Harry Zekollari

• Associate Professor
• Research Professor at Vrije Universiteit Brussel

Glaciers play a crucial role in the Earth System: they are important water suppliers to lower‐lying areas during hot and dry periods, and they are major contributors to the observed present‐day sea‐level rise. Glaciers can also act as a source of natural hazards and have a major touristic value. Given their societal importance, there is large scien...

More than 60% of meteorite finds on Earth originate from Antarctica. Using a data-driven analysis that identifies meteorite-rich sites in Antarctica, we show climate warming causes many extraterrestrial rocks to be lost from the surface by melting into the ice sheet. At present, approximately 5,000 meteorites become inaccessible per year (versus ~1...

Glaciers are indicators of ongoing anthropogenic climate change ¹ . Their melting leads to increased local geohazards ² , and impacts marine ³ and terrestrial 4,5 ecosystems, regional freshwater resources ⁶ , and both global water and energy cycles 7,8 . Together with the Greenland and Antarctic ice sheets, glaciers are essential drivers of present...

Projecting the global evolution of glaciers is crucial to quantify future sea-level rise and changes in glacier-fed rivers. Recent intercomparison efforts have shown that a large part of the uncertainties in the projected glacier evolution is driven by the glacier model itself and by the data used for initial conditions and calibration. Here, we qu...

Glacier retreat presents significant environmental and social challenges. Understanding the local impacts of climatic drivers on glacier evolution is crucial, with mass balance being a central concept. This study introduces miniML-MB, a new minimal machine-learning model designed to estimate annual point surface mass balance (PMB) for very small da...

It is essential to improve our understanding of mountain glaciers and their effects on sea level, ecosystems, and freshwater resources in a changing climate. To this end, we implemented a framework for three-dimensional, high-resolution, regional-scale glacier simulations in the Community Ice Sheet Model (CISM v2.2), using higher-order ice-flow dyn...

Glaciers adapt slowly to changing climatic conditions, resulting in long-term changes in their mass with implications for sea level rise and water supply, even if the climate were to stabilize. Using eight glacier evolution models, we simulate global glacier evolution over multi-centennial timescales, allowing glaciers to equilibrate with climate u...

The more than 200,000 glaciers outside the ice sheets play a crucial role in our society by influencing sea-level rise, water resource management, natural hazards, biodiversity, and tourism. However, only a fraction of these glaciers benefit from consistent and detailed in-situ observations that allow for assessing their status and changes over tim...

Glacier retreat presents significant environmental and social challenges. Understanding the local impacts of climatic drivers on glacier evolution is crucial, with mass balance being a central concept. This study introduces miniML-MB, a new minimal machine learning model designed to estimate annual point surface mass balance (PMB) for very small da...

Hydrological models play a vital role in projecting future changes in streamflow. Despite the strong awareness of non-stationarity in hydrological system characteristics, model parameters are typically assumed to be stationary and derived through calibration on past conditions. Integrating the dynamics of system change in hydrological models remain...

Within scenario-based research of social-ecological systems, there has been a growing recognition of the importance of normative scenarios that define positive outcomes for both nature and society. While several frameworks exist to guide the co-creation of normative scenario narratives, examples of operationalizing these narratives in quantitative...

Projecting the global evolution of glaciers is crucial to quantify future sea-level rise and changes in glacier-fed rivers. Recent intercomparison efforts have shown that a large part of the uncertainties in the projected glacier evolution is driven by the glacier model itself and by the data used for initial conditions and calibration. Here, we qu...

The latest generation of climate models provide temperature and precipitation data at (sub)daily time scales. This data allows investigating how the temporal resolution affects projections about glacier volume, especially since glacier models typically rely on monthly forcing data. But does this really make a difference? Findings from a pioneering...

Plain Language Summary While most of the continent of Antarctica is covered by snow, in some areas, ice is exposed at the surface, with a typical blue color. At lower elevations, blue ice enhances melt‐water production, which is important for studying the future of the ice sheet. Moreover, scientific teams frequently visit blue ice areas (BIAs) as...

