Melting ice in southern Chile caused a glacial lake to swell and then empty suddenly, sending a "tsunami" rolling through a river, a scientist said Thursday. No one was injured in the remote region.
Glacier scientist Gino Casassa said the melting of the Colonia glacier, which he blamed on rising world temperatures, filled the Cachet Lake and increased pressure on the ice sheet.
The water bored a 5-mile tunnel through the glacier and finally emptied into the Baker River on April 6.
"The remarkable thing is that the mass of water moved against the current of the river," Casassa told The Associated Press by telephone from the Center for Scientific Studies in the southern city of Valdivia. "It was a real river tsunami."
The lake was nearly full again by late Wednesday, he said.
Casassa said temperatures were unusually high during the recent Southern Hemisphere summer.
"This is a phenomenon that occurs periodically during the summer season, caused by the melting of large masses of ice that swell some lakes," he said. "The basic cause is global warming."
The Tempano glacial lake in Chile's Bernardo O'Higgins National Park abruptly disappeared last year, and has since recovered just some of its former volume.
Park rangers were stunned to find a 130-foot deep crater where a large lake had been.
Scientists blamed warming for that disappearance as well. They suggested the melting of nearby glaciers raised the lake's level to the point where the increased water pressure caused part of a glacier acting as a dam to give way.
The advance and retreat of glaciers is part of Earth's normal climate dynamics, but climate change was distorting the process, Andres Rivera, a glaciologist with the Center for Scientific Studies, said at the time. "This would not be happening if the temperature had not increased."