Louise Steffensen Schmidt

• Kleber, Gabrielle E.; Mannerfelt, Erik Schytt; Schloemer, Stefan; Senger, Kim; Magerl, Leonard & Hensgens, Geert [Vis alle 11 forfattere av denne artikkelen] (2026). Subglacial geology and thermal conditions regulate methane emissions from Svalbard glaciers. Nature Communications. 17, s. 1–12. doi: 10.1038/s41467-026-77190-z. Fulltekst i vitenarkiv Vis sammendrag

  Melt rivers from valley glaciers and ice sheets release methane by transporting microbial or geologic methane from beneath glaciers, making it available for atmospheric emission. However, the mechanisms and magnitude of such methane release remain poorly understood due to limited studies. Here, we show how subglacial geology and glacier thermal conditions control methane supersaturation in meltwaters from 19 valley glaciers across central Svalbard. We find that all sampled meltwaters are supersaturated with methane, with peak concentrations up to 425-times atmospheric equilibrium. The carbon isotopic compositions of the methane and the presence of ethane and propane indicate that the methane is largely of thermogenic origin. Ground-penetrating radar surveys show that the extent of temperate ice at the glacier bed plays a critical role in facilitating methane acquisition, particularly in regions underlain by organic-rich, shale-dominated geological formations. This mechanistic insight is relevant for glaciated regions worldwide with organic-rich geology and suggests that accelerated glacier melt may amplify methane mobilization from beneath glaciers.

• Alexander, Andreas; Piermattei, Livia; Assmy, Philipp Kurt Wolf; Popp, Andrea; Zhao, Ken & Parra, Nicolas Valiente [Vis alle 20 forfattere av denne artikkelen] (2026). The Impact of Subglacial Drainage System Evolution and Glacier Lake Outburst on Arctic Fjord Macronutrient Dynamics. Journal of Geophysical Research (JGR): Biogeosciences. ISSN 2169-8953. 131(7). doi: 10.1029/2023jg007969. Fulltekst i vitenarkiv Vis sammendrag

  Global warming is amplified in the Arctic, accelerating glacier melt and freshwater runoff. At tidewater glaciers, runoff typically enters fjords at depth and generates buoyancy‐driven circulation that enhances glacier‐ocean exchanges of energy and matter, influencing macronutrient delivery and marine primary production. However, most studies lack the temporal resolution to capture low‐frequency, high‐magnitude events, leaving their impacts poorly understood. Here, we combine glacier observations with high‐frequency fjord and glacier‐lake sampling to examine the 2021 glacier lake outburst flood (GLOF) from Lake Setevatnet into Kongsfjorden (Svalbard). We show how evolving subglacial conditions before and during the GLOF shaped macronutrient supply to the inner fjord through both direct runoff and entrainment of bottom waters. Early in summer, nutrient delivery was dominated by direct runoff, supplying nitrate (NO 3 − ) and silicate via an inefficient drainage system. As the melt increased, an efficient system formed, generating a subglacial plume and initiating buoyancy‐driven circulation that entrained nutrient‐rich deep water. Despite high NO 3 − lake concentrations, the flood barely affected fjord NO 3 − levels. Instead, it produced a seasonal maximum in nitrite (NO 2 − ). Comparisons with conservative mixing estimates and nitrogen budget analyses reveal a non‐conservative nutrient signal. Although sedimentary sources cannot be excluded, the timing and spatial pattern of the NO 2 − anomaly suggest subglacial modification during floodwater transit. These findings indicate that Kongsfjorden functions as a summer nitrogen sink, partly shaped by subglacial transformations. Overall, nutrient delivery from tidewater glaciers depends not only on runoff volume but also on the subglacial drainage system characteristics, which evolve during high‐magnitude events such as GLOFs.

• Gajek, Wojciech; Nanni, Ugo; Gholami, Ali; Harcourt, William D.; Pearce, Danni & Schmidt, Louise Steffensen (2026). Surface Crevasse Evolution Observed Using Matched Field Processing and Source Relocation at Hansbreen, Svalbard. Journal of Geophysical Research (JGR): Earth Surface. ISSN 2169-9003. 131(6). doi: 10.1029/2026JF009237. Fulltekst i vitenarkiv
• Schuler, Thomas Vikhamar; Benestad, Rasmus; Isaksen, Ketil; Kierulf, Halfdan Pascal; Kohler, Jack & Moholdt, Geir [Vis alle 7 forfattere av denne artikkelen] (2025). Svalbard's 2024 record summer: An early view of Arctic glacier meltdown? Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 122(34). doi: 10.1073/pnas.2503806122. Fulltekst i vitenarkiv Vis sammendrag

