Dr Chris Stringer

The proglacial landscapes of Antarctica offer critical insights into past and ongoing deglaciation processes and the impacts of climate change. This study presents the first geomorphological map of the proglacial part of Stansbury Peninsula (Rip Point) and Cariz Cabo Cape in the northern part of Nelson Island. We identify and characterise a variety of glacial, proglacial, paraglacial, and periglacial landforms using high-resolution drone imagery, fieldwork, and geological data. The defined landforms presented reflect a complex interplay of erosional and depositional processes shaped by multiple glacial advance-retreat cycles since the Last Glacial Maximum, with evidence for significant glacial activity during the Holocene. The presence of hyaloclastite and crystalline erratic boulders further contributes to the reconstruction of glacial dynamics in the region. Our findings provide a crucial dataset and baseline for studies on future Antarctic deglaciation, periglacial processes, and the expansion of proglacial landscapes driven by ongoing climate change.

Accelerated glacier mass loss across the Antarctic Peninsula has consequences for sea level rise and local ecology. However, there are few direct glaciological observations available from this region. Here, we reveal glacier changes on the James Ross Archipelago between 2010 and 2023. The median rate of glacier area loss (remote-sensing derived) increased over the study period, with the most significant changes observed in smaller glaciers. In-situ measurements show that ablation has identified a tripling of the frontal velocity of Kotick Glacier in 2015, which combined with terminus surface elevation gains (bulging), suggests that this is the first surge-type glacier identified in Antarctica from velocity and surface elevation change observations. We contend that the glacier recession rate has increased due to increased air temperatures (0.24 ± 0.08 °C yr-1, 2010 to 2023), decreased albedo, and glacier elevation change feedbacks. These processes could decrease glacier longevity on the archipelago. Future research should prioritise monitoring albedo and rising equilibrium-line altitudes and identify glaciers most vulnerable to rapid future mass loss.

The termini of Icelandic glaciers are highly dynamic environments. Pronounced changes in frontal ablation in recent years have consequently changed ice dynamics. In this study, we reveal the inter-seasonal dynamics of the Kvíárjökull ablation zone and proglacial zone using ArcticDEM and Sentinel-2 images acquired between 2011 and 2021 and intra-seasonal dynamics with repeated UAV surveys during summer 2021. Average glacier surface velocity in the ablation zone ranged from 51 m year−1 in 2015 up to 199 m year−1 in 2018, with maxima within the axial zone of the glacier and minima on the glacier edges. Coincidentally, and in accordance with glacier retreat/advance, the ice-marginal proglacial lake fluctuated in its area, and we interpret that it was also a key factor in the development of the glacier terminus morphology. A complex spatial pattern of glacier surface elevation changes, including thickening in the frontal true left margin of the terminus, is interpreted to be due to variable subglacial topography, relatively fast ice flow from the accumulation zone and an insulating effect of glacier surface debris cover. In contrast, the true right (southern) part of the glacier terminus experienced thinning and retreat/disintegration also during the 2021 summer season, which we attribute to enhanced frontal ablation connected to the intrusion of lake water into the crevassed glacier terminus. Overall, this study suggests that where glaciers are developing ice-marginal lakes complex patterns of glacier dynamics and mass loss can be expected, which will confound understanding of the short-term evolution of these environments.

Abstract. Continental-scale land cover information is essential to furthering our understanding of the terrestrial environment, atmosphere and climate change. Several global land cover products have been released in recent years but they typically do not include Antarctica. The lack of land cover data in Antarctica is concerning because mountain glaciers and icecaps there have been losing mass at a rate well above the global average, leading to expansion of proglacial regions. Proglacial regions comprise transient land cover types with high rates of geomorphological activity that delivers sediment into the Southern Ocean and supports its rich biodiversity. With Antarctic mountain glaciers and icecaps projected to lose more mass in the coming decades, and active layer soils expected to increase in thickness, it is timely to establish a baseline land cover dataset for Antarctica with which future classifications can be compared. Here, we use Landsat-8 Operational Land Imager (OLI) images to classify six proglacial regions of Antarctica at 30 m resolution, with an overall accuracy of 77.0 % for proglacial land classes. We conducted this classification using an unsupervised K-means clustering approach, which circumvented the need for training data and was highly effective at picking up key land classes, such as vegetation, water, and different sedimentary surfaces. We have highlighted the spatial pattern in land cover and emphasise a need for more and higher quality field data. The land cover maps produced from this paper are available at: Stringer, C. (2022). Contemporary (2016–2020) land cover classification across West Antarctica and the McMurdo Dry Valleys (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/5A5EE38C-E296-48A2-85D2-E29DB66E5E24.

