Our campaigners are kicking up a storm at the UN climate change talks in Poland right now. And I imagine one message they want to get across is that climate change is about people. Especially, people living in poor countries - those who have done the least to cause climate change, but are being hit the hardest.

People like Olga Morales, a potato farmer in the Peruvian Andes. She lives in the shadow of Huascarán, the highest peak in the country, and relies on glacial melt water to grow her potatoes. Trouble is, that water is disappearing.

"There is less and less water now," she tells me. "Before, when we would irrigate the land, it would last two weeks, now it only lasts four days because the sun is so strong. Water used to come from Huascarán, but now it's coming less and less. The snow on Huascarán is only up, up, up above, and each day it goes further up. Huascarán is dying because of the heat."

Peru is being hit hard by climate change. It's widely regarded as the most water-stressed country in Latin America. The majority of the population is almost entirely dependent on water from the Andean glaciers for farming, homes, and electricity.

But that water is drying up - 22 per cent of Peru's glaciers has disappeared in 35 years. And it's predicted that most of the glaciers will vanish completely in 15 years - because of climate change. This will have catastrophic consequences for all Peruvians, and especially those dependent on melt water for their crops and homes.

Olga's uncle Leoncio has lived beneath Peru's glaciers for 77 years, and has seen many changes. "The climate is warmer now," he says. "I can tell by how the plants grow differently and dry out. And I can tell because of Huascarán. The snow used to come to this level, but no more. Everyone says there won't be any water left from the mountain."

But Olga and Leoncio are fighting back. They've recognised their water is disappearing, and are doing all they can to store it and use it as sparingly as possible. That means small steps like drip irrigation (hoses and pipes with tiny water holes), and larger steps like building community reservoirs.

But their fight won't mean anything if we don't support them, and tell our leaders that we have to cut carbon emissions before it's too late. As Olga warns: "It's going to get worse. It's going to get hotter. Huascarán will continue to melt and die, and we won't have any water."

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