Tropical glaciers in the Cordillera Real (Bolivia) are rapidly retreating. In the early 2000s, it was predicted that many of its small glaciers (<0.5 km2) would vanish within a few decades. More than two decades after this dire prediction, we evaluate their fate using a recently published, multitemporal inventory of glaciers in the Cordillera Real. We identify 174 glaciers that disappeared between 1998 and 2024, more than five times the number previously reported. All of the glaciers that vanished were small, as predicted, and most (79.9%) were low-lying (maximum elevation <5400 m). These losses represent 30.5% of the total number of glaciers in the Cordillera Real in 1998, but their demise accounts for only 8.5% of the total area loss between 1998 and 2024. Although a majority (62.7%) of small glaciers persist to 2024, current and projected warming will likely threaten most of those that remain.

Ice sheets leave contact with the bed at grounding lines, beyond which floating ice shelves experience no friction at their base. In places where basal friction begins to decrease upstream of the grounding line, ice sheets respond more strongly to climate forcing. However, the spatial extent of zones of low grounding line friction is poorly constrained by observations. Here, we use a steady-state model of marine-terminating ice stream flow to show that the location where basal friction begins to weaken upstream of the grounding line is accompanied by a prominent surface slope break. We then use observations of grounding zone features around the Antarctic ice sheet derived from ICESat-2 laser altimetry to find the displacement between grounding line locations determined from SAR flexure measurements and such surface slope break points. We find widespread evidence of decreasing friction hundreds to thousands of meters upstream of grounding lines around the Antarctic ice sheet, indicating that grounding lines may be more sensitive to forcing than typically assumed in ice-sheet models, where friction does not decrease upstream of the grounding line. We suggest that such an observational approach should be used to parameterize grounding line friction interpolation schemes in ice-sheet models.

We summarize and reflect on the nearly 30 studies that form this Collection on Vanishing Glaciers as a contribution to the 2025 International Year of Glaciers’ Preservation. Some of the studies in this Collection are extensions of the stories told in the Global Glacier Casualty List, a collaboration between social and physical scientists. They document glaciers in various states of demise in regions across six continents, including Svalbard, Iceland, Norway, Germany, France, Italy, Spain, Austria, Switzerland, New Zealand, Indonesia, USA, Canada, Peru, Bolivia and Chile. Vanishing glaciers affect archaeology, biodiversity, water resources, tourism, culture and glaciology itself, as we grapple with more precise definitions of dwindling ice masses and the loss of long-term monitoring sites. Landscapes are being transformed by rapid deglaciation, serving as a call to action and introducing numerous challenges for those engaged in measuring, monitoring and documenting glacier change.

Glaciers in the Tropical Andes have experienced a significant and accelerated decrease over the last few decades, primarily driven by climate change. This study aims to generate updated and temporally consistent yearly glacier outlines for the Tropical Andes of Peru and Bolivia (2016–24) by implementing a fully automatic deep learning approach. Here, the Glacier-VisionTransformer-U-Net model was extended and trained on the most recent Peruvian glacier inventory to segment debris-free and debris-covered glaciers. The model accurately reproduced the overall glacier extent, particularly in debris-free areas, though performance decreased in debris-covered sections. Between 2016 and 2024, glaciers retreated by 201.6$\pm$99 km$^2$ (14.7%) at an average rate of 1.83% a$^{-1}$, with losses concentrated at lower elevations and south- to west-facing slopes. Results suggest that glacier mapping in this region is best conducted during El Niño years, as these events minimize seasonal snow cover influence. Compared to the Randolph Glacier Inventory V7.0 (1998), 1261 glaciers have shrunk below 0.01 km$^2$, 436 of them between 2016 and 2024. Small size, low elevation and El Niño–Southern Oscillation-driven fluctuations in seasonal snow cover play an essential role in glacier persistence in the region.

This study developed a multi-process drilling system (MPDS) to extract 10 m subglacial bedrock samples beneath a 1000 m-thick region of the Antarctic ice sheet. The MPDS is made of five primary subsystems: drill rig, drill-rod module, air system, drilling fluid circulation system and generator. Each subsystem is modularly designed, allowing all components to be housed within a 20 foot container for efficient transportation across Antarctic ice sheets. The MPDS employs both compressed air and drilling fluid for ice cutting removal, utilising reverse circulation through a specially designed double-wall drill rod. A standard wireline coring drill is used to obtain subglacial bedrock samples. After fabrication and testing in China, the MPDS was sent to Antarctica in the 2024/25 season for preliminary testing. During field tests, a 110 m borehole was drilled, though no bedrock samples were retrieved. The tests identified several issues related to the drill bit, drill rig, air system, drilling fluid circulation system and the drilling fluid itself. Recommendations for future MPDS improvements have been proposed, with the expectation of obtaining subglacial bedrock cores from Antarctica within the next one to two seasons.

We located over one million icequakes that occurred during a 23 day period up-glacier of the grounding line of Rutford Ice Stream (RIS), West Antarctica. To investigate basal conditions and better understand the sliding process, we focused on sticky spots, spatially constrained clusters of regularly repeating basal icequakes. We developed a multistep workflow combining location and clustering to identify sticky spots with high confidence. The basal icequakes are consistent with low-angle slip in the ice-flow direction. Seismicity during our recording period showed weak tidal correlation and a minor sensitivity to atmospheric pressure, suggesting limited external forcing of basal processes. Icequake density was elevated on stoss sides of topographic highs likely characterized by exposed bedrock or compacted tills, and in low-lying moats eroded up-glacier of topographic highs, as well as in troughs extending down-glacier from the moats, likely reflecting hard beds that promote stick–slip. Local magnitudes followed a Gutenberg–Richter distribution with two distinct high (>2) b-values. Within sticky spots, repeating seismicity featured consistent waveforms and strong positive correlations between local magnitude and interevent time. During multihour active phases, seismic slip in sticky spots can fully accommodate ice flow, highlighting the role of stick–slip motion in basal sliding near the RIS grounding line. These results will help inform sliding relations used in numerical ice-flow models.

The piedmont lobe of San Quintín Glacier, the largest outlet of the Northern Patagonia Icefield, has recently entered a phase of rapid frontal retreat. We present results from a helicopter-borne ground-penetrating radar (GPR) survey conducted in May 2019 in the terminal zone of the glacier, combined with satellite-derived ice velocity, frontal position and surface elevation change data. GPR measurements along the flowline indicate ice thicknesses of 215–240 m in the lowermost 1400 m of the glacier. The inferred grounding line is located approximately 1500 m upstream from the 2019 calving front. Analysis of surface elevation change in 2017–19 shows mean thinning rates of -5.43$\pm$1.58 m a$^{-1}$ upstream and -1.08$\pm$1.39 m a$^{-1}$ near the terminus. Satellite-derived velocities reach up to 1050 m a$^{-1}$ in the lower glacier, with higher values observed in the later part of the observation period. Residual bed reflection power derived from the GPR profiles indicates the presence of water at the glacier bed in the terminal zone. Taken together, these observations are consistent with the development of a semi-persistent floating terminus, where basal water and buoyancy modulate surface elevation change and control frontal stability and calving style. The results provide new observational constraints on the transient behaviour of floating termini at fast-flowing outlet glaciers in lacustrine settings.