By Hannah Hennessy

BBC News, Huaraz



The glacial retreat at Pastoruri shows no sign of stopping

Mounds of dark rock rise up between the snow and ice, discoloured after years of being covered by the glacier.

This is Pastoruri. In the past 10 years, its ice caps have retreated by about 200m.

Soon it, like many other glaciers in Peru, will have disappeared almost completely. At about 5,000m, or just over 16,000ft, it is one of the glaciers worst affected by climate change in Peru. And Peru, in turn, is one of the countries worst affected by climate change in the world.

Sitting between the tropics, where the sun is particularly fierce, and home to more tropical glaciers than anywhere else, this South American country is especially vulnerable to rising temperatures.

Experts predict all the Peruvian glaciers below 5,500m will disappear by 2015. This is the majority of Peru's glaciers.

Marco Zapata works at the Institute for National Resources in the Andean town of Huaraz, in northern Peru. He has studied glaciers for more than 30 years and says in that time Peru has lost more than 20% of its glaciers.

One of the main reasons why Peru is so vulnerable to climate change has to do with water.

Water needs

The majority of its population lives in a narrow strip of land between the Andes mountains and the sea.

Local farmers depend on the glacial water to irrigate their crops

Pressure on water resources is only likely to grow as more and more people move to coastal cities like the capital Lima and industry expands. But the source of that water is also under pressure.

Standing at the Puerto Chuelo mountain pass above the glacier lakes at Llanganuco, Mr Zapata said:

"At the moment, we are experiencing a very strong process of glacial retreat. There is an apparent abundance of water in these mountains.

"In the rainy season there are no problems, but in the dry season the glaciers are the only ecosystem that is supporting the river.

"And this problem of the process of glacial retreat is so fast, that in a very short time, it's possible the glaciers will disappear and there will be a problem of a lack of water for future generations."

Snow caps

Emilio Himenez has farmed land in the shadow of the Llanganuco lakes for almost four decades. He irrigates his land with water from the glaciers that supply the lakes and grows a variety of fruit and vegetables which he sells at market.

Emilio Himenez and his family have farmed the land for almost 40 years

As he works in the fields with his wife and daughters, one of his grandchildren, four-year-old Frank Michael looks on.

"Perhaps in 20 more years, there won't be water if the snow caps go," Mr Himenez adds.

"It will be very sad because when there is water there is life and when there is no water, there is no life, not for the animals, or the humans, or for the agriculture. And, I don't know what situation our grandchildren will be in."