We provide a comprehensive overview of a reconnaissance expedition aimed at identifying new possible meteorite stranding zones in the surrounding of the Belgian Princess Elisabeth Antarctica (PEA) station in the Sør Rondane Mountains during the BELARE 2022-2023 field season. The team was composed of four scientists and one field guide. Several area...

Modeling the short‐term (<50 years) evolution of glaciers is difficult because of issues related to model initialization and data assimilation. However, this timescale is critical, particularly for water resources, natural hazards, and ecology. Using a unique record of satellite remote‐sensing data, combined with a novel optimisation and surface‐fo...

More than 13% of the area of the Caucasus glaciers is covered by debris affecting glacier mass balance. Using the Caucasus as example, we introduce a new model configuration that incorporates a physically-based subroutine for the evolution of supraglacial debris into the Global Glacier Evolution Model (GloGEMflow), enabling its application at a reg...

Here, we present a compilation of 95 ice temperature profiles from 85 boreholes from the Greenland ice sheet and peripheral ice caps, as well as local ice caps in the Canadian Arctic. Profiles from only 31 boreholes (36 %) were previously available in open-access data repositories. The remaining 54 borehole profiles (64 %) are being made digitally...

Glaciers in the Tien Shan are vital for freshwater supply, emphasising the importance of modelling their future evolution. While detailed 3D models are suitable for well-studied glaciers, regional and global assessments rely on simplified approaches. However, their accuracy remains understudied. Here, we compare the evolution of six glaciers in the...

Modelling the short-term (<50 years) evolution of glaciers is difficult because of issues related to model initialisation and data assimilation. However, this timescale is critical, particularly for water resources, natural hazards, and ecology. Using a unique record of satellite remote-sensing data, combined with a novel optimisation and SMB-calcu...

Global hydrological models have become a valuable tool for a range of global impact studies related to water resources. However, glacier parameterization is often simplistic or non-existent in global hydrological models. By contrast, global glacier models do represent complex glacier dynamics and glacier evolution, and as such, they hold the promis...

Here, we present a compilation of 85 ice temperature profiles from 79 boreholes from the Greenland Ice Sheet and peripheral ice caps, as well as local ice caps in the Canadian Arctic. Only 25 profiles (32 %) were previously available in open-access data repositories. The remaining 54 profiles (68 %) are being made digitally available here for the f...

Glaciers around the world are shrinking rapidly and will continue to do so in the next decades. Anticipating the consequences resulting from such glacier changes is key to design and implement adequate mitigation measures. Here, we focus on the future evolution of potential ice-dammed and supraglacial lakes in High Mountain Asia, as such lakes are...

Global hydrological models have become a valuable tool for a range of global impact studies related to water resources. However, glacier parameterization is often simplistic or non-existent in global hydrological models. By contrast, global glacier models do represent complex glacier dynamics and glacier evolution, and as such hold the promise of b...

Currently, about 12 %–13 % of High Mountain Asia’s glacier area is debris-covered, which alters its surface mass balance. However, in regional-scale modelling approaches, debris-covered glaciers are typically treated as clean-ice glaciers, leading to a bias when modelling their future evolution. Here, we present a new approach for modelling debris...

River ecosystems are highly sensitive to climate change and projected future increase in air temperature is expected to increase the stress for these ecosystems. Rivers are also an important socio-economic factor impacting, amongst others, agriculture, tourism, electricity production, and drinking water supply and quality. In addition to changes in...

Meteorites provide a unique view into the origin and evolution of the Solar System. Antarctica is the most productive region for recovering meteorites, where these extraterrestrial rocks concentrate at meteorite stranding zones. To date, meteorite-bearing blue ice areas are mostly identified by serendipity and through costly reconnaissance missions...

Glaciers and ice caps are experiencing strong mass losses worldwide, challenging water availability, hydropower generation, and ecosystems. Here, we perform the first-ever glacier evolution projections based on deep learning by modelling the 21st century glacier evolution in the French Alps. By the end of the century, we predict a glacier volume lo...