  A record-breaking melt season affected the Arctic glaciers of Svalbard in summer 2024 by a substantial margin. Across the entire archipelago, glacier melting corresponded to an anomaly of up to four SD and exceeded any previous observation. The pan-Svalbard mass loss in summer 2024 amounts to ~61.7 ± 11.1 Gt and corresponds to 1% of the total ice volume on Svalbard and is comparable to that of the Greenland ice sheet (55 ± 35 Gt), which occupies an area about 50 times larger. Altogether, Svalbard and other glacier regions surrounding the Barents Sea lost 102.1 ± 22.9 Gt of ice in a single year and contributed 0.27 ± 0.06 mm (of which 0.16 mm alone is due to Svalbard) to global sea-level, putting the circum-Barents region among the strongest contributors to global sea-level rise in 2024. Most of the 2024 glacier melt occurred during a 6-wk period of persistent atmospheric circulation pattern causing record-high air temperatures, an event with an extremely low recurrence interval under current climate conditions. However, future climate projections suggest that such temperature levels will become increasingly commonplace by the end of the 21st century, potentially even surpassing those of 2024. Svalbard’s summer of 2024 serves as a forecast for future glacier meltdown in the Arctic, offering a glimpse into conditions 70 y ahead.

• Nanni, Ugo; Bouchayer, Coline Lili Mathy; Åkesson, Henning; Lefeuvre, Pierre-Marie; Mannerfelt, Erik Schytt & Köhler, Andreas [Vis alle 12 forfattere av denne artikkelen] (2025). Observed positive feedback between surface ablation and crevasse formation drives glacier acceleration and potential surge. Nature Communications. 16(1). doi: 10.1038/s41467-025-66349-9. Fulltekst i vitenarkiv Vis sammendrag

  Sudden glacier acceleration and instability, e.g. surges, strongly influence glacier ice loss. However, lack of in-situ observations of the involved processes hampers our ability to understand, quantify and model such a role. We present an analysis of the initiation of a surge (Kongsvegen glacier, Svalbard), focusing on the interplay between climatic and glacier-specific drivers. We integrate two decades of in-situ observations (GNSS, borehole and surface seismometers) with runoff simulations, and remotely sensed surface-elevation changes. We show that initial glacier thinning led to localized acceleration and crevassing. Then, we show that stronger surface melt enabled meltwater to reach the glacier bed. This input promotes high basal water pressure and glacier sliding, and in turn further surface crevassing. Our observations suggest that this positive feedback leads to the expansion of the initially localized instability. Our findings highlight mechanisms that could trigger glacier instabilities under a warming atmosphere beyond the High Arctic.

• Innanen, Satu Karoliina; Hock, Regine; Schmidt, Louise Steffensen; Schuler, Thomas; Covi, Federico & Moholdt, Geir (2025). Witnessing the transition from cold to temperate firn on Austfonna ice cap, Svalbard, through observations and model simulations. Journal of Glaciology. ISSN 0022-1430. 71. doi: 10.1017/jog.2025.10072. Fulltekst i vitenarkiv Vis sammendrag

  Refreezing is a critical component of the mass balance of glaciers in Svalbard, yet the processes and changes under a warming climate are not fully understood. Here, we investigate changes in firn properties of the Austfonna ice cap, Svalbard, using a combination of observations and model simulations. We analyze firn stratigraphy and density from five newly retrieved and 11 previously retrieved firn cores, collected at elevations ranging from 506 m a.s.l. to 791 m a.s.l. between 1958 and 2022. All cores exhibit frequent ice layers that indicate persistent refreezing of meltwater; however, no ice slabs (layers exceeding 1 m) were observed. A 13-year-long firn temperature time series from a site near the summit (773 m a.s.l.) shows that annual water percolation reaches depths of 7 m to over 13 m. A notable transition in the firn thermal regime occurred in 2013, transitioning from cold to temperate conditions above the firn-ice interface despite the seasonal cooling occurring in the upper firn layers. Simulations using the CryoGrid community model from 2009 to 2022 corroborate this thermal shift and suggest the development of a firn aquifer multiple times since 2013, with increasing duration and thickness over time.

