Hot spots of glacier mass balance variability in Central Asia

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 forcing-runoff responses and importance of glacial meltwater variability for the region than suggested previously.ISSN:0094-8276ISSN:1944-800

Distributed global debris thickness estimates reveal debris significantly impacts glacier mass balance

International audienc

The ice-free topography of Svalbard

We present a first version of the Svalbard ice-free topography (SVIFT1.0) using a mass-conserving approach for mapping glacier ice thickness. SVIFT1.0 is informed by more than 900’000 point-measurements of glacier thickness, totalling almost 8’300 km of thickness profiles. It is publicly available for download. Our estimate for the total ice volume is 6’253km3, equivalent to 1.6cm sea-level rise. The thickness map suggests that 13% of the glacierised area is grounded below sea-level. Thickness values are provided together with a map of error estimates that comprise uncertainties in the thickness surveys as well as in other input variables. Aggregated error estimates are used to define a likely ice-volume range of 5’200-7’400km3. The ice-front thickness of marine-terminating glaciers is a key quantity for ice-loss attribution because it controls the potential ice discharge by iceberg calving into the ocean. We find a mean ice-front thickness of 133m for the archipelago

Snow Moving to Higher Elevations : Analyzing Three Decades of Snowline Dynamics in the Alps

In the Alps, snow cover dynamics can be monitored using Earth observation (EO). However, low revisit frequency and cloud cover pose a challenge to long‐term time series analysis using high spatial resolution EO images. In this study, we applied the random forest regression to model regional snowline elevations (RSEs). In this manner, daily snowline dynamics and their long‐term trends can be derived, despite the aforementioned challenges. Of the six investigated Alpine catchments between 1984 and 2018, a significant increasing trend of RSEs is shown in four catchments in the early ablation seasons (between 5.38 ± 2.64 and 11.29 ± 4.79 m·a−1) and five catchments in the middle ablation seasons (between 4.17 ± 2.62 and 8.76 ± 4.42 m·a−1). On average, the random forest regression models can explain 75% of the RSE variations. Furthermore, air temperature was found influential in snow persistence especially during middle and late ablation seasons