The surface mass balance (SMB) of a glacier provides the link between the glacier and the local climate. For this reason, it is intensively studied and monitored. However, major efforts are required to determine the point SMB at a sufficient number of locations to capture the heterogeneity of the SMB pattern. Furthermore, because of the time-consum...

Currently, about 12–13 % of High Mountain Asia's glacier area is debris-covered, altering its surface mass balance. However, in regional-scale modelling approaches, debris-covered glaciers are typically treated as clean-ice glaciers, leading to a potential bias when modelling their future evolution. Here, we present a new approach for modelling deb...

Hydrological regimes of alpine catchments are expected to be strongly affected by climate change, mostly due to their dependence on snow and ice dynamics. While seasonal changes have been studied extensively, studies on changes in the timing and magnitude of annual extremes remain rare. This study investigates the effects of climate change on runof...

With the Paris Agreement, the urgency of limiting ongoing anthropogenic climate change has been recognised. More recent discussions have focused on the difference of limiting the increase in global average temperatures below 1.0, 1.5, or 2.0 ∘C compared to preindustrial levels. Here, we assess the impacts that such different scenarios would have on...

The land ice contribution to global mean sea level rise has not yet been predicted¹ using ice sheet and glacier models for the latest set of socio-economic scenarios, nor using coordinated exploration of uncertainties arising from the various computer models involved. Two recent international projects generated a large suite of projections using mu...

Rivers are ecosystems highly sensitive to climate change and projected future increase in air temperature is expected to increase the stress for these ecosystems. Rivers are also an important socio-economical factor. In addition to changes in water availability, climate change will impact the temperature of rivers. This study presents a detailed an...

Due to climate change, worldwide glaciers are rapidly declining. The trend will continue into the future, with consequences for sea level, water availability and tourism. Here, we assess the future evolution of all glaciers in Scandinavia and Iceland until 2100 using the coupled surface mass-balance ice-flow model GloGEMflow. The model is initialis...

Hydrological regimes of alpine catchments are expected to be strongly affected by climate change mostly due to their dependence on snow and ice dynamics. While seasonal changes have been studied extensively, studies on changes in the timing and magnitude of annual extremes remain rare. This study investigates the effects of climate change on runoff...

With the Paris Agreement, the urgency of limiting ongoing anthropogenic climate change has been recognized. More recent discussions have focused on the difference of limiting the increase in global average temperatures below 1.0, 1.5, or 2.0 °C compared to pre-industrial levels. Here, we assess the impacts that such different scenarios would have o...

Abstract Glacier mass loss is recognized as a major contributor to current sea level rise. However, large uncertainties remain in projections of glacier mass loss on global and regional scales. We present an ensemble of 288 glacier mass and area change projections for the 21st century based on 11 glacier models using up to 10 general circulation mo...

The Mont-Blanc massif, being iconic with its large glaciers and peaks of over 4,000 m, will experience a sharp increase in summer temperatures during the twenty-frst century. By 2100, the impact of climate change on the cryosphere and hydrosphere in the Alps is expected to lead to a decrease in annual river discharge. In this work, we modelled the...

Glaciers in the European Alps rapidly lose mass to adapt to changes in climate conditions. Here, we investigate the relationship and lag between climate forcing and geometric glacier response with a regional glacier evolution model accounting for ice dynamics. The volume loss occurring as a result of the glacier‐climate imbalance increased over the...

Climate change is causing widespread glacier retreat1, and much attention is devoted to negative impacts such as diminishing water resources2, shifts in runoff seasonality3, and increases in cryosphere-related hazards4. Here we focus on a different aspect, and explore the water-storage and hydropower potential of areas that are expected to become i...

Extreme low and high flows can have negative economic, social, and ecological effects and are expected to become more severe in many regions due to climate change. Besides low and high flows, the whole flow regime, i.e., annual hydrograph comprised of monthly mean flows, is subject to changes. Knowledge on future changes in flow regimes is importan...

Glaciers in the European Alps play an important role in the hydrological cycle, act as a source for hydroelectricity and have a large touristic importance. The future evolution of these glaciers is driven by surface mass balance and ice flow processes, of which the latter is to date not included explicitly in regional glacier projections for the Al...

