The Andean Glacier and Water Atlas

During drought years, glacial meltwater becomes critically important for certain areas.

Glacial meltwater can be extremely important, especially within the Tropical Andean region, which is highly populated and includes some major population centres. During a normal year, glacier meltwater contributes to around 5 per cent of the available water supply in Quito, Ecuador, 61 per cent in La Paz, Bolivia, and 67 per cent in Huaraz, Peru. During a drought year, the maximum monthly contribution of water from glaciers increases to around 15 per cent in Quito, 85 per cent in La Paz and 91 per cent in Huaraz. ‘Peak water’ has been reached for many glaciers in the Andes, meaning that meltwater runoff will continue to decrease in the future. As glaciers melt, they provide meltwater. Peak water refers to a point in time where meltwater runoff is at its maximum. For many glaciers in the Tropical Andes, ‘peak water’ was reached in the 1980s and these glaciers have been contributing less and less meltwater over time. For many glaciers, peak water has either already recently been reached or it will be within the coming 20 years. Future glacier shrinkage will lead to a long-term reduction in dry season river discharge from glacierised catchments. The highest impacts will be felt in areas where meltwater significantly contributes to the available water supply, especially during the dry season. Consequently, these are the areas with the greatest needs to adapt to a reduced availability of glacial meltwater.

Glacier retreat and volume loss is ‘locked in’ and will continue in the future across the whole of the Andes, leading to significant changes in hydrology. This will impact communities and ecosystems. The extent of loss depends on which IPCC warming scenarios are used for projections. Even under the least warming scenario, glaciers will continue to shrink. The most dramatic retreat and volume loss is expected for tropical glaciers, where even under moderate warming scenarios, volume losses of between 78 and 97 per cent are projected by the end of the century. In the Southern Andes glaciers are expected to further decrease and the rate of loss is expected to accelerate.

Climate change adaptation is essential for healthy societies and ecosystems.

The Andean region is undergoing significant climatic changes that will have far-reaching consequences for the environment, and the lives of many Andean people. Communities will need to tackle the challenges resulting from climate change, such as water scarcity, unpredictable water availability, and flooding and other climate hazards. Adaptation needs to be based on careful analysis of the underlying socio-economic factors of vulnerability to climate change in order to avoid maladaptation.

Glacial meltwater is a critical water source at certain times of the year for millions of people – most notably for those living in the Andean highlands of Bolivia, Chile and Peru.

However, its importance is seasonal and not uniform across the Andes, with people in certain regions being more reliant on it than others. The Andean highlands of Bolivia, northern Chile and southern Peru are hotspots of water stress, because of their semi- arid climate and marked seasonality. With limited hydrological storage capacity in the small upland catchment flows, glacier meltwater has so far acted as an important buffer mechanism.

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