The rapid formation of glacial lakes is one of the most conspicuous landscape changes caused by atmospheric warming in glacierised regions. However, relatively little is known about the history and current state of glacial lakes in the High Arctic. This study aims to address this issue by providing the first inventory of glacial lakes in Svalbard, focusing in particular on the post-Little Ice Age evolution of glacial lakes and their typology. To do so, we used aerial photographs and satellite imagery together with archival topographic data from 1936 to 2020. The inventory comprises the development of 566 glacial lakes (146 km²) that were still in direct contact with glaciers during the period 2008–2012. The results show a consistent increase in the total area of glacial lakes from the 1930s to 2020 and suggest an apparent link between climatic and geological factors, and the formation of specific lake dam types: moraine, ice, or bedrock. We also detected 134 glacial lake drainage events that have occurred since the 1930s. This study shows that Svalbard has one of the highest rates of glacial lake development in the world, which is an indicator of the overall dynamics of landscape change in the archipelago in response to climate change.

Glacier-fed hydrological systems in high latitude regions experience high seasonal variation in meltwater runoff. The peak in runoff usually coincides with the highest air temperatures which drive meltwater production. This process is often accompanied by the release of sediments from within the glacier system that are transported and suspended in high concentrations as they reach the proglacial realm. Sediment-laden meltwater is later transported to the marine environment and is expressed on the surface of fjords and coastal waters as sediment plumes. Direct monitoring of these processes requires complex and time-intensive fieldwork, meaning studies of these processes are rare. This paper demonstrates the seasonal dynamics of the Trebrevatnet lake complex and evolution of suspended sediment in the lake and sediment plumes in the adjacent Ekmanfjorden. We use the Normalized Difference Suspended Sediment Index (NDSSI) derived from multi-temporal Sentinel-2 images for the period between 2016–2021. We propose a new SSL index combining the areal extent of the sediment plume with the NDSSI for quantification of the sediment influx to the marine environment. The largest observed sediment plume was recorded on 30 July 2018 and extended to more than 40 km² and a SSL index of 10.4. We identified the greatest sediment concentrations in the lake in the beginning of August, whereas the highest activity of the sediment plumes is concentrated at the end of July. The temporal pattern of these processes stays relatively stable throughout all ablation seasons studied. Sediment plumes observed with the use of optical satellite remote sensing data may be used as a proxy for meltwater runoff from the glacier-fed Trebrevatnet system. We have shown that remote-sensing-derived suspended sediment indexes can (after proper in situ calibration) serve for large scale quantification of sediment flux to fjord and coastal environments.

Small Arctic coastal catchments and coastal lagoon systems are some of the most vulnerable to climate change. Glacial retreat and the development of glacial lakes and drainage systems provide opportunities for hazardous events such as GLOFs. We observe that the stability of lagoons and their associated barriers are controlled by the frequency and magnitude of storms approaching the coasts, access to sediment supplies and resilience to sea-level rise. Based on multidecadal remote sensing data, we were able to identify the rate of glacial recession, the development of glacial lakes, vegetation response to climate change and a GLOF event, and shoreline and lagoon responses to the environmental shifts within the small catchment. Here we present an example of lagoon system evolution where a glacial outburst flood exerted significant control over lagoon drainage and coastal barrier stability.

Rapid changes of glacial lakes are among the most visible indicators of global warming in glacierized areas around the world. The general trend is that the area and number of glacial lakes increase significantly in high mountain areas and polar latitudes. However, there is a lack of knowledge about the current state of glacial lakes in the High Arctic. This study aims to address this issue by providing the first glacial lake inventory from Svalbard, with focus on the genesis and evolution of glacial lakes since the end of the Little Ice Age. We use aerial photographs and topographic data from 1936 to 2012 and satellite imagery from 2013 to 2020. The inventory includes the development of 566 glacial lakes (total area of 145.91 km²) that were in direct contact with glaciers in 2008–2012. From the 1990s to the end of the 2000s, the total glacial lake area increased by nearly a factor of six. A decrease in the number of lakes between 2012 and 2020 is related to two main processes: the drainage of 197 lakes and the merger of smaller reservoirs into larger ones. The changes of glacial lakes show how climate change in the High Arctic affect proglacial geomorphology by enhanced formation of glacial lakes, leading to higher risks associated with glacier lake outburst floods in Svalbard.

The study investigates glacial lakes in Svalbard, examining examples from the forelands of Gåsbreen, Crammerbreen, Knivseggbreen, Neppebreen and Ragnarbreen, each representing different classifications of glacial lakes, including ice-dammed, frontal moraine-dammed and medial moraine-dammed. These lakes serve as key indicators of ongoing climate change and the effects of deglaciation processes in polar landscapes. Quantitative analyses reveal notable differences among the selected glacial lakes. For instance, Goësvatnet experienced cyclical glacial lake outburst floods (GLOFs), with a recorded volume of 666,389 m3 during one event. Conversely, the lake on the Ragnarbreen foreland, while stable, has not encountered any GLOFs, indicating a distinct response to deglaciation compared with other examples. Hydrographic and surface analyses, conducted using digital elevation models (DEMs) and remote sensing data, provide insights into the morphological characteristics and dynamics of the glacial lakes and surrounding landscapes. Longitudinal profiles of glaciers show varied terrains, with Ragnarbreen exhibiting the least variability due to its source zone on the ice cap, while Crammerbreen presents diverse features, including tectonic faults resulting in icefalls with slopes >35°. By including multiple glacial lakes across different locations and classifications, this study offers a comprehensive understanding of the diverse responses of glacial lakes to deglaciation processes in Svalbard, shedding light on the complex interactions between glaciers, lakes and changing environmental conditions in the Arctic region.

The retreat of glaciers in response to climate warming leads to substantial changes not only in their mass balance, size and runoff but it also impacts their proglacial zones. A common characteristic of these proglacial changes is the development of glacial lake systems, which serve as meltwater and sediment reservoirs and become new elements in Arctic paraglacial landscapes. This paper investigates the evolution of a unique glacial lake system that has developed in the proglacial zone of the glacier system Cramerbraene in Svalbard since the termination of the Little Ice Age.Our results indicate that the first glacial lakes appeared in the foreland of Crammerbreane in the late 1950s and early 1960s. Since then, the lake system has steadily increased in area concurrently with progressive retreat of Crammerbreane. In 2014, the first documented dam breaching of the terminal moraine occurred, leading to a glacial lake outburst flood (GLOF) event, which resulted in a loss of the lake area by 0.08 km2. After this event, the lake area began to steadily increase again reaching its largest surface area in its development history in 2019: 0.44 km2. In September 2019, a second and larger GLOF event occurred, reducing the lake area by 0.23 km2 (~50%) within nine days. Recent satellite and aerial imagery indicates that the described lake system has been steadily draining since the 2019 GLOF event. More importantly, as a result of these two documented catastrophic glacial runoffs, the geomorphology in the foreland of Crammerbreane has been reworked, leading to changes in the course of the river channel that transports glacial water into Recherchefjorden.            These findings suggest that glacial lake systems in Svalbard play an increasingly important role in paraglacial Arctic landscape transformation, not only as glacial water and sediment storage reservoirs but also as active agents of downstream geomorphological changes through episodic catastrophic GLOF events.            This work was supported by Svalbard Integrated Arctic Earth Observing System [Airborne remote sensing campaign 2021] and the Research Council of Norway [333199].