• Cao, Wenxue; Aalstad, Kristoffer; Schmidt, Louise Steffensen; Westermann, Sebastian & Schuler, Thomas (2025). Bayesian data assimilation on an Arctic glacier: learning from large ensemble twin experiments. Journal of Glaciology. ISSN 0022-1430. 71, s. 1–17. doi: 10.1017/jog.2025.10101. Fulltekst i vitenarkiv Vis sammendrag

  Numerical modeling is crucial for quantifying the evolution of cryospheric processes. At the same time, uncertainties hamper process understanding and predictive accuracy. Here, we suggest improving glacier surface mass balance simulations for the Kongsvegen glacier in Svalbard through the application of Bayesian data assimilation techniques in a set of large ensemble twin experiments. Noisy synthetic observations of albedo and snow depth, generated using the multilayer CryoGrid community model with a full energy balance, are assimilated using two ensemble-based data assimilation schemes: the particle batch smoother and the ensemble smoother. A comprehensive evaluation exercise demonstrates that the joint assimilation of albedo and snow depth improves the simulation skill by up to 86% relative to the prior in specific glacier regions. The particle batch smoother excels in representing albedo dynamics, while the ensemble smoother is marginally more effective for snow depth under low snowfall conditions in the ablation area. By combining the strengths of both observations, the joint assimilation achieves improved surface mass balance simulations across different glacier zones using either assimilation scheme. This work underscores the potential of ensemble-based data assimilation methods for refining glacier models by offering a robust framework to enhance predictive accuracy and reduce uncertainties in cryospheric simulations. Further advances in glacier data assimilation research with both synthetic and real observations will be critical to better understanding the fate and role of Arctic glaciers in a changing climate.

• Schmidt, Louise Steffensen; Schuler, Thomas; Westermann, Sebastian & Dürig, Tobias (2025). The climatic mass balance of glaciers on Franz Josef Land and Novaya Zemlya, 1991-2022. Journal of Glaciology. ISSN 0022-1430. 71. doi: 10.1017/jog.2024.97. Fulltekst i vitenarkiv Vis sammendrag

  The Arctic is undergoing increased warming compared to the global mean, with major implications for the mass balance of glaciers. Direct observations of mass balance in the Russian Arctic are sparse and remotely sensed volume changes do not provide information about climatic drivers. Here, we present simulations of the climatic mass balance and meltwater runoff from glaciers in Franz Josef Land and Novaya Zemlya from 1991 to 2022. Based on simulations of glacier climatic mass balance over the period 1991–2022, we present a first detailed view of mass balance evolution in Franz Josef Land and Novaya Zemlya. The simulations are conducted at a 2.5 km resolution using the CryoGrid model forced by the Copernicus Arctic Regional ReAnalysis (CARRA) product. Over the 30 year simulation period, the climatic mass balance of both Franz Josef Land (0.21m w.e. a−1) and Novaya Zemlya (0.07 m w.e. a−1) is positive on average without a significant trend in annual climatic mass balance. There is still a tendency towards more frequent high-melt years after 2010 and the associated glacier runoff has intensified with record melt years occurring during the model period.

• Bouchayer, Coline Lili Mathy; Nanni, Ugo; Lefeuvre, Pierre-Marie; Hulth, John; Schmidt, Louise Steffensen & Kohler, Jack [Vis alle 8 forfattere av denne artikkelen] (2024). Multi-scale variations of hydro-mechanical conditions at the base of the surge-type glacier Kongsvegen, Svalbard. The Cryosphere. ISSN 1994-0416. 18(6), s. 2939–2968. doi: 10.5194/tc-18-2939-2024. Fulltekst i vitenarkiv Vis sammendrag

  The flow of glaciers is largely controlled by changes at the ice–bed interface, where basal slip and sediment deformation drive basal glacier motion. Determining subglacial conditions and their responses to hydraulic forcing remains challenging due to the difficulty of accessing the glacier bed. Here, we monitor the interplay between surface runoff and hydro-mechanical conditions at the base of the Kongsvegen glacier in Svalbard. From July 2021 to August 2022, we measured both subglacial water pressure and till strength. Additionally, we derived median values of subglacial hydraulic gradient and radius of channelized subglacial drainage system from seismic power, recorded at the glacier surface. To characterize the variations in the subglacial conditions caused by changes in surface runoff, we investigate the variations of the following hydro-mechanical properties: measured water pressure, measured sediment ploughing forces, and derived hydraulic gradient and radius, over seasonal, multi-day, and diurnal time

