Marcelo Fernandes

The Greenland Ice Sheet (GrIS) is a key component of the global climate system, and constraining the Holocene deglaciation history of its land-terminating margins is key to understanding its sensitivity to climate forcing. Here, we provide insights into landscape evolution and environmental change on the Qinguassarsuaq Peninsula, Central–West Greenland 69°N, 50°W, where we used high-resolution geomorphological surveys and extensive field mapping to identify features formed during ice retreat. We divided the peninsula into four principal geomorphological units: elevated uplands, glacial valleys, nunataks, and active glacial outlets. We then established the timeline of deglaciation using ¹⁰ Be cosmic-ray exposure (CRE) dating of 20 samples collected from well-preserved glacially polished bedrock and stable moraine boulders, together with four optically stimulated luminescence (OSL) ages from glaciofluvial terraces formed by ice-marginal damming. Geomorphological evidence indicated that ice occupied the valleys and plateaus of the peninsula and overtopped nearby summits during the Late Pleistocene. Four OSL ages from lacustrine terraces spanning 20.8–8.3 ka indicated deglaciation of the area by the Early Holocene. As the GrIS thinned at this time, ice retreat confined the ice mass to the eastern fringe of the peninsula, where deglaciation progressed between ~8.0 and 6.5 ka, also exposing the nunataks that today rise above the ice sheet. Near the present glacier front, CRE ages of ~0.9–1.0 ka from several lateral and frontal moraines suggested a general absence of major Neoglacial re-advances, apart from the last millennium, including ice expansion during the late Mediaeval Warm Period to the early Little Ice Age. Our results underscore the importance of integrating geomorphological mapping with multiple dating techniques to refine reconstructions of the GrIS’s complex deglaciation history.

River management is often driven by energy production, irrigation crops, and flood mitigation, largely enabled by widespread dam construction. However, river damming has brought severe environmental consequences for river dynamics, including morphological changes, hydrological regime, and interruption of the sediment cascade. These physical changes have profound impacts on the ecology of numerous fish species, particularly highly migratory ones, which, together with parallel drivers, led to an 85% reduction in world freshwater species populations since 1970. This work aims to provide a methodological framework for identifying priority rivers within the Portuguese strategy for improving river connectivity affected by obsolete dams and weirs under the European Nature Restoration Law.The official fish dataset of the Portuguese Institute for Nature Conservation and Forests was first used, which included >20,000 occurrences for 61 fish species between 2010 and 2020. Each species was classified according to the following variables: species origin (native, exotic), conservation status (Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern, Data Deficient, Not Evaluated), phenology (diadromous, potamodromous, resident), socioeconomic importance (very high, high, low significance), and endemism degree (Iberian or Lusitanian endemism). A score was attributed to each criterion, and the species index was calculated using Equation 1. Finally, to ensure functional connectivity to the ocean, we have included the lowermost segment of the main rivers up to the first insurmountable dam.Equation 1: R = a · (0,25 · Xi + 0,40 · Xii + 0,20 · Xiii + 0,15 · Xiv)Where the species index (R) resulted from the multiplication of the origin coefficient (α: species origin) with the weighted mean of the variables (Xi: conservation status; Xii: phenology; Xiii: socioeconomic importance; Xiv: endemism degree).In parallel, hydrographic modelling was carried out using the Strahler model to ensure full representation of the Portuguese river network and a hierarchy adjusted to the sub-basin scale. The sub-basins were selected based on the 4th, 5th, 6th, and 7th Strahler hierarchies, and the excluded areas in the main river margins were included using the 8th hierarchy. For each sub-basin, the arithmetic mean of the species index was calculated within the Geographical Information System environment. The prioritization for river restoration was based on the upper quartile means for each hydrological region independently.All rivers within the prioritized sub-basins were divided into segments according to the 3rd cycle of River Basin Management Plans and the Water Framework Directive, as provided by the Portuguese Environmental Agency. Each segment was classified according to water quality (chemical status and ecological quality), and segments were excluded if these criteria were simultaneously negative. At this stage, the Strahler 3rd-order streams connected to selected segments were included to guarantee ecological coherence in fluvial connectivity. The presence of a protected area (Natura 2000) and the density of transversal barriers were also evaluated. Finally, the national barrier dataset was updated using satellite imagery to identify new barriers.In total, 77 rivers, encompassing ca. 6500 km at the sub-basin scale, were prioritized within the Portuguese strategy to improve river connectivity affected by obsolete dams and weirs.

