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Rockwall erosion in high-alpine glacial environments varies both temporally and spatially. Where rockwalls flank glaciers, changes in debris supply and supraglacial cover will modify ice ablation. Yet, quantifying spatiotemporal patterns in erosion across deglaciating rockwalls is not trivial. At five nearby valley glaciers around Pigne d'Arolla in Switzerland, we derived apparent rockwall erosion rates using .sup.10 Be cosmogenic nuclide concentrations ([.sup.10 Be]) in medial moraine debris. Systematic downglacier sampling of six medial moraines that receive debris from rockwalls with differing orientation, slope, and deglaciation histories enabled us to assess rockwall erosion through time and to investigate how distinct spatial source rockwall morphology may express itself in medial moraine [.sup.10 Be] records. Our dataset combines 24 new samples from medial moraines of Glacier du Brenay, Glacier de Cheilon, Glacier de Pièce, and Glacier de Tsijiore Nouve with 15 published samples from Glacier d'Otemma. For each sample, we simulated the glacial debris transport using a simple debris particle trajectory model to approximate the time of debris erosion and to correct the measured [.sup.10 Be] for post-depositional .sup.10 Be accumulation. Our derived apparent rockwall erosion rates range between â¼ 0.6 and 10.0 mm yr.sup.-1 . Whereas the longest downglacier [.sup.10 Be] record presumably reaches back to the end of the Little Ice Age and suggests a systematic increase in rockwall erosion rates over the last â¼ 200 years, the shorter records only cover the last â¼ 100 years from the recent deglaciation period and indicate temporally more stable erosion rates. For the estimated time of debris erosion, ice cover changes across most source rockwalls were small, suggesting that our records are largely unaffected by the contribution of recently deglaciated bedrock of possibly different [.sup.10 Be], but admixture of subglacially derived debris cannot be excluded at every site. Comparing our sites suggests that apparent rockwall erosion rates are higher where rockwalls are steep and north-facing, indicating a potential slope and temperature control on rockwall erosion around Pigne d'Arolla.

We present new chronological and palaeoclimatological constraints on the evolution of the Valsugana glacier network (south-eastern European Alps) during the Last Glacial Maximum (LGM). The detection of ice-marginal sediments and landforms, related to the geological mapping of the area at 1 : 50 000 scale (CARG project, sheet 061 \"Borgo Valsugana\"), enabled a detailed reconstruction of past glaciers at their maximum extent. Chronological control on the geomorphological evidence is obtained using .sup.10 Be surface exposure dating of erratic boulders from lateral moraine ridges at Monte Lefre, a nunatak within the LGM ice network. The exposure ages cluster between 20 and 19 ka, demonstrating that lateral moraines were formed at the very end of the LGM and that ice surface lowering in the area did not start prior to ca. 19 ka. Isolated from the Valsugana glacier network, several smaller ice masses developed. The reconstruction of four of these isolated glaciers and their equilibrium line altitudes (ELAs) allows us to better understand the climatic conditions that controlled glacier evolution during the LGM: glacier ELAs were lowest in the Venetian Prealps (ca. 1300-1500 m a.s.l.) and were gradually rising towards the more internal mountain chains (ca. 1500-1700 m a.s.l.). This ELA gradient suggests that precipitation sourced from the Mediterranean Sea was highest in the vicinity of the Alpine fringe, with successive moisture starvation towards the north. The detailed glacier reconstructions, the chronological data, and the palaeoclimatological insights may serve as ground control for future modelling efforts of large and interconnected palaeoglacier networks.

