In a new study @NatureClimate, we model the distribution, importance, and past and future changes of #snow across all major river basins in #HighMountainAsia (HMA). @UUGeo @UtrechtUni @immerzeel 🧵[1/n]
We find that #snowmelt exceeds #glacier melt in all basins, with volumes mostly three to five times as large, even in the most glacierized basins. Climate change induced changes to HMA snowpacks may therefore have stronger impacts on the water balance glacier than retreat. [2/n]
Over the past 40 years there have been significant reductions of the snowpacks in several of HMA’s river basins, such as Syr Darya, Indus and Brahmaputra. This has resulted in shifts in timing of the snowmelt seasons and attenuations of snowmelt discharge peaks. [3/n]
If we limit temperature rise by the end of century to 1.5 °C, there will be region-wide reductions in snowmelt of only 6%. In middle-of-the-road scenario SSP2−4.5 it will reduce by 22%, but for specific basins it can be over 50%. [4/n]
Sensitivity of snowmelt changes is thus strongly dependent on the degree of climate change. So, in terms of future snow meltwater supply, there is really something to gain for people downstream from limiting future climate change. [5/n]
Differences in end of century glacier meltwater output between climate scenarios are much smaller. This is caused by specifics in timing and magnitude of increased glacial meltwater release, or “peak meltwater”, under the different scenarios (Fig. by @AntarcticGlacie) [6/n]
Nevertheless, we will lose a considerable amount of HMA glacier mass and meltwater. Percentagewise likely even more than snowmelt. But since there is much more snowmelt to begin with, snow changes will have more impact on HMA hydrology overall. [7/n]
Of course, snow and glaciers are only a part of the water availability puzzle. Climate change also affects the water supply from the mountains on many other fronts, and socioeconomic developments will strongly affect future water demands. See also: [8/n]
Want to know more about our snow study? Get the paper here nature.com/articles/s4155… or contact me @philipkraai [9/n]
Free to access read-only version of the paper is available here: rdcu.be/cm8O6
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