Future snowmelt from Asia’s mountain ranges may decrease drastically
Strong impacts affecting downstream communities
Glaciers are iconic benchmarks of climate change, and their meltwater represents an important water resource for people living downstream, particularly in spring and summer. A new study led by researchers from Utrecht University shows that the melting of seasonal snowpacks in Asia contributes even more to river streamflow than glacier meltwater. The water supply from snowmelt has shrunk considerably over the last 40 years and it may diminish up to 50% in the future under continued climate change, with potentially strong impacts on downstream water availability. The results were published on 24 June in Nature Climate Change.
Importance of snow in mountain ranges
The authors developed a computer model that simulates snow and compared the outcomes with their previous estimates of glacier change. “We see that for all river basins that originate in the high mountains of Asia the total amount of snowmelt is much larger than glacier melt, generally around three to five times as much,” says lead author Philip Kraaijenbrink, Assistant Professor in Quantitative Methods in Extreme Environments at Utrecht University. “Changes to the region’s snowpacks due to climate change can therefore have much stronger impacts on the water balance than retreat of its glaciers.”
Snow and glacier melt are only a part of the total water cycle.
Future of Asia’s snowpacks
The scientists predict that there will be considerable losses in the amount of snowmelt in Asia’s rivers, but the degree of future climate change plays a key role. “If we are able to limit temperature rise by the end of the century to 1.5 °C as agreed upon in the 2015 Paris agreement, we will see region-wide reductions in snowmelt of only 6%,” says co-author Walter Immerzeel, Professor in Mountain Hydrology at Utrecht University. “However, in more realistic scenarios snowmelt will be reduced by 22% and for specific regions by even more than 50%. Such reductions in meltwater input into the rivers during spring can strongly affect people downstream that depend on that water for irrigation and hydropower.”
The bigger picture
How these results will impact local water availability remains a research challenge for the future according to the researchers. “Snow and glacier melt are only a part of the total water cycle. Climate change acts on many fronts and controls the changing water supply from the mountains, but there are also socioeconomic developments to consider that affect water demands,” adds Kraaijenbrink. “Our future efforts are on quantifying all processes that impact the mountain water balance to ultimately fully understand the changing system and its impacts on society.”