Peru's retreating glaciers stir water-supply worries

PASTORURI GLACIER, Peru — Peru's "White Mountain Range" may soon have to change its name.

The ice atop Cordillera Blanca, the largest glacier chain in the tropics, is melting fast because of rising temperatures, and peaks are turning brown. The trend is highlighting fears of global warming and, scientists say, is endangering future water supplies to the arid coast where most Peruvians live.

Glaciologists consider the health of the world's glaciers an indicator of global warming, and they warn that what is happening in the Andes signals trouble ahead.

"To me it's the rate of ice loss that's a real concern" because when melting accelerates, the ice cannot replenish itself, said Lonnie Thompson, a leading glacier expert at Ohio State University.

Thompson, a geologist monitoring glacier retreat on the Andes, Himalayas and Kilimanjaro, said tropical glaciers are melting all over the world because of rising temperatures, "and where we have the data to prove it, the rate of ice loss is actually accelerating."

In southern Peru, Quelccaya, the world's largest tropical ice cap, is retreating about 200 feet a year, up from 20 feet a year in the 1960s, Thompson said. Melting is also visible in the other Andean nations — Colombia, Venezuela, Ecuador and Bolivia.

In Peru, home to 70 percent of Earth's tropical glaciers, the Andes mountains have lost at least 22 percent of their glacier area since 1970 and the melt is speeding up, according to Peru's National Resources Institute, INRENA, a government agency.

Rock shows through lavishly snow-covered mountains throughout the Peruvian Andes. The Broggi glacier has disappeared altogether. Ice caves once popular with tourists are gone.

On Cordillera Blanca, which has 35 percent of Peru's glaciers, Marco Zapata, head of INRENA's glaciology unit, trudges up a barren, rocky mountain slope that until recently was covered by a centuries-old layer of ice. He points to a small, white mound on the retreating Pastoruri glacier, 17,000 feet above sea level.

A month earlier, that mound was an ice cave — Pastoruri's last — until the cavern's crystalline arch collapsed under an unseasonably warm sun. The remnants are melting into a newly formed lagoon.

Glaciers feed rivers crucial to the sprawling cities and shantytowns on Peru's bone-dry Pacific coast. They also serve agriculture and hydroelectric plants that generate 70 percent of Peru's power.

Two-thirds of Peru's 27 million people live on the coast, where just 1.8 percent of the nation's water supply is found. Shantytowns spring up virtually overnight in sandy dunes around the capital, Lima, and providing them with water is costly, says Julio Garcia of the National Environment Council, CONAM.

President Alan Garcia believes the rush of melted water could mean abundant hydropower for Peru and its neighbors. Garcia agrees it's feasible but doubts the water bonanza will last beyond 2050.