• Foss, Øyvind; Maton, Joséphine; Moholdt, Geir; Schmidt, Louise Steffensen; Sutherland, David A. & Fer, Ilker [Vis alle 9 forfattere av denne artikkelen] (2024). Ocean warming drives immediate mass loss from calving glaciers in the high Arctic. Nature Communications. 15(1). doi: 10.1038/s41467-024-54825-7. Fulltekst i vitenarkiv Vis sammendrag

  Glaciers in the Arctic have lost considerable mass during the last two decades. About a third of the glaciers by area drains into the ocean, yet the mechanisms and drivers governing mass loss at glacier calving fronts are poorly con- strained in part due to few long-term glacier-ocean observations. Here, we combine a detailed satellite-based record of calving front ablation for Austfonna, the largest ice cap on Svalbard, with in-situ ocean records from an offshore mooring and modelled freshwater runoff for the period 2018-2022. We show that submarine melting and calving occur almost exclusively in autumn for all types of outlet glaciers, even for the surging and fast-flowing glacier Storisstraumen. Ocean temperature controls the observed frontal ablation, whereas subglacial runoff of surface meltwater appears to have little direct impact on the total ablation. The seasonal warming of the offshore waters varies both in magnitude, depth and timing, suggesting a complex interplay between inflowing Atlantic-influenced water at depth and seasonally warmed surface water in the Barents Sea. The immediate response of frontal ablation to seasonal ocean warming suggests that marine-terminating glaciers in high Arctic regions exposed to Atlantification are prone to rapid changes that should be accounted for in future glacier projections.

• Spolaor, Andrea; Scoto, Federico; Larose, Catherine; Barbaro, Elena; Burgay, Francois & Björkman, Mats Peter [Vis alle 22 forfattere av denne artikkelen] (2024). Climate change is rapidly deteriorating the climatic signal in Svalbard glaciers. The Cryosphere. ISSN 1994-0416. 18(1), s. 307–320. doi: 10.5194/tc-18-307-2024. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen; Schuler, Thomas; Thomas, Erin E. & Westermann, Sebastian (2023). Meltwater runoff and glacier mass balance in the high Arctic: 1991-2022 simulations for Svalbard. The Cryosphere. ISSN 1994-0416. 17(7), s. 2941–2963. doi: 10.5194/tc-17-2941-2023. Fulltekst i vitenarkiv Vis sammendrag

  Abstract. The Arctic is undergoing increased warming compared to the global mean, which has major implications for freshwater runoff into the oceans from seasonal snow and glaciers. Here, we present high-resolution (2.5 km) simulations of glacier mass balance, runoff, and snow conditions on Svalbard from 1991–2022, one of the fastest warming regions in the world. The simulations are created using the CryoGrid community model forced by Copernicus Arctic Regional ReAnalysis (CARRA) (1991–2021) and AROME-ARCTIC forecasts (2016–2022). Updates to the water percolation and runoff schemes are implemented in the CryoGrid model for the simulations. In situ observations available for Svalbard, including automatic weather station data, stake measurements, and discharge observations, are used to carefully evaluate the quality of the simulations and model forcing. We find a slightly negative climatic mass balance (CMB) over the simulation period of −0.08 mw.e.yr-1 but with no statistically significant trend. The most negative annual CMB is found for Nordenskiöldland (−0.73 mw.e.yr-1), with a significant negative trend of −0.27 mw.e. per decade for the region. Although there is no trend in the annual CMB, we do find a significant increasing trend in the runoff from glaciers of 0.14 mw.e. per decade. The average runoff was found to be 0.8 mw.e.yr-1. We also find a significant negative trend in the refreezing of −0.13 mw.e. per decade. Using AROME-ARCTIC forcing, we find that 2021/22 has the most negative CMB and highest runoff over the 1991–2022 simulation period investigated in this study. We find the simulated climatic mass balance and runoff using CARRA and AROME-ARCTIC forcing are similar and differ by only 0.1 mw.e.yr-1 in climatic mass balance and by 0.2 mw.e.yr-1 in glacier runoff when averaged over all of Svalbard. There is, however, a clear difference over Nordenskiöldland, where AROME-ARCTIC simulates significantly higher mass balance and significantly lower runoff. This indicates that AROME-ARCTIC may provide similar high-quality predictions of the total mass balance of Svalbard as CARRA, but regional uncertainties should be taken into consideration. The simulations produced for this study are made publicly available at a daily and monthly resolution, and these high-resolution simulations may be re-used in a wide range of applications including studies on glacial runoff, ocean currents, and ecosystems.