Increasing temperatures in Antarctica have resulted in the enlargement of proglacial regions on the Antarctic Peninsula, following glacier melt. This melt has increased river activity yet direct runoff measurements remain scarce in Antarctica, despite it acting as a proxy for glacial ablation. Here, we present discharge and water temperature data from 2013 for three streams on Vega Island and discuss their relationship with air temperature. The average discharge at the largest stream was 0.523 m3s−1 with a maximum of 5.510 m3s−1 – among the highest recorded in Antarctica. The rivers continued to flow even when temperatures dropped to −7°C, indicating that a large proportion of the total runoff originated sub-glacially. This is supported by the one-day time lag between air and water temperatures. Using river discharge as a proxy, we measured 124.5 ± 14.4 mm w.e. of ablation. This indirect measurement proved an effective tool to complement classic glaciological observations.

Land cover information is essential for understanding Earth surface processes and ecosystems. Here, we use K-means clustering to classify Landsat 8 Operational Land Imager (OLI) images covering six proglacial sites of sub-Antarctic islands, the Antarctic Peninsula, and the McMurdo Dry Valleys at 30-m resolution. We quantify spatial patterns of water, bedrock, vegetation, and sediments to an accuracy of 77 percent. Vegetation is most abundant on South Georgia (7 percent of the proglacial area) and the South Shetland Islands (1 to 2 percent). Furthermore, we use change vector analysis (CVA) to discriminate landcover change in the twenty-first century. A latitudinal pattern is evident in ice loss and proglacial landscape change; for example, loss of ice on South Georgia and proglacial landcover change is two orders of magnitude greater than in the McMurdo Dry Valleys. Four of the studied sites had similar landscape stability (64 to 68 percent unchanged), with Alexander Island an exception (50 percent change) due to recent enhanced glacier melt. Overall, we show how landcover of proglacial regions of the climaticallysensitive sub-Antarctic and Antarctica has changed since 2000, with a CVA accuracy of 80 percent. These findings inform understanding of geomorphological activity and sediment and nutrient fluxes and hence terrestrial and marine ecosystems.

The Antarctic Peninsula is now warming again after a hiatus in temperatures, and ice masses are receding at an enhanced rate, resulting in the enlargement of proglacial regions. Despite the importance of proglacial regions as sediment sources in polar environments, few studies focus on the Antarctic and sub-Antarctic fluvial sediment dynamics and even fewer have explored the spatio-temporal variability in sediment delivery or compiled a comprehensive source-to-sink description of sediment transportation. Proglacial rivers are shaped by the interplay of glacial meltwater, which erodes, transports, and deposits sediment, and hillslope activity, which provides new sediment to the riverine system during mass transport events. Active layer soils can be an additional source of water and sediment when ground temperatures are above freezing; particularly in catchments with low glacier cover. In this study, we aim to discuss how different environmental factors, such as air temperature, active layer thaw, and precipitation affect sediment yields in two rivers on James Ross Island, Antarctica. Based on field data collected at the start of 2022, we used a multi-disciplinary approach to quantify the spatio-temporal variability in sediment yields across the river catchments of the Algal and Bohemian Streams and their key environmental controls. Additionally, we discuss how X-ray fluorescence and infrared spectroscopy have provided an insight into how sediment composition and, potentially, source change downstream in each stream. We estimate that the annual sediment yield for the Bohemian Stream in the austral summer of 2021/2022 was 400 tonnes/year/ km2 and 530 tonnes/year/ km2 for the Algal Stream. While the Algal Stream has a higher estimated yield, its daily sediment yield values are highly variable and the Bohemian Stream typically exports more sediment into the Southern Ocean. Our results show that the active layer is an important driver of sediment yield variability in the Algal catchment. In contrast, sediment yield from the Bohemian catchment is more sensitive to air temperature. Both catchments are sensitive to changes in precipitation. The differences in sediment yield from the two catchments likely stem from differences in glacier and snowfield coverage. These sediment yield values are exceptionally high by Antarctic standards, and are comparable to that from catchments on Svalbard, although they remain low by global standards. Our identification of the controls on sediment yield provides insight into how other fluvial sedimentary systems across the Antarctic Peninsula could respond as glaciers lose mass in a warming climate.

