Regine Hock

University of Alaska Fairbanks · Geophysical Institute

Surging glaciers are glaciers that experience rapidly accelerated glacier flow over a comparatively short period of time. Though relatively rare worldwide, Alaska is home to the largest number of surge‐type glaciers globally. However, their impact on the broader socioecological system in the state is both poorly understood and under‐researched, whi...

Glaciers of Baffin Island and nearby islands of Arctic Canada have experienced rapid mass losses over recent decades. However, projections of loss rates into the 21st century have so far been limited by the availability of model calibration and validation data. In this study, we model the surface mass balance of the largest ice cap on Baffin Island...

The loss of glaciers affects sea level, water availability, and natural hazards resulting in socioeconomic impacts for communities around the world, even for those located far from these icy giants. Our study found that limiting future increases in global mean temperature to +1.5°C will still cause the loss of more than 25% of their current mass bu...

The Randolph Glacier Inventory (RGI) is a global inventory of glacier outlines including a set of attributes and other relevant auxiliary information. This user guide provides detailed documentation of the RGI version 7.0 but also includes general information on the RGI and its earlier versions.

The surface melting of the Greenland ice sheet has been increasing over the last decades due to Arctic atmospheric warming. Surface melt depends on the energy balance which includes the atmospheric forcing but also the thermal budget of the snow, firn and ice near the ice sheet surface. We present a compilation of more than 4500 measurements of ice...

Knowledge of frontal ablation from marine-terminating glaciers (i.e., mass lost at the calving face) is critical for constraining glacier mass balance, improving projections of mass change, and identifying the processes that govern frontal mass loss. Here, we discuss the challenges involved in computing frontal ablation and the unique issues pertai...

Increases in ocean temperatures in the Filchner Ronne region of Antarctica are likely to result in increased ice mass loss and sea level rise. We constrain projections of the 21st century sea level contribution of this region using process-based ice-sheet modeling, with model parameters controlling ice dynamics calibrated using observed surface spe...

A recent study (Millan and others, 2022 a , Nature Geoscience 15(2), 124–129) claims that ice volume contained in all glaciers outside the ice sheets and its potential contribution to sea level is 20% less than previously estimated. However, the apparent decrease is largely due to differences in choice of domain, as the study excludes 80% of the gl...

Glacier mass loss affects sea level rise, water resources, and natural hazards. We present global glacier projections, excluding the ice sheets, for shared socioeconomic pathways calibrated with data for each glacier. Glaciers are projected to lose 26 ± 6% (+1.5°C) to 41 ± 11% (+4°C) of their mass by 2100, relative to 2015, for global temperature c...

The increasing mass loss from the Greenland ice sheet is becoming growingly important to present-day global sea level rise. Meltwater export to the ocean may be amplified by near-surface ice layers in firn (i.e., snow that has survived at least one melt season) which prevent infiltration. Such ice layers have been documented at various sites in sou...

In the Northern Hemisphere, ~1500 glaciers, accounting for 28% of glacierized area outside the Greenland Ice Sheet, terminate in the ocean. Glacier mass loss at their ice-ocean interface, known as frontal ablation, has not yet been comprehensively quantified. Here, we estimate decadal frontal ablation from measurements of ice discharge and terminus...

Glacier monitoring has been internationally coordinated for more than 125 years. Despite this long history, there is no authoritative answer to the popular question: ‘Which glaciers are the largest in the world?’ Here, we present the first systematic assessment of this question and identify the largest glaciers in the world – distinct from the two...

Increased surface melt in the percolation zone of the Greenland ice sheet causes significant changes in the firn structure, directly affecting the amount and timing of meltwater runoff. Here we force an energy-balance model with automatic weather stations data at two sites in the percolation zone of southwest Greenland (2040 and 2360 m a.s.l.) betw...

To characterize the spatiotemporal variations of glacier surface speed on the Kenai Peninsula, Alaska (∼3,900 km²), we derived 92 surface speed fields between October 2014 and December 2019 using intensity offset tracking on Sentinel‐1 data. On average, speeds are 50% greater in spring (March‐May) than the annual mean (69 m a⁻¹) while winter speeds...

