Observed and projected declines in glacier albedo across the Third Pole in the 21st century

• Published in: One earth (Cambridge, Mass.) Vol. 7; no. 9; pp. 1587 - 1599
• Main Authors: Ren, Shaoting, Jia, Li, Miles, Evan S., Menenti, Massimo, Kneib, Marin, Shaw, Thomas E., Buri, Pascal, McCarthy, Michael J., Yang, Wei, Pellicciotti, Francesca, Yao, Tandong
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 20.09.2024
• Subjects: climate change; glacier albedo; glacier darkening; MODIS; remote sensing; Third Pole; Tibetan Plateau; Tibetan Plateau; glacier darkening; Third Pole; remote sensing; glacier albedo; MODIS; climate change
• ISSN: 2590-3322; 2590-3322
• DOI: 10.1016/j.oneear.2024.08.010

Glaciers are crucial water resources in the Third Pole (the Tibetan Plateau and its surroundings) and are shrinking in response to climate change. Glacier albedo is an expression of glacier interactions with climate and dust/black carbon, and albedo reduction enhances glacier mass loss, but its changes and potential drivers remain poorly quantified. We leverage satellite observations to explore the variability of glacier albedo and understand its sensitivity to potential drivers and its future evolution. We find that glacier albedo has declined during 2001–2020, but high interannual variability is also an important signal. These variations are highly sensitive to air temperature and snow conditions and to nearby dust/black carbon emission sources. Future changes to these drivers will lead to further decreases of 2.9%–12.5% in glacier albedo by 2100 under different warming scenarios. These findings highlight the importance of albedo in glacier future evolution and the urgency of action to mitigate climate warming. [Display omitted] •Glacier albedo is highly variable across distinct subregions of the Third Pole•Interannual variability belies long-term decreases in glacier albedo•Air temperature and snow are primary drivers of changes in glacier albedo•Third Pole glaciers will continue to darken during the 21st century Glaciers in the Third Pole (i.e., the Tibetan Plateau and its surroundings) supply more than a billion people with freshwater resources for societal, environmental, and economic needs, but they are shrinking. Glacier albedo, which measures how much solar radiation is reflected by a glacier, is a physical link between glacier changes and variations in climate and atmospheric particles. As glaciers darken, they absorb more energy, which has been identified as a key driver of glacier shrinkage in this region, possibly shaping future glacier trajectories. However, glacier albedo changes in the 21st century remain poorly understood. Using satellite observations, we find that glacier albedo has declined over 2001–2020 in most regions of the Third Pole, and the moderate and high warming scenarios imply strong further decreases by 2100, contributing to the continuing demise of Asian glaciers. These findings underline the importance of albedo in glacier projection and the urgency of mitigating climate warming. Glacier albedo is a key control of glacier mass loss in the Third Pole, but its changes and potential drivers are still poorly quantified. Leveraging satellite-derived glacier albedo and newly developed albedo estimation models, this study reveals continuous glacier darkening in the 21st century and the associated mass loss. These findings highlight the key role of glacier albedo in enhancing future glacier ablation and the urgency of mitigating climate warming and atmospheric light-absorbing particles for the persistence of Asian glaciers.