When he is not watching his flock Silverio Chiquenayra-Quispe takes care of the Pumatalya weather station, located between the brightly coloured local council building, the chapel and the bovine artificial insemination centre. At 3,800 metres above sea level, on the high plateaus of the Andes, the little town is four hours by road from the provincial capital of Cusco in Peru.

Three times a day, at 7am, 1pm and 5pm, Chiquenayra-Quispe records the temperature, wind speed and rainfall. He takes readings for four months a year. "Every morning I send the data to the municipal radio station which broadcasts an update in Spanish and Quechua [the local language]," the shepherd says, protected by a thick anorak, his face stung by the wind. The rest of the year three other families take care of this task.

At this latitude, between the equator and the Tropic of Capricorn, climate change is not some distant threat but a very real problem with which indigenous communities, among the poorest in the world, are struggling to cope. It means less rain, more wind, increasingly large variations between the biting cold of the morning and the baking afternoon sun. Above all it has become completely unpredictable. "The weather changes very suddenly and it may rain at any time," Chiquenayra-Quispe explains, showing us the figures he marks on big sheets of white paper.

The data collected at Pumatalya since 2011 backs up eyewitness accounts by villagers who have been baffled by the weather for several years. The weather station was built as part of the first phase of the Climate Change Adaptation Programme (Pacc) launched four years ago by the Peruvian environment ministry in partnership with the Swiss Agency for Development and Co-operation (SDC). Local residents were involved in the project from the start.

"The changes impact the life of shepherds, despite them being used to extreme conditions. There is no longer enough water to keep the pasture in a decent state all year round nor to allow subsistence crops. With shorter, more violent showers, the degraded soil no longer stores the moisture," says Victor Bustinza Urviola, Pacc's deputy-co-ordinator.

The models produced by Peru's National Meteorology and Hydrology Service (Senamhi) show that these trends are going to accelerate in the coming decades. The eastern part of the Cusco region could see a 15% to 30% drop in rainfall by 2030, one of the most severe forecast for the whole country.

Bernarbe, 68, poses proudly with his dog in front of the stone dyke he built with his nephew Jorge. It is not high but sufficient to contain rainwater in a natural hollow between neighbouring hills. "Before I built this, I used to run out of water in September and it was hard-going until January. I had to sell stock," the old man says, gazing out over the reservoir where sheep and alpacas gather to drink.

To build the structure, a copy of the rain-fed qocha reservoir system used by the Incas, Bernarbe received technical assistance and some funding from the Pacc, after winning a competition on water management. "Adapting to climate change here is above all a question of combating rural poverty," says Lenkiza Angulo, the Pacc national co-ordinator. The average monthly income per household is about $100 and to meet their family's needs more and more men are being forced to migrate to big towns such as Cusco or Arequipa or to the capital, Lima.

About 100 qochas have been built, but it would take 1,000 more to meet the needs of the whole plateau, home to some 10,000 people and in recent years an even greater number of cattle, llamas and alpacas. The Brown Swiss breed of cow, which can withstand harsh weather and high altitudes, was successfully introduced in the 1970s enabling dairy cattle to replace llamas. But the amount of water the cattle require is becoming a problem and milk yields are falling.

Water is now the prime source of conflict between stock-breeders.

The Pacc chose Elio Ayaza Hullca, 33, as one of the 40 or so community "messengers" tasked with raising public awareness of how much is at stake with adaptation to climate change. He travels from village to village, equipped with a ring binder containing a dozen illustrations, which he uses to explain the problems and solutions. The residents of Pumatilla (population 250), where he lives, have voted to establish a nine-hectare conservation area to restore the pasture and plant trees again on some of the eroded slopes.

"These changes don't look that impressive, but they are beginning to show results with growing awareness in the community," says Angulo. She cites the money people are investing at their own initiative to fund projects. About $13m has been raised in all, three times more than the amount initially invested by the SDC to launch the project.

"Everyone has a part to play. We're just here to accompany them. But it does show that even under conditions of severe poverty people can be mobilised, providing projects correspond to their priorities," Angulo adds.

There are now plans to extend the experiment to other highland areas of Peru.

This article appeared in Guardian Weekly, which incorporates material from Le Monde