This paper introduces a new method for the simultaneous determination of lead, aluminum, and iron in plant samples using high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ETAAS). The method is suitable for covering a wide range of concentrations for all three elements, by utilizing two spectral lines for Al and employing the wavelength-selected absorbance (WSA) approach, which combines the reading of absorbance signals at both the central and wing parts of the spectral lines. The method was validated against certified reference materials and was then applied in a large-scale analysis of Antarctic flora collected from Nelson Island in the South Shetland Islands, Antarctica. The method was found to be a useful biomonitoring tool for assessing Pb pollution in various plant materials, including lichens, mosses, grass and mushrooms, while Al and Fe contents may serve as normalizing elements in calculations of environmental indices. The observed Pb levels in lichens (median content 0.19 mg Pb/kg) were lower than those reported in other Antarctic regions. These findings indicate that the Stansbury Peninsula on Nelson Island is relatively unaffected by local pollution, compared to other Antarctic regions, and that the data might serve as an example of background levels in the South Shetland Islands.

Proglacial regions are enlarging across the Antarctic Peninsula as glaciers recede in a warming climate. However, despite the increasing importance of proglacial regions as sediment sources within cold environments, very few studies have considered fluvial sediment dynamics in polar settings and spatio-temporal variability in sediment delivery to the oceans has yet to be unravelled. In this study, we show how air temperature, precipitation, and ground conditions combine to control sediment loads in two catchments on James Ross Island, Antarctica. We estimate that the sediment load for the Bohemian Stream and Algal Stream over the 50 day study period, the average sediment load was 1.18 ± 0.63 t km−2 d−1 and 1.73 ± 1.02 t km−2 d−1, respectively. Both catchments show some sensitivity to changes in precipitation and air temperature, but the Algal catchment also shows some sensitivity to active layer thaw. The downstream changes in sediment provenance are controlled by underlying lithology, while differences in sediment load peaks between the two catchments appear to be primarily due to differing glacier and snowfield coverage. This identification of the controls on sediment load in this sub-polar environment provides insight into how other fluvial systems across the Antarctic Peninsula could respond as glaciers recede in a warming climate.

Global glacier mass loss is causing expansion of proglacial landscapes and producing meltwater that can become impounded as lakes within natural topographic depressions or ‘overdeepenings’. It is important to understand the evolution of these proglacial landscapes for water resources, natural hazards and ecosystem services. In this study we (i) overview contemporary loss of glacier ice across the Southern Alps of New Zealand, (ii) analyse ice-marginal lake development since the 1980s, (iii) utilise modelled glacier ice thickness to suggest the position and size of future lakes, and (iv) employ a large-scale glacier evolution model to suggest the timing of future lake formation and future lake expansion rate. In recent decades, hundreds of Southern Alps glaciers have been lost and those remaining have fragmented both by separation of tributaries and by detachment of ablation zones. Glaciers with ice-contact margins in proglacial lakes (n > 0.1 km2 = 20 in 2020) have experienced the greatest terminus retreat and typically twice as negative mass balance compared to similar-sized land-terminating glaciers. Our analysis indicates a positive relationship between mean glacier mass balance and rate of lake growth (R2 = 0.34) and also with length of an ice-contact lake boundary (R2 = 0.44). We project sustained and relatively homogenous glacier volume loss for east-draining basins but in contrast a heterogeneous pattern of volume loss for west-draining basins. Our model results show that ice-marginal lakes will increase in combined size by ~150% towards 2050 and then decrease to 2100 as glaciers disconnect from them. Overall, our findings should inform (i) glacier evolution models into which ice-marginal lake effects need incorporating, (ii) studies of rapid landscape evolution and especially of meltwater and sediment delivery, and (iii) considerations of future meltwater supply and water quality.