routine patrol when they discovered that the lake had disappeared, leaving behind a dried-up basin containing a few chunks of glacial ice and three wide cracks. During the rangers’ previous visit to the area, the lake had a surface area of more than 100,000 square metres and was up to 30 metres deep.

‘In March, we patrolled the area and everything was normal,’ said Jose Romero of Chile’s National Forestry Service. ‘We went again in May and the lake had disappeared.’ Initially, they thought that the water had simply drained away into the three large fissures, which may have been caused by an earthquake, but global warming was later put forward as the cause.

After surveying the lake from a naval aircraft, scientists suggested that glacial meltwater may have raised the lake to such a level that part of a glacier that was acting as a dam gave way, allowing the water to flow into a nearby fjord and out to sea, said Andres Rivera, a glaciologist with Chile’s Centro de Estudios Científicos.

‘On one side of the Bernardo glacier one can see a large hole or gap, and we believe that’s where the water flowed through,’ he said. The advance and retreat of glaciers is part of the normal dynamics of Patagonia, but climate change was distorting the process, Rivera said. ‘This would not be happening if the temperature had not increased.’

September 2007