Extreme low and high flows can have negative economical, societal, and ecological effects and are expected to become more severe in many regions due to climate change. Besides low and high flows, the whole flow regime is subject to changes. Knowledge on future changes in flow regimes is important since regimes contain information on both extremes a...

Antarctic blue ice zones, the most productive locations for meteorite recovery on Earth, contain old ice that is easily accessible and available in large quantities. However, the mechanisms behind these meteorite traps remain a topic of ongoing debate. Here, we propose an interdisciplinary approach to improve our understanding of a meteorite trap i...

In Alpine regions, future changes in glacier and snow cover are expected to change runoff regimes towards higher winter but lower summer discharge. The low summer discharge will coincide with the highest water demand for irrigation, and local and regional water shortages are expected to become more likely. One possible measure to adapt to these cha...

Glaciers in the European Alps play an important role in the hydrological cycle, act as a source for hydroelectricity and have a large touristic importance. The future evolution of these glaciers is driven by surface mass balance and ice flow processes, which the latter is to date not included in regional glacier projections for the Alps. Here, we m...

In this study we analyse a 15-year long time series of surface mass-balance (SMB) measurements performed between 2001 and 2016 in the ablation zone of the Morteratsch glacier complex (Engadine, Switzerland). For a better understanding of the SMB variability and its causes, multiple linear regressions analyses are performed with temperature and prec...

TopoZeko is a MATLAB function for plotting a variety of natural environments with a pronounced topography, such as glaciers, volcanoes and lakes in mountainous regions. This function extends existing MATLAB plotting routines and allows for high-quality 3-D landscape visualization, with a single color defining a featured surface type or with a color...

In this study the Holocene evolution of Hans Tausen Iskappe (Peary Land, North Greenland) is investigated. Constraints on the ice cap evolution are combined with climatic records in a numerical ice flow e surface mass balance (SMB) model to better understand the palaeoenvironmental and climatic evolution of this region. Our simulations suggest that...

Corrigendum to tc-11-805-2017

In this study the dynamics and sensitivity of Hans Tausen Iskappe (western Peary Land, Greenland) to climatic forcing is investigated with a coupled ice flow–mass balance model. The surface mass balance (SMB) is calculated from a precipitation field obtained from the Regional Atmospheric Climate Model (RACMO2.3), while runoff is calculated from a p...

In this study the dynamics and sensitivity to climatic forcing of Hans Tausen Iskappe (western Peary Land, Greenland) are investigated with a coupled ice flow – mass balance model. The surface mass balance is calculated from a Positive Degree-Day runoff/retention model, for which the input parameters are derived from field observations. The precipi...

Geophysical Research Abstracts Vol. 18, EGU2016-3062, 2016

A two-dimensional surface mass-balance model is coupled to a three-dimensional higher-order ice flow model to assess the imbalance between climate and glacier geometry for the Morteratsch (Engadine, Switzerland) glacier complex. The climate–geometry imbalance has never been larger than at present, indicating that the temperature increase is faster...

This paper reports on a joint expedition (JARE-54 and BELARE 2012-2013) that conducted a search for meteorites on the Nansen Ice Field, Antarctica, in an area south of the Sør Rondane Mountains (72°30′⊖73°S, 23°⊖25°E; elevation 2900⊖3000 m). The expedition took place over a period of 39 days during the austral summer, between 26 December 2012 and 2...

We use a 3-D higher-order glacier flow model for Vadret da Morteratsch, Engadin, Switzerland, to simulate its strong retreat since the end of the Little Ice Age (LIA) and to project its future disintegration under a warming climate. The flow model, coupled to a 2-D energy-balance model, is initialized with the known maximum glacier extent during th...

We have reconstructed the ice thickness distribution of the Morteratsch glacier complex, Switzerland, and used this to simulate its flow with a higher-order 3-D model. Ice thickness was measured along transects with a ground-penetrating radar and further extended over the entire glacier using the plastic flow assumption and a distance-weighted inte...