In a commentary published in Nature News & Comment, an international group of climate researchers highlight the threat that collapsing glaciers are posing on Asia’s water supplies (1). In particular, Gao and colleagues point out the extent to which tracking moisture, snow, and meltwater across the ‘third plateau’ could help communities to prepare for and better adapt to climate change.
The so-called third pole, which includes the Himalayan mountains and Tibetan Plateau, accounts for the largest area of snow and ice after the Arctic and Antarctica. The region supplies nearly 20 per cent of freshwater sourced from the run-off of ten rivers, including the Indus, Brahmaputra, Ganges, Yellow, and the Yangtze. However, just like the polar ice caps, the Himalayas and Tibetan Plateau have been shrinking for the last 50 years.
The main sources of precipitation are the monsoons and westerly winds, as well as evaporation and transpiration from soils and plants. However, the highly complex mountainous terrain can lead to huge variations in weather patterns and climate change. Yet scientists still do not fully understand why some rivers are at risk of drying up due to unusually arid conditions, whereas other regions are at risk of flooding as rivers, such as the such as the upper Ganges and Mekong basins, continue to swell caused by increased precipitation and accelerated melting (2).
According to the authors, “Communities need information to help them manage risks and water supplies.” They also highlight the importance of knowing “which glaciers are melting fastest, and how changing snowfall and a warmer climate are affecting the accumulation and disappearance of ice and the volumes of rivers and lakes.” But current climate models and satellite images are not accurate enough to identify changes on a local level, particularly owing to the high altitude of the region. To remedy this, a network of monitoring stations is being set up to track water movements.
An international scientific programme called the Third Pole Environment aims “to study environmental change processes and mechanisms on the third pole and their influences and regional responses to global change.” So far, as part of the effort, researchers from the Institute of Tibetan Plateau Research and the Chinese Academy of Sciences in Beijing have set up eleven monitoring stations in the region since 2014.
The ground stations will track meteorological variables, such as air temperature, humidity, air pressure, precipitation and winds, in addition to water cycle data based on measurement of the stable isotopes of hydrogen and oxygen found in water vapour. The information will help researchers understand where atmospheric moisture comes from and hopefully provide insights into the complex weather patterns of the third pole’s difficult yet beautiful terrain. The new data could also help tailor computer models.
One day, the authors hope to better understand the processes involved in the two main weather patterns responsible for diving most of the moisture flow across the third pole, the Indian monsoon and prevailing westerly winds.
(1) Gao, J. et al. Collapsing glaciers threaten Asia’s water supplies. Nature (2018). DOI: 10.1038/d41586-018-07838-4
(2) Lutz, A.F. et al. Consistent increase in High Asia’s runoff due to increasing glacier melt and precipitation. Nature Climate Change (2014).