For Andean countries, the ice-capped glaciers that tower above countless communities in the highlands are the water supply regulators and a sort of natural storage tank for the resource. Glaciers not only feed rivers and other bodies of water in the dry season, as their presence also affects weather. But as temperatures rise, they are melting rapidly, threatening water supplies that are tied to glaciers´ precarious state.
Climate change has been noted to change even the water cycle itself, altering the quantities, speeds and distribution of precipitation.
Temperatures have risen so quickly that the human population has been unable to adapt to the subsequent rapid glacier melt.
“Studies show some trends, but we don´t know when there will be intense rain or when we´ll have a drought. The indicators or trends in the Andean world don´t work anymore,” said Pedro Ferradas, who heads a disaster prevention program at the international development organization Practical Action-ITDG that provides technical assistance for low-income communities.
The melting Andean glaciers are one of the most dramatic examples of global warming´s impact.
Peru has been the most affected. The country is home to 70 percent of the world´s tropical glaciers, and is already particularly vulnerable to water shortages because some 70 percent of its population of 29 million people lives on the desert coast, home to 1.8 percent of the country´s water supply. Some 98 percent is found on the other side of the Andes mountains in the Amazon basin.
But over the past three decades, 30 percent of Peru´s glaciers have melted, an amount of water that could supply the capital Lima, a city of more than 8 million people, for a decade.
Quickly retreating glaciers have also affected Bolivia, which holds 22 percent of the world´s tropical glaciers; Ecuador, home to 4 percent, and Colombia, with 3 percent, according to the Andean Community of Nations. Glacier water supplies major cities in these Andean countries.
Only 3 percent of the earth´s water is fresh water, and close to 80 percent comes from glaciers, while a fifth is subterranean and 1 percent is surface water.
Bolivia´s iconic Chacaltaya glacier, at 5,300 meters above sea level, has disappeared, six years earlier than it was estimated to have completely melted.
Ecuador´s Cotopaxi and Antisana glaciers have lost between one third and half of their ice cover, spelling bad news for the capital Quito, whose water consumption comes from those glaciers. Eight of Colombia´s 15 glaciers are expected to completely melt in the next 50 years, and the other seven are averaging 20 meter-retreats per year over the last decade.
In the dry season or when rainfall is low, glaciers “are a fundamental source of water for the rivers that feed cities and serve as the raw material for hydroelectric plants,” said Jorge Recharte, director of the Andean program at the Mountain Institute, a Washington-based organization that aims to preserve mountain environments around the world, including the Andes.
Of Peru´s 3,044 glaciers, 1,129 are on the Pacific Ocean side of the Andes and supply the bone-dry coast with water.
“The support of that glacier water will depend on the flow and length of the rivers,” said Llerena. “That´s why it´s important to research how much each glacier supports each river.”
Water and mining
The health of the páramos, lush, high elevation (above 3,500 meters above sea level) glacier-formed and glacier-fed valleys, a sort of natural infrastructure, impacts lower-altitude zones.
But some of these areas are being threatened by mining, a highly-toxic industry that requires enormous amounts of water.
“How can you have both water and mineral exploitation?” asked Llerena. “There are circumstances in which you have to choose one resource.”
Both large-scale mining and informal or small-scale mining pose major threats to rivers for contamination, which puts local farming at risk as well.
But adaptation may be the only way out. Ferradas says policymakers should take local community knowledge about water storage into account, such as the construction of artificial lagoons.
Land use for heavy industry that calls deforestation is another problem with impacts on biodiversity and climate itself. “These are parallel processes that affect one another,” said Llerena.