Passive microwave satellite observations are used to identify the presence of surface meltwater across Antarctica at daily intervals from July 1979 to June 2020, with a focus on ice shelves. Antarctic Peninsula ice shelves have the highest number of annual days of melt, with a maximum of 89 days. Over the entire time period, there are few significa...

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...

Supraglacial debris affects glacier mass balance as a thin layer enhances surface melting, while a thick layer reduces it. While many glaciers are debris-covered, global glacier models do not account for debris because its thickness is unknown. We provide the first globally distributed debris thickness estimates using a novel approach combining sub...

Concurrent with atmospheric warming glaciers around the world are rapidly retreating, thinning, and losing mass. While total volume compared with the ice sheets in Greenland and Antarctica is small, glaciers outside the ice sheets have contributed significantly to recent global sea level rise. On average, these glaciers experienced only slightly ne...

Passive microwave datasets have been used to quantify the extent and duration of surface melt in Greenland and Antarctica from 1978 on with daily and near-daily intervals. These results have important implications for climate analysis and may help evaluate ice shelf stability. However, the accuracy of passive microwave methods used to detect melt i...

Permafrost, a key component of Arctic ecosystems, is currently affected by climate warming and anticipated to undergo further significant changes in this century. The most pronounced changes are expected to occur in the transition zone between the discontinuous and continuous types of permafrost. We apply a transient temperature dynamic model to in...

Global sea level provides an important indicator of the state of the warming climate, but changes in regional sea level are most relevant for coastal communities around the world. With improvements to the sea-level observing system, the knowledge of regional sea-level change has advanced dramatically in recent years. Satellite measurements coupled...

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...

Glacier mass loss in Alaska has implications for global sea level rise, fresh water input into the Gulf of Alaska and terrestrial fresh water resources. We map all glaciers (>4000 km ² ) on the Kenai Peninsula, south central Alaska, for the years 1986, 1995, 2005 and 2016, using satellite images. Changes in surface elevation and volume are determin...

The response of glaciers to climate change has major implications for sea-level change and water resources around the globe. Large-scale glacier evolution models are used to project glacier runoff and mass loss, but are constrained by limited observations, which result in models being over-parameterized. Recent systematic geodetic mass-balance obse...

Extensive field observations were conducted in the Upper Susitna basin, a 13 289 km2 glacierized catchment in central Alaska in 2012–2014. This paper describes the comprehensive data set of meteorological, glacier mass balance, snow cover, and soil measurements, as well as the data collection and processing. Results are compared to similar observat...

Glaciers in High Mountain Asia are an important freshwater resource for large populations living downstream who rely on runoff for hydropower, irrigation, and municipal use. Projections of glacier mass change and runoff therefore have important socio-economic impacts. In this study, we use a new dataset of geodetic mass balance observations of almo...

This is the Summary for Policy Makers of the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate, as approved by the IPCC member countries at the Plenary in Monaco, 25 September 2019.

The cryosphere (including, snow, glaciers, permafrost, lake and river ice) is an integral element of high mountain regions, which are home to roughly 10% of the global population. Widespread cryosphere changes affect physical, biological and human systems in the mountains and surrounding lowlands, with impacts evident even in the ocean. Building on...

The Greenland Ice Sheet holds 7.2 m of sea level equivalent and in recent decades, rising temperatures have led to accelerated mass loss. Current ice margin recession is led by the retreat of outlet glaciers, large rivers of ice ending in narrow fjords that drain the interior. We pair an outlet glacier–resolving ice sheet model with a comprehensive...

Global-scale 21st-century glacier mass change projections from six published global glacier models are systematically compared as part of the Glacier Model Intercomparison Project. In total 214 projections of annual glacier mass and area forced by 25 General Circulation Models (GCMs) and four Representative Concentration Pathways (RCP) emission sce...

As part of a planned hydropower facility, extensive field observations were conducted in the Upper Susitna basin, a 13,289 km² glacierized catchment in central Alaska in 2012–2014. This paper describes a comprehensive data set of meteorological, glacier mass balance, snow cover and soil measurements, as well as the data collection and processing. R...

The International Association of Cryospheric Sciences (IACS) became the eighth and most recent association of IUGG at the general assembly in Perugia, Italy, in July 2007. IACS was launched in recognition of the importance of the cryosphere within the Earth system, particularly at a time of significant global change. It was the first new associatio...