The Pyrenean Range was intensively shaped by glaciers during the Late Pleistocene glacial cycles. The chronology of past glacial oscillations has been increasingly unveiled during the last decade, although comprehensive reviews of glacial evolution during the Late Pleistocene are still missing. Here, we review the glacial and periglacial chronology existing in the Upper Garonne Basin, which is organized in three moraine complexes at (i) the Loures-Barousse-Barbazan Basin (LBBB), (ii) valleys, and (iii) glacial cirques. The most external moraine preserved at 420–480 m asl in the LBBB unveiled the Maximum Ice Extent from the Penultimate Glacial Cycle during the MIS-6, as indicated by Cosmic-Ray Exposure ages of ca. 130 ka. During the Last Glacial Cycle, the Garonne paleoglacier reached the LBBB once again before 40 and 32 cal ka BP, marking the local Last Glacial Maximum in the Pyrenees. However, by the time of the global Last Glacial Maximum, the slopes of the Marignac Basin were already deglaciated, as evidenced by two polished surfaces dated to 21–24 ka at elevations of 520–540 m asl. Thereafter, glaciers shrank upvalleys during the last deglaciation, as shown by polished surfaces at 1860–1900 m asl in the Ruda Valley dated to 14–15 ka. The glacial retreat within the valleys was interrupted by two glacial advances or standstills during the second half of the Bølling–Allerød Interstadial, around 13.5 and 13.0 ka. During the Younger Dryas, glaciers advanced to elevations of 2370–2470 m asl within the glacial hollows, where moraines stabilized at 12.9 and 12.6 ka. Following this advance, paraglacial processes intensified, transforming the final debris-free glaciers into debris-covered glaciers and rock glaciers. The warming at the onset of the Holocene prompted the final stabilization of boulders around 11.9 ka in the relic rock glacier of Lòcampo Cirque and 7.2 ka in the debris-covered glacier of Bacivèr Cirque. This synthesis highlights the potential of the Upper Garonne Basin to serve as a key reference area for understanding the spatiotemporal evolution of glacial and periglacial dynamics in the Pyrenees throughout the Late Pleistocene and the Holocene.

Geomorphological evidence of cold environments in the Drakensberg, southern Africa, has long been debated. Previous work, based on geomorphological, micromorphology and modelling techniques has suggested glacial conditions above ca. 3200 m a.s.l. However, this has been challenged due to the unclear glacial genesis of geomorphological features. This work aims to provide new evidence of past glacial and periglacial conditions in the Drakensberg.Our aim is addressed by mapping a geomorphological sketch (1:25000) near the Sani Pass, Drakensberg, based on a 0.5 m resolution Digital Surface Model and an orthomosaic derived from Pléiades satellite imagery, and validated by field reconnaissance work. Specifically, the areas of the Sehonghong plateau, the upper reaches of the KwaNtuba cutback, and the Mangaung catchment, were investigated with several uncrewed aerial vehicle surveys for a detailed geomorphological mapping (1:5000). Finally, we applied Schmidt-Hammer exposure-age dating (SHD) and collected sixteen samples for Cosmic-Ray Exposure (CRE) dating from well-preserved features suggesting glacial and periglacial dynamics, which are currently being processed.The Sehonghong plateau is located adjacent to the Great Escarpment, between 3400 and 3290 m a.s.l., and has gentle NE-facing slopes. The highest terrain is characterised by the widespread occurrence of weathered surfaces. The bedrock surfaces are littered with highly weathered and eroded ‘shattered’ debris, which provides the source for block fields and which have been reworked by periglacial processes, as evidenced by large sorted stone circles. At the plateau floor, degraded earth hummocky terrain and turf exfoliation areas are examples of wetland degradation. The different landforms suggest wind and seasonal frost conditions are the major geomorphic agents.The KwaNtuba cutback faces ESE from 3350 to 2870 m a.s.l and encompasses steep slopes along the SW-NE-oriented Great Escarpment. The cutback headwall is shaped by an amphitheatric feature with 220 m high (3340-3120 m a.s.l) steep rock-plucked surfaces. From the foot of this rock face to the valley bottom, a 400 m wide and 200 m long deposit covers the slope. Here, five SE-facing elongated ridges developed along the deposit from 3120 to 2870 m a.s.l. The deposit is composed of subangular to angular metric-sized boulders embedded in a sandy matrix. The geomorphological context and sedimentological features suggest traces of ice flux dynamics, typically observed in debris-covered glaciers.In the Mangaung catchment, two S-facing cirque-shaped basins were analysed. The eastern one has two well-developed parallel ridges at ca. 3210-3110 m a.s.l with subangular-subrounded metric-size boulders embedded in the sandy matrix that are considered lateral moraines. The centre of the basin has polished surfaces with striations suggesting former temperate subglacial abrasion. At the bottom of the western basin, a 1 km long and 60 m wide block stream developed between 3160 and 2980 m a.s.l. It has elongated ridges and is composed of matrix-free boulders whose central axis preserves alignment patterns downvalley.The climatic conditions under which these features developed will be revealed in future results from CRE dating, palaeoclimate simulations and palaeoglacier modelling.