• Dürig, Tobias; Schmidt, Louise Steffensen & Dioguardi, Fabio (2023). Optimizing mass eruption rate estimates by combining simple plume models. Frontiers in Earth Science. 11. doi: 10.3389/feart.2023.1250686. Fulltekst i vitenarkiv Vis sammendrag

  Tephra injected into the atmosphere by volcanic ash plumes poses one of the key hazards in explosive eruptions. Forecasting the atmospheric dispersal of volcanic ash requires good knowledge of the current eruption source parameters, in particular of the mass eruption rate ( MER ), which quantifies the mass flow rate of gas and tephra at the vent. Since this parameter cannot be directly measured in real-time, monitoring efforts aim to assess the MER indirectly, for example, by applying plume models that link the (relatively easily detectable) plume height with the mass flux at the vent. By comparing the model estimates with independently acquired fallout measurements from the 130 eruptions listed in the Independent Volcanic Eruption Source Parameter Archive (Aubry et al., J. Volcanol. Geotherm. Res., 2021, 417), we tested the success rates of six 0D plume models along with four different modelling approaches with the aim to optimize MER prediction. According to our findings, instead of simply relying on the application of one plume model for all situations, the accuracy of MER forecast can be increased by mixing the plume models via model weight factors when these factors are appropriately selected. The optimal choice of model weight factors depends on the availability and type of volcanological and meteorological information for the eruption monitored. A decision tree is presented that assists the reader in finding the optimal modelling strategy to ascertain highest MER forecast accuracy.

• Dürig, Tobias; Gudmundsson, Magnus T.; Dioguardi, Fabio & Schmidt, Louise Steffensen (2023). Quantifying the Effect of Wind on Volcanic Plumes: Implications for Plume Modeling. Journal of Geophysical Research (JGR): Atmospheres. ISSN 2169-897X. 128(2). doi: 10.1029/2022JD037781. Fulltekst i vitenarkiv
• Westermann, Sebastian; Ingeman-Nielsen, Thomas; Scheer, Johanna; Aalstad, Kristoffer; Aga, Juditha & Chaudhary, Nitin [Vis alle 24 forfattere av denne artikkelen] (2023). The CryoGrid community model (version 1.0) - a multi-physics toolbox for climate-driven simulations in the terrestrial cryosphere. Geoscientific Model Development. ISSN 1991-959X. 16(9), s. 2607–2647. doi: 10.5194/gmd-16-2607-2023. Fulltekst i vitenarkiv Vis sammendrag

  The CryoGrid community model is a flexible toolbox for simulating the ground thermal regime and the ice–water balance for permafrost and glaciers, extending a well-established suite of permafrost models (CryoGrid 1, 2, and 3). The CryoGrid community model can accommodate a wide variety of application scenarios, which is achieved by fully modular structures through object-oriented programming. Different model components, characterized by their process representations and parameterizations, are realized as classes (i.e., objects) in CryoGrid. Standardized communication protocols between these classes ensure that they can be stacked vertically. For example, the CryoGrid community model features several classes with different complexity for the seasonal snow cover, which can be flexibly combined with a range of classes representing subsurface materials, each with their own set of process representations (e.g., soil with and without water balance, glacier ice). We present the CryoGrid architecture as well as the model physics and defining equations for the different model classes, focusing on one-dimensional model configurations which can also interact with external heat and water reservoirs. We illustrate the wide variety of simulation capabilities for a site on Svalbard, with point-scale permafrost simulations using, e.g., different soil freezing characteristics, drainage regimes, and snow representations, as well as simulations for glacier mass balance and a shallow water body. The CryoGrid community model is not intended as a static model framework but aims to provide developers with a flexible platform for efficient model development. In this study, we document both basic and advanced model functionalities to provide a baseline for the future development of novel cryosphere models.