The cryosphere (including, snow, glaciers, permafrost, lake and river ice) is an integral element of high mountain regions, which are home to roughly 10% of the global population. Widespread cryosphere changes affect physical, biological and human systems in the mountains and surrounding lowlands, with impacts evident even in the ocean. Building on...

Assessing and modeling precipitation in mountainous areas remains a major challenge in glacier mass balance modeling. Observations are typically scarce and reanalysis data and similar climate products are too coarse to accurately capture orographic effects. Here we use the linear theory of orographic precipitation model (LT model) to downscale wint...

Worldwide glacier retreat and associated future runoff changes raise major concerns over the sustainability of global water resources, but global-scale assessments of glacier decline and the resulting hydrological consequences are scarce. Here we compute global glacier runoff changes for 56 large-scale glacierized drainage basins to 2100 and analys...

Glaciers spanning large altitudinal ranges often experience different climatic regimes with elevation, creating challenges in acquiring mass-balance and climate observations that represent the entire glacier. We use mixed methods to reconstruct the 1991–2014 mass balance of the Kahiltna Glacier in Alaska, a large (503 km2) glacier with one of the g...

Surge-type Black Rapids Glacier, Alaska, has undergone strong retreat since it last surged in 1936–1937. To assess its evolution during the late Twentieth and Twenty-first centuries and determine potential implications for surge likelihood, we run a simplified glacier model over the periods 1980–2015 (hindcasting) and 2015–2100 (forecasting). The m...

The Susitna River draining from the highly glacierized Central Alaska Range has repeatedly been considered a potential hydro-power source in recent decades, raising questions about the effect of glacier changes on the basin’s river runoff. We determine changes in the glacier area (1951–2010), elevation (1951–2010, 1951–2005 and 2005–2010), equilibr...

Estimating the long-term mass balance of the high-Arctic Svalbard archipelago is difficult due to the incomplete geodetic and direct glaciological measurements, both in space and time. To close these gaps, we use a coupled surface energy balance and snow pack model to analyse the mass changes of all Svalbard glaciers for the period 1957–2014. The m...

We determine the geodetic mass balance of surge-type Black Rapids Glacier, Alaska, for the time periods 1980–2001 and 2001–2010 by combining modern InSAR-derived DEMs, DEMs derived from archival aerial imagery, laser altimetry data and in-situ surface elevation measurements. Our analysis accounts for both the large rockslides and terrain displaceme...

Longterm mass balance of all glaciers of the high Arctic Svalbard archipelago is difficult to achieve due to spatial and temporal incompleteness of geodetic and direct glaciological measurements. To close these gaps, we use a coupled surface energy balance and snow pack model to analyze Svalbard glacier mass changes and its evolution for the period...

We study the evolution of the Juneau Icefield, one of the largest icefields in North America (>3700 km 2 ), using the Parallel Ice Sheet Model (PISM). We test two climate datasets: 20 km Weather Research and Forecasting Model (WRF) output, and data from the Scenarios Network for Alaska Planning (SNAP), derived from spatial interpolation of observat...

The anticipated retreat of glaciers around the globe will pose far-reaching challenges to the management of fresh water resources and significantly contribute to sea-level rise within the coming decades. Here, we present a new model for calculating the twenty-first century mass changes of all glaciers on Earth outside the ice sheets. The Global Gla...

We present a detailed, complete glacier inventory for Alaska and neighboring Canada using multi-sensor satellite data from 2000 to 2011. For each glacier, we derive outlines and 51 variables, including center-line lengths, outline types and debris cover. We find 86 723 km2 of glacier area (27 109 glaciers >0.025 km2), ∼12% of the global glacierized...

Lake-calving Yakutat Glacier in southeast Alaska, USA, is undergoing rapid thinning and terminus retreat. We use a simplified glacier model to evaluate its future mass loss. In a first step we compute glacier-wide mass change with a surface mass-balance model, and add a mass loss component due to ice flux through the calving front. We then use an e...