The Greenland Ice Sheet is highly sensitive to climate change, leading to significant retreat along its edges. This rapid ice loss contributes to rising sea levels and impacts the Earth's climate stability. Understanding the extent of recent glacier retreat is crucial in order to determine if it is unprecedented or within ranges of natural variability. Palaeoenvironmental studies aim to identify past glacial phases and landscape changes using advanced dating methods such as cosmic ray exposure (CRE) dating. In NE Greenland, CRE dating has helped establish the timing of glacial oscillations, yet a comprehensive understanding of glacial fluctuations during specific periods still needs to be developed. This study aims to chronologically constrain the postglacial landscape evolution of two NE Greenland valleys from the Young Sund–Tyrolerfjord area (74°N, 20–25°E) from the onset of deglaciation and throughout the Holocene to better understand glacial and postglacial changes. The chronological framework relies on 27 ¹⁰Be cosmic‐ray exposure ages that constrain our interpretation of the geomorphological features in both valleys. Inconsistencies were observed in the ages dataset, highlighting potential bias associated with nuclide inheritance and post‐glacial dynamics. Despite limitations, the CRE results confirm the general pattern observed in NE Greenland: (i) major deglaciation and disconnection of glaciers from the main glacial systems during the Lateglacial and Early Holocene with a rapid but not homogeneous deglaciation within the range from ~14.3 to 11.9 ka; (ii) no evidence of glacial activity during the Middle Holocene, probably associated with the withdrawn position of the ice masses’ fronts; and (iii) glacier expansion during the Late Holocene, with a Little Ice Age advance as the last significant period of glacial regrowth.

In the highest tributaries of the Upper Garonne Basin, Central Pyrenees, cirques up to 2600 m a.s.l. were already deglaciated by 15–14 ka. The long‐term deglaciation during Termination‐1 (T‐1) was interrupted by glacial advances within the cirques during the Bølling–Allerød (B‐A) interstadial and the Younger Dryas stadial. The cirques preserve a variety of glacial and periglacial landforms whose chronologies are poorly known. This study is focused on the Lòcampo cirque (42°38′06″N and 0°59′10″E), Upper Garonne Basin, where a detailed geomorphological map and ¹⁰Be terrestrial cosmic ray exposure (CRE) dating allowed us to constrain the chrono‐sequence between the glacial and periglacial domains. In the small Lòcampo cirque, a glacier formed a cirque moraine between 2200 and 2300 m a.s.l., which surrounds a relict rock glacier encompassing several transversal ridges. Additionally, longitudinal ridges typically observed in debris‐covered glaciers are preserved between the moraine and the rock glacier. The eight‐sample data set of CRE ages indicates the formation of the cirque moraine during the second half of the B‐A, by 13.2±1.1 ka. Exposure ages from the rock glacier boulders show a range between 13.6±0.9 and 11.9±0.7 ka, which did not allow its formation to be chronologically constrained. Therefore, the environmental evolution following the moraine stabilization could follow the formation of a debris‐covered glacier at the bottom of the Lòcampo cirque, with the subsequent formation of the rock glacier. After the rock glacier formation, its front rapidly ceased at 13.6±0.9 ka, while the upper ridges gradually stabilized until it became definitively relict at 11.9±0.7 ka or afterwards. These results show evidence of the complex glacial to periglacial transition that needs more robust chronological data sets to better understand the role of climate forcing and local topography during the deglaciation in mid‐latitude mountain environments.

