1In Europe, snow piles up on glaciers in winter and melts in summer. However, this seasonal cycle does not apply to all glaciers, including those in tropical and subtropical regions, as discovered by researchers in the early 1990s, notably as part of programmes covering high altitude glaciers in Bolivia. They measured the glacier’s mass balance, installed weather stations on and next to glacier tongues, quantified downstream water run-off and complemented their measurements with satellite images, thereby showing that tropical glaciers behave quite differently to glaciers in temperate areas: snow piles up in summer, during the wet season, and not in winter. This characteristic may give rise to unexpected behaviour when faced with climate change.

Ice coring, Chimborazo volcano, Ecuador.

2This is why, as part of the Cryobsclim project, various glaciers representative of high altitude environments of the tropical and subtropical regions were selected and monitored over a long period in Bolivia, Ecuador, and Peru as well as in the Himalayas. These observations helped track changes in the glaciers and predict their future behaviour under different climate assumptions. The objective was to grasp the possible impacts on people living downstream, whose water supply in winter, during the dry season, depends on the presence of glaciers. Researchers found that, while glaciers are stable in parts of the Himalayas, they are under considerable threat in the Andes, which will have consequences for the countries concerned.

Weather station at the summit of the Chimborazo volcano, Ecuador.

••• The Cryobsclim network helps monitor the behaviour of tropical glaciers •••

3As the only internationally recognised organisation to implement, in conjunction with Andean and Himalayan partners, the long-term monitoring of glaciers in the Global South, IRD has compiled long series of observations since the 1990s, an unrivalled data set for environments difficult to monitor. Current applications range from the quantification of glacial hazards in the Himalayas to innovative water resource management methods in Peru, Bolivia and Ecuador. In Ecuador for example, a comprehensive hydrological model has been implemented to allocate water resources in the city of Quito. It takes into account the water provided by glaciers and is used as a planning tool.

“These analytical tools have allowed us to quantify the current contribution of glaciers to water resources at regional level under extremely dry conditions. Glaciers contribute respectively 15%, 86% and up to 91% of the water for consumption of the cities of Quito, La Paz and Huaraz. This information will help managers improve the planning of actions designed to mitigate the effect of the progressive reduction in this contribution due to climate change.” 
Marcos Villacis, Quito National Polytechnic School, Ecuador