Viewed at a safe distance from small cruise boats or a wooden observation deck, the jagged surface of Argentina’s Perito Moreno shimmers a white-blue.
The glacier, which lures tourists and scientists to Los Glaciares National Park, is one of only a few ice fields worldwide that have withstood rising global temperatures.
Nourished by Andean snowmelt, it’s growing constantly even as it spawns icebergs the size of apartment buildings into a frigid lake, maintaining a nearly perfect equilibrium since measurements began more than a century ago.
“We’re not sure why this happens,” said Andres Rivera, a glacialist with the Center for Scientific Studies in Valdivia, Chile. “But not all glaciers respond equally to climate change.”
Every few years, Perito Moreno expands enough to touch a point of land across Lake Argentina, cutting the nation’s largest freshwater lake in half and forming an ice dam as it presses against the shore.
The water on one side of the dam surges against the glacier, up to 200 feet above lake level, until it breaks the ice wall with a thunderous crash, drowning the applause of hundreds of tourists.
“It’s like a massive building falling all of the sudden,” said park ranger Javier D’Angelo, who saw the rupture in 2008 and 1998.
The rupture is a reminder that while Perito Moreno appears to be a vast, 19-mile-long frozen river, it’s a dynamic icescape that moves and cracks unexpectedly.
“The glacier has a lot of life,” said Luli Gavina, who leads mini-treks across the glacier’s snow fields.
Park information: www.losglaciares.com/en/parque/