The spatial and temporal patterns of Holocene glacial oscillations in most currently ice-free areas of Antarctica remains unknown. This work focuses on the recent deglaciation in the northern sector of the Fildes Peninsula, King George Island, northern Antarctic Peninsula. The ice cap covering ca. 90% of the island has receded since the last glacial maximum and exposed ca. 29 km2 of ice-free land. We reconstruct its glacial history based on a dataset of 12 36Cl exposure ages obtained through Cosmic-Ray Exposure (CRE) dating of moraine boulders, polished surfaces and erratic boulders surrounding the peninsula’s northern plateau. Results reveal that the deglaciation of the northern Fildes Peninsula took place during the Holocene Thermal Maximum at 7-6 ka, when warm conditions promoted a massive glacial retreat. The present arrangement of ice-free areas was in place by 6 ka. Small cirque moraines suggest the subsequent occurrence of favourable climate conditions for glacial expansion fed by intense snow deflation at 4.6 and 1 ka at the foot of the northern plateau. The deglaciation pattern of the Fildes Peninsula resulted from the combined shrinkage of different ice masses, rather than of the long-term retreat of the King George Ice Cap. No evidence of glacier expansion during more recent cold periods (i.e. the Little Ice Age) was found. These results fit well with regional deglacial histories inferred from lacustrine sediments and raised beaches and complement the existing chronological framework to help better understand the peninsula’s Holocene geoecological dynamics.

The Upper Garonne Basin hosted the largest glacier of the Pyrenees during Late Pleistocene glaciations. Glacial retreat started after the Last Glacial Maximum (20-19 ka) of the last glacial cycle, and by the onset of the Bølling–Allerød interstadial (B-A; 15-14 ka) ice masses were already confined within the glacial cirques and highest valleys. In the Aran Valley, headwaters of the Garonne Basin, the low glacial cirques (with maximum elevations of ~2600 m) preserve a significant variety of glacial and periglacial landforms of unknown age. This study focuses in the Locampo Cirque, where we conducted a detailed geomorphological mapping of the glacial and periglacial landforms and dated a set of 8 samples using 10Be Cosmic-Ray Exposure (CRE). This approach allowed to establish the chronology and identify the mechanisms involved in the transition from glacial to periglacial dynamics. CRE ages reveal that the external moraine closing the cirque (2210-2335 m) probably formed during the second half of the B-A at 13.7 ± 1.5 ka. Subsequently, glaciers retreated, and a rock glacier developed inside the external moraine (2210-2310 m) during the paraglacial phase. The final stabilization of this rock glacier most likely occurred during the Younger Dryas (YD)-Holocene transition, at 11.9 ± 0.7 ka. These results report the first chronology on the formation of rock glaciers in the northern slope of the Central Pyrenees and confirm the pattern observed in other mid-latitude mountains, showing that the final deglaciation occurred during the (cold but dry) YD, accompanied by the development and stabilization of rock glaciers.

The Upper Garonne Basin constituted the longest glacier of the Pyrenean ice field during the Late Pleistocene. From the peaks of the axial Pyrenees that exceed 2,800-3,000 m, the Garonne palaeoglacier flowed along ~80 km northwards during the major glacial advances reaching only 420-440 m. This palaeoglacier reached the Pyrenean foreland, at the Loures-Barouse-Barbazan basin (LBBB) where it formed a terminal moraine complex that is examined in this work. We have constrained the timing of the maximum glacial extent as well as the onset of the deglaciation from the end of the Last Glacial Cycle (LGC) based on the geomorphological observations and a 12-sample dataset of 10Be Cosmic-Ray Exposure (CRE) ages. There are two moraine systems at the LBBB, where the first is composed of weathered ridges at the outermost part of the basin and the second encompasses well-preserved ridges stretching across the innermost part of the basin. Chronological data shows that the external moraines were abandoned by the ice at the end of the Penultimate Glacial Cycle (PGC) and the onset of the Eemian Interglacial, at ~129 ka. The few existing reliable boulders to date in the internal moraine showed inconsistent ages as they were probably affected by post-glacial processes and therefore, this work adds no evidence of subsequent glacial advances or standstills during the LGC in the LBBB. However, the terminal basin was already deglaciated during the global Last Glacial Maximum (GLGM) at 24-21 ka, as revealed by exposure ages from polished surfaces at the confluence of the Garonne-la Pique valleys, 13 km south of the entrance of the LBBB. This study introduces the first solid CRE database in the Pyrenees for the glacial advance that occurred during the PGC and provides also new evidence from the GLGM when the Garonne palaeoglacier had already significantly shrunk.