14/08/2018
Climate change has turned Peru's glacial lake into a deadly flood timebomb
Nestled beneath the imposing white peaks of two glaciers in Peru’s Cordillera Blanca, the aquamarine Lake Palcacocha is as calm as a millpond. But despite its placid appearance it has become a deadly threat to tens of thousands people living beneath it as a result of global warming.
A handful of residents of Huaraz, the city below the lake, can recall its destructive power. In 1941 a chunk of ice broke away from the glacier in an earthquake, tumbling into the lake. The impact caused a flood wave which sent an avalanche of mud and boulders cascading down the mountain, killing about 1,800 people when it reached the city.
Today the lake is even more potentially dangerous, swollen with glacial meltwater like an almost-overflowing bathtub. A temperature rise of 0.5-0.8C between the 1970s and the 2000s has seen a third of Peru’s ice caps vanish in the last four decades.
The city’s population has grown too. With more than 150,000 inhabitants, today Huaraz is about 15 times larger than it was during the last deadly landslide.
Flood wave modelling by the University of Texas shows how a breakaway chunk of glacier could displace up to 15bn litres of meltwater from the 70-metre deep, mile long (1.7km) lake, propelling a wave of up to 30 metres over a ridge of rocks and down the mountain.
“According to the authorities’ estimates, even if you were able to warn the people, there could still be about 20,000 fatalities,” he adds.
The people would have 30 minutes to evacuate, says Cesar Florez, a risk management specialist for the region’s government and the man ultimately responsible for the people’s safety.
For the poor, largely indigenous farmers in the verdant mountains around the ice caps, the problem is not too much water but too little. The Andean country is home to 70% of the world’s tropical glaciers and as they gradually ebb away, a water crisis looms. Climate change has made the weather unpredictable and the unseasonal melting of the glaciers has thrown the farmers’ existence into jeopardy.