The state and future of the cryosphere in Central Asia

Barandun, Martina; Fiddes, Joel; Scherler, Martin; Mathys, Tamara; Saks, Tomas; Petrakov, Dmitry; Hoelzle, Martin

doi:10.1016/j.wasec.2020.100072

Cited by 32 publications

(24 citation statements)

References 148 publications

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“…The annual excess meltwater contribution increases to ≈16% and ≈7% for most negative mass balance years (Figures 4a and 4b). Despite a relatively low annual contribution, melt water excess can become crucial during dry summer months (Armstrong et al., 2019; Barandun et al., 2020; Pritchard, 2019). Glacier melt from June to September can increase by ≈90% (Naryn) and ≈40% (Gunt) above average monthly melt production during an extreme negative mass balance year (Naryn: 2001/02; Gunt: 2007/08, Figure 4c).…”

Section: Relevance Of Glacier Mass Loss To River Runoffmentioning

confidence: 99%

“…The synthesis of regional mass balance dynamics on annual to seasonal time scales for Tien Shan and Pamir is challenging because glaciological data sets are sparse (Barandun et al., 2020; Hoelzle et al., 2019; Unger‐Shayesteh et al., 2013). Therefore, most hydrological models for glacier melt quantification are calibrated on auxiliary data sets rather than actual measurements, hampering their reliability (Pritchard, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Hot Spots of Glacier Mass Balance Variability in Central Asia

Barandun

Pohl

Naegeli

et al. 2021

Geophysical Research Letters

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The Tien Shan and Pamir mountains host over 28,000 glaciers providing essential water resources for increasing water demand in Central Asia. A disequilibrium between glaciers and climate affects meltwater release to Central Asian rivers, challenging the region's water availability. Previous research has neglected temporal variability. We present glacier mass balance estimates based on transient snowline and geodetic surveys with unprecedented spatiotemporal resolution from 1999/00 to 2017/18. Our results reveal spatiotemporal heterogeneity characterized by two mass balance clusters: (a) positive, low variability, and (b) negative, high variability. This translates into variable glacial meltwater release (≈1-16%) of annual river runoff for two watersheds. Our study reveals more complex climate forcingrunoff responses and importance of glacial meltwater variability for the region than suggested previously.Plain Language Summary Glaciers in Central Asia act as water towers for millions of people by storing and releasing water in response to climate. Monitoring glaciers is difficult due to their often very remote locations. Satellite remote sensing has emerged as a powerful method but a drawback is their (semi-)decadal resolution for glacier mass change surveys. We present a methodology, combining multiyear elevation change maps with frequent snowline observations to estimate mass changes and variability at annual scale, which allows us identifying so far unrecognized regions of contrasting trends for the Tien Shan and Pamir mountains. These "hot spots" reveal a far more complex climate-glacier interplay than previously known. The additional meltwater released from the retreating glaciers varies considerably and contributes to the river flow for warm dry years by twice as much as for cold wet years. Our findings will help to better understand the impact of climate change on Central Asian glaciers and their meltwater release. BARANDUN ET AL.

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Section: Relevance Of Glacier Mass Loss To River Runoffmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hot Spots of Glacier Mass Balance Variability in Central Asia

Barandun

Pohl

Naegeli

et al. 2021

Geophysical Research Letters

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“…Glacial runoff has a seasonal signature distinct from that of precipitation-driven runoff, generally peaking later in the warm season when rains have already subsided (Hagg et al, 2013;Huss and Hock, 2018;Barandun et al, 2020). As a result, in basins where glacial runoff is a substantial fraction of total runoff, accounting for glacial runoff can shift the moisture balance from month to month.…”

Section: B42 Effect Of Shift In Seasonalitymentioning

confidence: 99%

Glacial runoff buffers droughts through the 21st century

2022

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Abstract. Global climate model projections suggest that 21st century climate change will bring significant drying in the terrestrial midlatitudes. Recent glacier modeling suggests that runoff from glaciers will continue to provide substantial freshwater in many drainage basins, though the supply will generally diminish throughout the century. In the absence of dynamic glacier ice within global climate models (GCMs), a comprehensive picture of future hydrological drought conditions in glaciated regions has been elusive. Here, we leverage the results of existing GCM simulations and a global glacier model to evaluate glacial buffering of droughts in the Standardized Precipitation-Evapotranspiration Index (SPEI). We compute one baseline version of the SPEI and one version modified to account for glacial runoff changing over time, and we compare the two for each of 56 large-scale glaciated basins worldwide. We find that accounting for glacial runoff tends to increase the multi-model ensemble mean SPEI and reduce drought frequency and severity, even in basins with relatively little (<2 %) glacier cover. When glacial runoff is included in the SPEI, the number of droughts is reduced in 40 of 56 basins and the average drought severity is reduced in 53 of 56 basins, with similar counts in each time period we study. Glacial drought buffering persists even as glacial runoff is projected to decline through the 21st century. Results are similar under representative concentration pathway (RCP) 4.5 and 8.5 emissions scenarios, though results for the higher-emissions RCP 8.5 scenario show wider multi-model spread (uncertainty) and greater incidence of decreasing buffering later in the century. A k-means clustering analysis shows that glacial drought buffering is strongest in moderately glaciated, arid basins.

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“…Glacier mass balance evolution in Central Asia is a key variable to determining the impact of climate change on water availability [1][2][3][4][5]. Glaciers store water and act as water towers; this water can be used for irrigation and hydropower [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Reconstructed Centennial Mass Balance Change for Golubin Glacier, Northern Tien Shan

et al. 2022

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Mass balance measurements for Golubin glacier in Northern Tien Shan, Kyrgyzstan, have been discontinuous over the last century, with significant data gaps. We provide a unique over 100-year-long mass balance series on daily resolution. We applied a temperature index model calibrated with glaciological measurements and validated with secular mass balances derived from independent length change observations. A comparison with other recent geodetic studies reveals good agreement. Golubin lost −0.16 ± 0.45 m w.e. a−1 from 1900/1901 to 2020/2021. From the long-term mass balance time series, we identify a shift to a more negative/less positive regime with time, with a steepening of the ablation and accumulation gradients, especially for the past two decades. We observe a parallel shift of the mass balance gradient accompanied by a rotation of the ablation gradient due to increased ablation at the glacier tongue and accumulation above the equilibrium line altitude. This tendency is believed to intensify in the future, affecting glaciers’ mass balance sensitivity to changes in atmospheric conditions and year-to-year variability and resulting in irregular melt water release feeding the rivers that provide water to Bishkek. These kinds of datasets are sparse for Tien Shan and, yet, indispensable to enhancing our understanding of glacier changes in High Mountain Asia.

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The state and future of the cryosphere in Central Asia

Cited by 32 publications

References 148 publications

Hot Spots of Glacier Mass Balance Variability in Central Asia

Hot Spots of Glacier Mass Balance Variability in Central Asia

Glacial runoff buffers droughts through the 21st century

Reconstructed Centennial Mass Balance Change for Golubin Glacier, Northern Tien Shan

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