12 March 2007James Painter
Government officials, water experts and environmentalists agree the rapid melting of the spectacular Andean glaciers featured in the film is threatening the long-term economic and human development of what is South America's most "water-stressed" country.
 |  The Cordillera Blanca provides drinking water and electricity |
"Global warming for us is not just about the environment," warns Julio Garcia of Peru's National Council on the Environment, Conam.
"It's more about how on earth we can develop Peru in a sustainable way over the coming years."
Peru's water problem lies in part in the peculiar geography of the country.
Most of the Pacific coast would be desert if it were not for the water flowing down from the Andes.
Seventy per cent of the population live along the coast, where less than 2% of the country's water resources are found.
In contrast, the Atlantic side of the Andes has 98% of the water and about a quarter of the population.
"Much of our water supply is on the wrong side of the wall," says Mr Garcia.
Glacial melt
Peru has the largest number of tropical glaciers in the world. These water towers are crucial for slowly releasing water, particularly in the dry season. And Peru desperately needs the water all year round.
Apart from the need for drinking water, 80% of the country's power has traditionally come from hydro-electricity. And, the current boom sectors of the economy - agro-exports and mining - also absorb huge volumes of water.
The latest figures on glacial melt are alarming.
Estimates by a team of Peruvian and international scientists say that Peru and Bolivia, which together account for more than 90% of the world's tropical glaciers, have lost about a third of the surface area of their glaciers between the 1970s and 2006.
A lot of attention has been paid to the range known as Cordillera Blanca, home to Peru's largest mountain, Huascaran, at 6,768 metres (22,200ft).
Water coming down from the range feeds an array of economic activities in the Rio Santa valley below it.
This includes a hydro-electric plant providing 5% of Peru's electricity, drinking water for two cities, and commercial and small-scale agriculture.
"Water from glaciers is absolutely critical for the valley in the six or seven months of the dry season," says Gabriela Rosas, a researcher at the national weather institute, Senamhi.
Glacial melt is calculated to provide 10 to 20% of the total annual water run-off in the valley, but it can reach 40% in the dry season.
Ms Rosas is part of a team modelling future water availability in Peru.
The models, based on moderate rises in temperature, predict annual water availability will increase slightly as more of the glaciers melt, but that there will be a dramatic decline after 2050 and possibly as early as 2030.
Seasonal variations will become more intense, with less water available in the dry season.
Low reserves
Lima, Peru's capital, is a particular worry.
 The government wants more people to have water connections (Photo: Peru Support Group) |
The city gets most of its water from the Rio Rimac and two other rivers with sources high up in the Andes. The rivers are partly fed by glacial melt, although less than the Rio Santa valley.
"Lima already has a large deficit between supply and demand and official projections say it's going to get a lot larger in the future," says Juan Carlos Barandiaran, former head of projects for the municipal water company, Sedapal.
Demand is set to increase as the city absorbs thousands of new arrivals every year.
"We must have more reserves," says Mr Barandiaran.
The last major drought in 2004 pushed the city's water supplies to the limit. "If we had droughts two years running our current reserves would not support it," he says.
President Alan Garcia's government wants to give water connections to nearly a million more people in Lima, but experts say this will increase demand even more.
The project is known as "Agua para todos" or "Water for all". But, says Sedapal's former president, Carlos Silvestri: "It will be very little water for all."
'Vulnerable'
For several years, Mr Silvestri and other experts have been urging successive governments to build a range of multi-million-dollar infrastructure works, including a second tunnel through the Andes, in order to build up their reserves.
Such works have become even more urgent with the prospect of reduced water in the dry season. They could capture and store more water during the wet season.
"We are only city in South America with so few reserves - less than a year's supply. We are very vulnerable," says Mr Silvestri.
He also worries about the increased frequency and intensity of droughts due to El Nino, and Lima's current reliance on just one 60-km (37-mile) tunnel fetching water from the other side of the Andes. And now there's glacial melt.
"We really are on the edge of an abyss," he warns.
Scientists say it is hard to predict in how many years the effect of glacial melt will really bite. But it is remarkable how many experts in Peru take seriously the prediction that the time will come this century when a barrel of water will cost more than a barrel of oil.