• Dürig, Tobias; Gudmundsson, Magnús T.; Ágústsdóttir, Thorbjörg; Högnadóttir, Thórdís & Schmidt, Louise Steffensen (2022). The effect of wind and plume height reconstruction methods on the accuracy of simple plume models — a second look at the 2010 Eyjafjallajökull eruption. Bulletin of Volcanology. ISSN 0258-8900. 84. doi: 10.1007/s00445-022-01541-z. Fulltekst i vitenarkiv
• Yue, Chao; Schmidt, Louise Steffensen; Zhao, Liyun; Wolovick, Michae & Moore, John C. (2021). Vatnajökull Mass Loss Under Solar Geoengineering Due to the North Atlantic Meridional Overturning Circulation. Earth's Future. 9(9). doi: 10.1029/2021EF002052. Fulltekst i vitenarkiv
• Dürig, Tobias; White, James D.L.; Murch, AP; Zimanowski, Bernd; Buttner, R & Mele, D. [Vis alle 10 forfattere av denne artikkelen] (2020). Deep-sea eruptions boosted by induced fuel–coolant explosions. Nature Geoscience. ISSN 1752-0894. 13, s. 498–503. doi: 10.1038/s41561-020-0603-4. Fulltekst i vitenarkiv Vis sammendrag

  The majority of Earth’s volcanic eruptions occur beneath the sea, but the limited number of direct observations and samples limits our understanding of these unseen events. Subaerial eruptions lend some insight, but direct extrapolation from the subaerial to the deep sea is precluded by the great differences in pressure, thermal conditions, density and rheology, and the interplay among them. Here we present laboratory fragmentation experiments that mimic deep-sea explosive eruptions and compare our laboratory observations with those from the kilometre-deep submarine eruption of Havre Volcano, Kermadec Arc, New Zealand, in 2012. We find that the Havre eruption involved explosive fragmentation of magma by a pressure-insensitive interaction between cool water and hot magma, termed an induced fuel–coolant interaction. The laboratory experiments show that this water–magma interaction is initiated by the formation of cracks in cooling magma into which the water coolant can infiltrate, driving explosive fragmentation. Explosive submarine eruptions have previously been considered unlikely because stabilization of a vapour film at the magma–water contact was thought to be a key requirement but is suppressed at depths exceeding 100 m. However, here we demonstrate that these induced fuel–coolant interactions between magma and water can occur in a range of wet environments regardless of pressure, from the subaerial to the deep sea, and may operate on different planets, as well as apply to materials other than magma and water.

• Adalgeirsdottir, Gudfinna; Magnusson, Eyjólfur; Pálsson, Finnur; Thorsteinsson, Thorsteinn; Belart, Joaquin M. C. & Johannesson, Tomas [Vis alle 14 forfattere av denne artikkelen] (2020). Glacier changes in Iceland from ~1890 to 2019. Frontiers in Earth Sciences. ISSN 1863-4621. 8, s. 1–15. doi: 10.3389/feart.2020.523646. Fulltekst i vitenarkiv Vis sammendrag

  The volume of glaciers in Iceland (∼3,400 km3 in 2019) corresponds to about 9 mm of potential global sea level rise. In this study, observations from 98.7% of glacier covered areas in Iceland (in 2019) are used to construct a record of mass change of Icelandic glaciers since the end of the 19th century i.e. the end of the Little Ice Age (LIA) in Iceland. Glaciological (in situ) mass-balance measurements have been conducted on Vatnajökull, Langjökull, and Hofsjökull since the glaciological years 1991/92, 1996/97, and 1987/88, respectively. Geodetic mass balance for multiple glaciers and many periods has been estimated from reconstructed surface maps, published maps, aerial photographs, declassified spy satellite images, modern satellite stereo imagery, and airborne lidar. To estimate the maximum glacier volume at the end of the LIA, a volume–area scaling method is used based on the observed area and volume from the three largest ice caps (over 90% of total ice mass) at 5–7 different times each, in total 19 points. The combined record shows a total mass change of −540 ± 130 Gt (−4.2 ± 1.0 Gt a−1 on average) during the study period (1890/91 to 2018/19). This mass loss corresponds to 1.50 ± 0.36 mm sea level equivalent or 16 ± 4% of mass stored in Icelandic glaciers around 1890. Almost half of the total mass change occurred in 1994/95 to 2018/19, or −240 ± 20 Gt (−9.6 ± 0.8 Gt a−1 on average), with most rapid loss in 1994/95 to 2009/10 (mass change rate −11.6 ± 0.8 Gt a−1). During the relatively warm period 1930/31–1949/50, mass loss rates were probably close to those observed since 1994, and in the colder period 1980/81–1993/94, the glaciers gained mass at a rate of 1.5 ± 1.0 Gt a−1. For other periods of this study, the glaciers were either close to equilibrium or experienced mild loss rates. For the periods of AR6 IPCC, the mass change rates are −3.1 ± 1.1 Gt a−1 for 1900/01–1989/90, −4.3 ± 1.0 Gt a−1 for 1970/71–2017/18, −8.3 ± 0.8 Gt a−1 for 1992/93–2017/18, and −7.6 ± 0.8 Gt a−1 for 2005/06–2017/18.