Ongoing speculation regarding the existence of large Late Pleistocene ice masses in Northeast Eurasia reflects the dearth of age constraints on glaciations across this vast region. Here, we report the first dates from the central part of Northeast Siberia, consisting of 22 cosmogenic 10Be exposure ages from boulders deriving from a sequence of three moraines in the Chersky Range. The dated moraine sequence indicates progressive contraction of maximum glacier extent from Marine Isotope Stage 6 to the Last Glacial Maximum, while the remotely‐sensed mapping indicates an older, more expansive glaciation in the region yet undated. Our results show that Late Pleistocene glaciations were limited to the highlands, and Northeast Siberia did not host a large, coalescent ice sheet during the Last Glacial Maximum or Marine Isotope Stage 6. Plain Language Summary Very little is known about the glacial history of Northeast Siberia, which has led to speculations concerning the size and timing of past ice masses in this vast region. Some have previously suggested the area was covered by a large ice sheet during the Last Glacial Maximum 20 Kyr ago, but the consensus today maintains that the ice cover was limited due to restricted moisture sources. It is clear, however, that Northeast Siberia at one point in time hosted large ice masses, as the region is home to extensive glacial landforms of unknown age. We use cosmogenic 10Be exposure dating to study a glacial moraine complex with three well‐defined moraine ridges in the Chersky Range located in central Northeast Siberia. Our results show that the youngest and innermost moraine was emplaced toward the end of the Last Glacial Maximum, whereas the oldest and outermost moraine was emplaced during the penultimate glaciation ∼130 Kyr ago. This suggests that Northeast Siberia did not host a large ice sheet during the Late Pleistocene, and that the ice cover was limited to mountain glaciers. Satellite‐based mapping of glacial landforms confirms the existence of at least one older, more expansive glaciation that remains undated. Key Points Be‐10 exposure ages from moraines in the Chersky Range show that glaciers in central NE Siberia contracted over the last two glacial cycles Northeast Siberia hosted mountain‐centered icefields during the Late Pleistocene, but no large‐scale continental ice masses Largest ice extent in the Chersky Range predates the penultimate glacial cycle and likely occurred during the Mid‐Pleistocene super‐glacials

Glacial lake‐moraine dam systems are widespread in cold alpine environments such as the Qinghai‐Tibet Plateau (QTP). Without climate change, the lake‐dam system exhibits stably dynamic evolution on a hydrological annual cycle. However, climate change may drive subtle alterations in the system's evolution. We developed a fully coupled Thermal‐Hydraulic‐Mechanical simulation platform considering ice‐water phase change, showing robust performance under CMIP6‐derived boundary conditions. Using this platform, we simulated climate warming‐driven multiphysics responses and dam stability evolutions of a homogeneous, simplified conceptual model of the lake‐dam system. We identified critical temperature thresholds for permanently frozen area thawing and abrupt changes in dam stability of this lake‐dam system. Considering the current slope stability situations on the QTP, the SSP 5–8.5 climate warming scenario is conservatively anticipated to pose significant geological safety risks due to potential disaster chains from glacial lake failures. Our study provides insights into profound geological process evolutions driven by climate change. Plain Language Summary Sizable and numerous moraine‐dammed glacial lakes in cold alpine regions are increasingly threatened by climate change. This study simulated the long‐term (2020–2140) Thermal‐Hydraulic‐Mechanical coupling and stability evolution of a homogeneous conceptualized glacial lake‐moraine dam system under climate warming on the Qinghai‐Tibet Plateau (QTP). Two types of critical state‐transition points were identified in this conceptual model, marking shifts from quantitative to qualitative changes. A temperature rise threshold of 5.89°C indicates the onset of rapid shrinkage in permanently frozen area of the conceptual lake‐dam system. Another type of transition points occurs at 1.92°C and 4.48°C, corresponding to sharp year‐over‐year declines in spring and winter stability, respectively. A conservative estimation suggests that, if evaluated using stability reduction rate of the conceptualized model, moraine dams on the QTP with current stability factors below 1.19 in summer or 1.81 in winter, could fail after 120 years of intense climate warming. Considering the current stability situations on the QTP and geohazard chains resulting from glacial lake failure, uncontrolled global climate change would pose a severe threat to regional geological safety of QTP. The study has significant implications for assessing geological safety in periglacial environments and supports investigating coupling issues of climate change, geological processes, and human activities. Key Points Climate change‐driven multiphysics responses and stability evolution of a conceptual glacial lake‐moraine dam are depicted over the next 120 years Frozen area would rapidly retreat for nearly 10 years once the temperature rise crosses a certain threshold (5.89°C for the conceptual model) Spring and winter stability would rapidly deteriorate after surpassing certain temperature thresholds (1.92°C and 4.48°C, respectively, for the model)

