Colombia has among the highest levels of runoff offer of water in the world, providing for some 2.000 mm/year and an excess of water of 2.000 cubic km/year, or 57.000 cubic meters per capita. The Glaciers and Páramo grasslands of the Northern tropical Andes are the primary water sources for hundreds of settlements and municipal water supplies including the capital of Bogota. These fragile ecosystems are extremely vulnerable to the effects of local, regional and global climate change and are already showing signs of stress. Significant and intensifying trends in glacier retreat pose numerous threats to human development. With an average glacier linear retreat rate of 10–15 m per year, a total glacial collapse is expected in the next 100 years. According to the research, 25% of municipal headwaters show signs of water shortage, and this figure was expected to rise to 55 percent by 2015. This trend poses a great risk to the Colombian Andes where 80 percent of the national population is concentrated. Between 2015 and 2025, a highly stressed condition is projected in the water availability in Colombia, affecting water supply and ecosystem functioning in the Páramos. A reduction or in operability of renewable hydropower generation (which provides 80% of Colombia’s demand) is expected as a result of a 30% reduction in the mean flows of the Colombia Andean region basins and a maximum of 80% loss in some tributaries.
This section provides insights into projected climate change impacts on various hydrological indicators.