• Schmidt, Louise Steffensen; Adalgeirsdottir, Gudfinna; Pálsson, Finnur; Langen, Peter L.; Guđmundsson, Sverrir & Björnsson, Helgi (2020). Dynamic simulations of Vatnajökull ice cap from 1980 to 2300. Journal of Glaciology. ISSN 0022-1430. 66(255). doi: 10.1017/jog.2019.90. Fulltekst i vitenarkiv
• Dürig, Tobias; Schmidt, Louise Steffensen; White, James D.L. & Bowman, M. H. (2020). DendroScan: an open source tool to conduct comparative statistical tests and dendrogrammatic analyses on particle morphometry. Scientific Reports. 10. doi: 10.1038/s41598-020-78698-0. Fulltekst i vitenarkiv Vis sammendrag

  Abstract Quantitative shape analysis of juvenile pyroclasts is applied in volcanology to reconstruct the dynamics and styles of eruptions, and to explore the details of tephra transport, dispersal, and emplacement. Morphometric analyses often include comparison of multiple data sets with a set of dimensionless shape parameters. Here we present “DendroScan”, an open source Matlab program that provides the user with all the multivariate statistical methods needed to produce such morphometric comparisons. Serving as a statistical “toolbox”, DendroScan conducts Levene-, t-, and equivalence tests, presenting the results in ad hoc interpretable graphs. Furthermore, it is designed to conduct dendrogrammatic analyses of particle morphometry, a recently developed approach for the inter-comparison of multiple morphometric data sets. DendroScan produces tree diagrams, in which the analysed samples are sorted according to their morphometric dissimilarity, allowing the user to identify, e.g., samples that are statistically equivalent. To demonstrate DendroScan’s potential, ten experimental samples are compared with volcanic ash samples generated by the Havre 2012 deep-sea eruption in the Kermadec arc (New Zealand). We show how, using DendroScan-based results, information on the eruptive mechanism can be inferred, and how the cooling history of the experimental melt is reflected in the dissimilarity of thermally granulated fragments.

• Schmidt, Louise Steffensen; Hvidberg, Christine; Kim, Jungrack & Karlsson, Nanna B (2019). Non-linear flow modelling of a Martian Lobate Debris Apron. Journal of Glaciology. ISSN 0022-1430. 65(254), s. 889–899. doi: 10.1017/jog.2019.54. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen; Langen, Peter L.; Adalgeirsdottir, Gudfinna; Pálsson, Finnur; Guðmundsson, Sverrir & Gunnarsson, Andri (2018). Sensitivity of glacier runoff to winter snow thickness investigated for Vatnajökull ice cap, Iceland, using numerical models and observations. Atmosphere. 9(11). doi: 10.3390/atmos9110450. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen; Aðalgeirsdóttir, Guðfinna; Guðmundsson, Sverrir; Langen, Peter L.; Pálsson, Finnur & Mottram, Ruth [Vis alle 8 forfattere av denne artikkelen] (2017). The importance of accurate glacier albedo for estimates of surface mass balance on Vatnajökull. The Cryosphere. ISSN 1994-0416. 11(4), s. 1665–1684. doi: 10.5194/tc-11-1665-2017. Fulltekst i vitenarkiv
• Gascoin, Simon; Guðmundsson, Sverrir; Adalgeirsdottir, Gudfinna; Pálsson, Finnur; Schmidt, Louise Steffensen & Berthier, Etienne [Vis alle 7 forfattere av denne artikkelen] (2017). Evaluation of MODIS albedo product over ice caps in Iceland and impact of volcanic eruptions on their albedo. Remote Sensing. 5(9). doi: 10.3390/rs9050399. Fulltekst i vitenarkiv
• Karlsson, Nanna B.; Schmidt, Louise Steffensen & Hvidberg, Christine (2015). Volume of Martian midlatitude glaciers from radar observations and ice flow modeling. Geophysical Research Letters. ISSN 0094-8276. 42(8), s. 2627–2633. doi: 10.1002/2015GL063219. Fulltekst i vitenarkiv

