Almost 2 billion people could be negatively affected by the decline of natural “water towers” (glaciers and snow that store water in winter and release it gradually in warmer seasons) due to rising temperatures, according to a new report. Asian river basis face the greatest demands but there is increasing vulnerability in Europe and North America.
The overexploitation of freshwater resources threatens food security and the overall wellbeing of humankind in many parts of the world. The maximum global potential for consumptive freshwater use is approaching rapidly, regardless of the estimate used. Due to increasing population pressure, changing water consumption behaviour, and climate change, the challenge of keeping water consumption at sustainable levels is projected to become even more difficult in the near future.
It is predicted that there will be accelerating glacier mass loss and disruption in snow-melt as temperatures are rising faster at higher altitude than the global average overall.
This new assessment, published in Nature magazine 9 December, is the first to examine high-altitude water sources. The Indus, which flows downstream to densely populated basins in India, Pakistan, Afghanistan and China, is the most important and the most vulnerable of the systems studied.
In particular, the scientists predict that the Indus system will be unlikely to support environmental, agricultural and human demand by 2050. This conclusion is based on an estimated increase in population of 50 percent coupled with a 1.9 C degree rise in temperatures and a limited 2 percent increase in rainfall.
The report examined precipitation and ice and water storage in glaciers, snow cover, lakes and rivers in 78 mountain ranges. This information was compared to utilization by populations, industries and agriculture downstream.
“It’s not just happening far away in the Himalayas but in Europe and the United States, places not usually thought to be reliant on mountains for people or the economy,” said one of the authors, Bethan Davies, of Royal Holloway University, London, UK.
“We always knew the Indus was important, but it was surprising how the Rhône and Rhine have risen in importance, along with the Fraser and Columbia.”
The report concludes with a call for immediate action on both the local and international level. The scientists cite research by the UN Intergovernmental Panel on Climate Change: 75 percent of high-altitude snow and ice could be retained if global warming could be kept within 1.5C. However, 80 percent would be lost by 2100 if the world continued on a path of business as usual.