Our incomplete knowledge of the proportion of mass loss due to frontal ablation (the sum of ice loss through calving and submarine melt) from tidewater glaciers outside of the Greenland and Antarctic ice sheets has been cited as a major hindrance to accurate predictions of global sea level rise. We present a 28 year record (1985–2013) of frontal ab...

Juneau Icefield covers 3900 km2 in the Coast Mountains on the border between Alaska and British Columbia. It has shown substantial mass loss in the last century. There have been a multitude of field campaigns on Juneau Icefield (including the well-known Juneau Icefield Research Project), so the data coverage is comparatively good. In addition there...

The mass budget of the ice caps surrounding the Antarctica Peninsula and, in particular, the partitioning of its main components are poorly known. Here we approximate frontal ablation (i.e. the sum of mass losses by calving and submarine melt) and surface mass balance of the ice cap of Livingston Island, the second largest island in the South Shetl...

Matthias Huss is an outstanding young glaciologist who completed his Ph.D. in 2009 at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, and currently has a joint appointment there and at the University of Fribourg. During his short scientific career, Matthias has made substantial and innovative contributions to a broad range o...

Coincident with atmospheric warming, glaciers have retreated and thinned around the world. Enhanced glacier melt is the primary cause for the decline of the world’s mountain glaciers. However, rapid and large increases in ice discharge into the oceans, possibly driven by warmer ocean waters, have accelerated the net mass loss of the ice sheets in G...

The Randolph Glacier Inventory (RGI) is a globally complete collection of digital outlines of glaciers, excluding the ice sheets, developed to meet the needs of the Fifth Assessment of the Intergovernmental Panel on Climate Change for estimates of past and future mass balance. The RGI was created with limited resources in a short period. Priority w...

The Randolph Glacier Inventory (RGI) is a globally complete collection of digital outlines of glaciers, excluding the ice sheets, developed to meet the needs of the Fifth Assessment of the Intergovernmental Panel on Climate Change for estimates of past and future mass balance. The RGI was created with limited resources in a short period. Priority w...

[1] The hydrology of many important river systems in the world is influenced by the presence of glaciers in their upper reaches. We assess the global-scale response of glacier runoff to climate change, where glacier runoff is defined as all melt and rain water that runs off the glacierized area without refreezing. With an elevation-dependent glacie...

Alaskan glaciers are among the largest regional contributors to sea-level rise in the latter half of the 20th century. Earlier studies have documented extensive and accelerated ice wastage in most regions of Alaska. Here we study five decades of mass loss on high-elevation, land-terminating glaciers of the Wrangell Mountains (∼4900 km2) in central...

This study presents a new method to derive centerlines for the main branches and major tributaries of a set of glaciers, requiring glacier outlines and a digital elevation model (DEM) as input. The method relies on a "cost grid–least-cost route approach" that comprises three main steps. First, termini and heads are identified for every glacier. Sec...

[1] A significant portion of the world's glacier ice drains through tidewater outlets, though much remains unknown about the response to recent climate change of tidewater glaciers. We present a 64 year record of length change for 50 Alaska tidewater glaciers. We use USGS topographic maps to provide a base length for glaciers before 1970. Using all...

As glaciers retreat, they highly alter the characteristics of the overall water budget of the larger drainage basin. Understanding and quantifying glacier melt is key to effectively project future changes in watershed-scale stream flow from glacierized landscapes. In glacierized Southcentral Alaska, the State of Alaska is reviving analyses of the S...

Changes in mass contained by mountain glaciers and ice caps can modify the Earth's hydrological cycle on multiple scales. On a global scale, the mass loss from glaciers contributes to sea-level rise. On regional and local scales, glacier meltwater is an important contributor to and modulator of river flow. In light of strongly accelerated worldwide...

Many glaciological and hydrological studies require outlines of individual glaciers rather than total ice cover. Here we develop a new semi-automatic algorithm that uses a digital elevation model (DEM) and outlines of glacier complexes to calculate the extents of individual glaciers. The algorithm first applies hydrological modeling tools to a modi...

This study presents a new method to derive centerlines for the main branches and major tributaries of a set of glaciers, requiring glacier outlines and a digital elevation model (DEM) as input. The method relies on a "cost grid - least cost route approach" that comprises three main steps. First, termini and heads are identified for every glacier. S...