The distribution of moraines in the Transantarctic Mountains affords direct constraint of past ice-marginal positions of the East Antarctic Ice Sheet (EAIS). Here, we describe glacial geologic observations and cosmogenic-nuclide exposure ages from Roberts Massif, an ice-free area in the central Transantarctic Mountains. We measured cosmogenic .sup.3 He, .sup.10 Be, .sup.21 Ne, and .sup.26 Al in 168 dolerite and sandstone boulders collected from 24 distinct deposits. Our data show that a cold-based EAIS was present, in a configuration similar to today, for many periods over the last â¼14.5 Myr, including the mid-Miocene, late Pliocene, and early to Middle Pleistocene. Moraine ages at Roberts Massif increase with distance from, and elevation above, the modern ice margin, which is consistent with a persistent EAIS extent during glacial maxima and slow, isostatic uplift of the massif itself in response to trough incision by outlet glaciers. We also employ the exceptionally high cosmogenic-nuclide concentrations in several boulders, along with multi-isotope measurements in sandstone boulders, to infer extremely low erosion rates (âª5 cm Myr.sup.-1) over the period covered by our record. Although our data are not a direct measure of ice volume, the Roberts Massif glacial record indicates that the EAIS was present and similar to its current configuration during at least some periods when the global temperature was believed to be warmer and/or atmospheric CO.sub.2 concentrations were likely higher than today.

Sustained glacier melt in the Himalayas has gradually spawned more than 5,000 glacier lakes that are dammed by potentially unstable moraines. When such dams break, glacier lake outburst floods (GLOFs) can cause catastrophic societal and geomorphic impacts. We present a robust probabilistic estimate of average GLOFs return periods in the Himalayan region, drawing on 5.4 billion simulations. We find that the 100-y outburst flood has an average volume of 33.5+3.7/−3.7 × 10⁶ m³ (posterior mean and 95% highest density interval [HDI]) with a peak discharge of 15,600+2,000/−1,800 m³·s−1. Our estimated GLOF hazard is tied to the rate of historic lake outbursts and the number of present lakes, which both are highest in the Eastern Himalayas. There, the estimated 100-y GLOF discharge (∼14,500 m³·s−1) is more than 3 times that of the adjacent Nyainqentanglha Mountains, and at least an order of magnitude higher than in the Hindu Kush, Karakoram, and Western Himalayas. The GLOF hazard may increase in these regions that currently have large glaciers, but few lakes, if future projected ice loss generates more unstable moraine-dammed lakes than we recognize today. Flood peaks from GLOFs mostly attenuate within Himalayan headwaters, but can rival monsoon-fed discharges in major rivers hundreds to thousands of kilometers downstream. Projections of future hazard from meteorological floods need to account for the extreme runoffs during lake outbursts, given the increasing trends in population, infrastructure, and hydropower projects in Himalayan headwaters.

Throughout the last cold stage, the North Atlantic region was punctuated by abrupt climate shifts and atmospheric processes propagated their effects to adjacent continents. During Heinrich Stadials, the ocean was chilled by icebergs calved from the great ice sheets. The impact of multiple temperature and precipitation regime changes on Late Pleistocene mountain glaciers and landscape development is poorly understood. Here we analyse 1,118 cosmogenic exposure ages—spanning the last 100,000 years—from glacial landforms on three continents across the Mediterranean. We evaluate their geomorphological context and stratify the record by depositional setting and geographical region. The database includes 300 dated moraines. We show that, despite cold temperatures, Heinrich Stadial aridity caused negative glacier mass balance and repeatedly stalled glacier growth across the Mediterranean. In contrast, relatively warm and humid climates between Heinrich Stadials favoured positive glacier mass balance, resulting in region-wide glacier growth and moraine formation. Our analysis supports climate model simulations of repeated and widespread Heinrich Stadial aridity in the Mediterranean basin during the last cold stage. Heinrich Stadials also saw enhanced supply of coarse debris from valley sides. The cumulative geomorphological impact of these climate shifts saw the largest moraines form at the culmination of the glacial cycle. Mountain glacier growth around the Mediterranean repeatedly stalled during cold, dry Heinrich Stadials, according to an analysis of cosmogenic isotope-dated glacial landforms from across the region.