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The glaciers in the tropical Andes shrunk between 30 and 50% in 30 years, which represents the highest rate observed over the last three centuries. IRD researchers and their partners( 1) recently published a summary which chronicles the history of these glaciers since their maximum extension, reached between 1650 and 1730 of our era, in the middle of the Little Ice Age*. The faster melting is due to the rapid climate change which has occurred in the tropics since the 1950s, and in particular since the end of the 1970s, leading to an average temperature rise of 0.7°C in this part of the Andes. At the current pace of their retreat, small glaciers could disappear within the next 10 to 15 years, affecting water supply for the populations.
Thawing is taking place the world over as a result of global warming, and the diversity of mountain ecosystems is thus under threat. IRD researchers and their partners( 1), writing in the journal Nature Climate Change , have just revealed that the retreating glaciers may lead to the extinction of between 10 to 40% of aquatic fauna depending on the region - tropical, temperate or arctic. Ecologists have been studying the biodiversity of streams created by meltwater in the the páramos, a typical landscape feature in the Andes) situated at an altitude of between 3,500 and 5,000m. The species that make these streams their home, mostly insects, are endemic to these extreme environments and subjected to a combination of ice and intense sunlight, aggressive winds, etc. The disappearance of such exceptional fauna would lead to a loss in the conservation of such ecosystems, which are unique in the world. However invertebrates also have a role to play as bio-indicators, particularly regarding the quality of the water that supplies downstream towns and cities such as Quito, the capital of Ecuador.
More than three quarters of the land in Mexico is suffering from erosion. Desertification is accentuated partly by the aggressive climate and rugged topography but mostly by human activity. The phenomenon has led to much activity since 1995: politicians, authorities and local communities have been working together to create sustainable management of the natural resources in water, forests and soil.
The drainage basin of Morelia, the capital of Michoacán, is emblematic of the situation. A Franco-Mexican team of researchers from the IRD, UNAM, UMSNH and ColPos( 1) have selected the region as a pilot study as part of the REVOLSO, STREAMS and DESIRE( 2) programmes, to define the runoffs and develop suitable strategies. Actions have included hydrological monitoring, agronomic essays and socio-economic studies, with participation from local communities, political bodies and the authorities( 3). Cultivation of alternative crops such as agave – used in the production of mezcal( 4) – has been initiated, enabling a reduction in harm to the environment and also a improvement in revenue and quality of life for local inhabitants.
The Red River is the second largest river in Vietnam after the Mekong, providing a livelihood for nearly one third of the country’s population, including the inhabitants of the capital Hanoi. A centuries-old river management system is in place, which controls both the river’s violent floods and water availability.
Over the last 10 years, with the backing of international institutions and donors, the Vietnamese government has established a new water governance structure. Three River Basin Organizations, including the Red River Basin Organization, were superimposed over pre-existing authorities, leading to a greater complexity of water management. The IRD and International Water Management Institute scientists studying the water sector reorganization in Vietnam have shown the lack of effectiveness of this reform. The reorganization, disconnected from established structures, has proved to be disappointing: pricing water resources did not produce the expected benefits, integrated river basin management is proving to be difficult to implement, conflicts have emerged between various authorities… In the long term, this confusion may have a positive effect by triggering some changes, and this study demonstrates that reforms in the water sector must take into account existing management structures.
Lake Chad used to be one of the biggest lakes in the world, but its volume has been reduced to a tenth of what it was in the 1960s. The way this lake has dried up has become a symbol of climate change in action. It’s true that the lake’s water level has always changed, but this hasn’t diminished the major changes to the lifestyle of the inhabitants of the lake’s shoreline. Yet, as demonstrated by a French-Nigerian team including the IRD( 1), lake dwellers have made the best of these changes to their environment. Formerly fishermen or herdsmen, they have become farmers, often growing for export. The land that was part of the lake has made it possible for them to develop highly productive crops such as corn, rice and cowpea. In the valley of the Komadugu Yobe River in Niger, they have even commenced the intensive farming of peppers, which is highly lucrative although risky.
Rewatering the lake, as proposed by the Ubangi( 5) international project, would cause upheaval once again to the farming system, particularly if the yearly rise and fall in lake water levels were to cease.