There is a lake high in the mountains that has been measured at as much as 34 times the volume it held just half a century ago. Lying below all that water and the natural moraine that prevents it from rushing downstream are over 50,000 people living in the path of a potential flood.
The lake is named Palcacocha, set high in the beautiful Cordillera Blanca of the Peruvian Andes and the town below is Huaraz, a bustling hub city with over 120,000 inhabitants. The threat many of them live with is a phenomenon called glacial lake outburst flooding (GLOF), which can be triggered by any number of events, including unpredictable incidents like earthquakes or big hunks of ice calving off an adjacent glacier into the lake.
The latter happened in 1941 when a huge hunk of ice fell in a then much smaller lake. It created a wave that broke the natural dam and sent ice, rock and mud down upon Huaraz and the Santa River valley below. The town was buried and over 5,000 people were killed.
Today, climate change and rising global temperatures are impacting the tropical glaciers of the Andes disproportionately, similar to the way the Arctic has shouldered an uneven amount of warming in recent years. The change is bringing an array of threats to people who live in the shadow of glaciers, from degraded water quality and availability to impacts on food supplies, but GLOFs are among the most terrifying indirect effect of a warming world for those living below the mountains of ice.
A new landmark study of the effects climate change is having on the world’s rooftop – the glacier-filled Hindu Kush Himalaya mountain system – notes that the region had already seen 33 GLOFs by the year 2000.
“Accelerated glacial thinning, degraded permafrost, and additional retreat in response to rising global temperatures are expected to increase GLOF events in the future,” the report reads.
One such event damaged a hydropower station in India, affecting tens of thousands of customers, in 2016. Another in Peru’s Cordillera Blanca led to the damage of property and loss of crops in the previous decade.
Following the event in Peru, local government and international NGOs collaborated to install an early warning system to improve the response for future GLOF events. Somewhat mysteriously, however, this system was vandalized and destroyed not long after becoming operational.
Now, communities in both Asia and South America are preparing to install more early warning systems and hoping they’ll stay in place before the next flood comes, which could be at any moment.