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• Schuler, Thomas; Nanni, Ugo; Bouchayer, Coline Lili Mathy; Åkesson, Henning; Lefeuvre, Pierre-Marie & Mannerfelt, Erik Schytt [Vis alle 9 forfattere av denne artikkelen] (2024). Observed weakening of glacier ice-bed interface caused by climatic and hydro-mechanical feedbacks: towards glacier-wide acceleration? Fulltekst i vitenarkiv Vis sammendrag

  Stronger and more widespread surface melt may alter the flow of glaciers and ice sheets and trigger instability. However, observational deficiencies hamper our ability to better understand and thus predict such responses. We deployed surface and borehole seismometers along the centerline of a High Arctic glacier in Svalbard. The records span over six years and are analyzed in relation to the measured increase of surface velocity. We complement our seismic analysis (icequakes and seismic noise) with long-term measurements of glacier-surface velocity, surface-elevation changes, and runoff modeling. Since 2000, we observe glacier thinning and steepening, coinciding with acceleration of up to 1000%. In response, new crevasses have opened and provide access pathways for surface melt water to the base of the glacier, affecting the ice-bed coupling. This mechanism represents a positive hydro-mechanical feedback that fuels further acceleration and crevassing. This feedback may have wider implications for triggering of glacier-wide instabilities, increasing short-term sea-level rise and local hazards. Beyond the Arctic, we suggest that, under a warming atmosphere, glaciers may transition from stable to unstable flow through such a mechanism.

• Alexander, Andreas; Piermattei, Livia; Assmy, Philipp Kurt Wolf; Popp, Andrea; Valiente, Nicolás & Tallentire, Guy [Vis alle 19 forfattere av denne artikkelen] (2023). The impact of subglacial drainage system evolution and glacier lake outburst on Arctic fjord macronutrient dynamics: Kongsfjorden, Svalbard. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen; Schuler, Thomas Vikhamar & Westermann, Sebastian (2023). Towards an interdisciplinary information platform displaying the state of the cryosphere on Svalbard. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen; Schuler, Thomas; Westermann, Sebastian & Thomas, Erin E. (2022). Climatic mass balance simulations of glaciers in the Russian Arctic (Novaya Zemlya and Franz Josef Land), 1991-2021. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen; Thomas, Erin E.; Westermann, Sebastian & Schuler, Thomas (2022). Climatic mass balance simulations of glaciers in the Russian Arctic (Novaya Zemlya and Franz Josef Land), 1991-2021. Fulltekst i vitenarkiv
• Lundesgaard, Øyvind; Moholdt, Geir; Maton, Joséphine; Sutherland, D.A. & Schmidt, Louise Steffensen (2022). Autumn Inflow of Atlantic Water Drives Seasonal Retreat of Glacier Fronts on the Northern Barents Sea Margin of Svalbard. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen; Schuler, Thomas Vikhamar & Westermann, Sebastian (2021). Freshwater runoff to the Barents sea region, 1998-present. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen; Schuler, Thomas Vikhamar; Thomas, Erin E. & Westermann, Sebastian (2021). Simulations of mass balance and runoff from Svalbard, 1998-present. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen & Schuler, Thomas Vikhamar (2021). Freshwater runoff from glaciers and seasonal snow to the Barents sea region, 1998-present. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen & Schuler, Thomas Vikhamar (2021). Freshwater runoff from glaciers and seasonal snow to the Barents sea region. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen (2021). Glaciers and climate change. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen (2020). Freshwater runoff from glaciers to the Barent sea region. Fulltekst i vitenarkiv
• Schmidt, Louise Steffensen (2020). Variability in glacier meltwater runoff to the Barents Sea. Fulltekst i vitenarkiv
• Tjoflot, Gunn Kristin & Schmidt, Louise Steffensen (2020). Avrenning av smeltevann fra landbaserte isbreer til Barentshavet. [Internet]. https://arvenetternansen.com/. Fulltekst i vitenarkiv Vis sammendrag

  Intervju med Louise Steffensen Schmidt (Arven etter Nansen), postdoc, Institutt for geofag, Universitetet i Oslo. Nylig presenterte hun sin forskning i foredraget: Variability in glacier meltwater runoff to the Barents Sea, på Arven etter Nansens 3. årsmøte, 10-12 november 2020.

• Schmidt, Louise Steffensen (2022). CryoGrid simulations of Svalbard mass balance, refreezing and runoff, 1991-2022. Norwegian Meteorological Institute. Fulltekst i vitenarkiv

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