Glaciologists' Tools and Field Methods
Glaciology is one of the most fieldwork-intensive earth sciences. Its subjects are remote, cold, physically demanding to access, and often actively dangerous. The methods used to study glaciers reflect this reality: some are elegantly simple — stakes drilled into ice and read by eye twice a year — while others represent the cutting edge of remote sensing technology, capable of detecting centimetre-scale surface changes from orbital altitudes. Together, they provide a richly layered picture of ice as a dynamic material responding to its environment in real time.
Understanding how glaciologists work is useful not only for those considering careers in the field but for anyone who wants to evaluate the confidence level of glacier measurements and projections. The quality of a glacier model is only as good as the field data used to calibrate and validate it. The map shows where the world's glaciers are distributed, giving context to the extraordinary logistical challenges involved in maintaining field measurement programs in remote glaciated regions.
Mass Balance Stakes
The mass balance stake is the oldest and most fundamental instrument in operational glaciology. A stake is a metal or composite pole drilled several metres into glacier ice, protruding above the surface. The snow or ice surface level relative to the stake is measured at the end of the accumulation season (typically spring) and the end of the ablation season (typically autumn), recording how much mass has been added or lost at that point on the glacier. Networks of stakes distributed across the glacier, combined with density measurements in snow pits at accumulation zone sites, allow calculation of the spatially averaged specific mass balance.
The World Glacier Monitoring Service in Zurich maintains the global archive of stake-based mass balance records. The longest continuous records, including those for Storglaciaren in Sweden (monitored since 1945), Careser in Italy, and Wolverine Glacier in Alaska, provide invaluable multi-decadal perspectives on glacier change that satellite records, only available since the early 1970s at best, cannot replicate.
Ice Drilling and Core Analysis
Ice cores are cylindrical samples of glacier ice extracted by hollow drilling equipment, preserving the layered record of past snowfall. The deepest ice cores — from the Vostok Station and EPICA Dome C in Antarctica — extend more than 3 kilometres in depth and record climate conditions spanning 800,000 years. Shallower cores from alpine glaciers capture centuries of environmental history.
The drilling equipment for shallow alpine cores is portable and can be transported by helicopter or backpack to remote accumulation zones. A typical shallow core drill weighs 20 to 40 kilograms with associated equipment and can extract cores of 8 to 10 centimetres diameter at several metres per hour. Deep ice core drilling in Antarctica uses electromechanical drills operating inside heated enclosures, extracting metre-long core sections that are logged, sectioned, and shipped frozen to laboratories.
Ground-Penetrating Radar
Ground-penetrating radar (GPR) uses high-frequency radio waves transmitted downward through glacier ice to map internal structures and the glacier bed. The time between transmission and return of reflected pulses, combined with the known speed of radar waves through ice, provides depth measurements. Towing a GPR antenna across a glacier surface on skis or behind a snowmobile generates continuous depth profiles that, when collected on a grid pattern, produce three-dimensional maps of glacier thickness.
GPR is essential for calculating glacier volume — the total amount of ice contained — which is required for any meaningful assessment of future sea level contribution or water storage capacity. The technique can also identify internal layering, crevasse networks beneath snow cover, englacial water pockets, and the transition between cold and temperate ice.
Automatic Weather Stations
Automatic weather stations (AWS) deployed on and near glaciers provide continuous records of the meteorological variables that drive mass balance: air temperature, relative humidity, incoming and outgoing solar radiation, wind speed and direction, and precipitation. On the glacier surface itself, ablation stakes and sonic distance sensors measure surface lowering in near-real time, transmitting data via satellite to laboratories.
The Swiss Federal Institute for Forest, Snow and Landscape Research (WSL/SLF) and partners operate extensive AWS networks in the Alps. The PROMICE network operates similar stations across the Greenland Ice Sheet margin. Data from these stations feeds directly into the models used for mass balance calculation and ice flow simulation.
Satellite Remote Sensing
The transformation of glacier science over the past three decades has been driven substantially by satellite remote sensing. Several distinct satellite technologies contribute different information types:
Optical imagery from instruments including Landsat (operational since 1972), Sentinel-2, and ASTER allows mapping of glacier outlines, terminus positions, snow line elevation, and ice surface features. Time series of Landsat imagery have been used to document glacier retreat globally, providing the historical record against which current observations are interpreted.
Synthetic aperture radar (SAR) from satellites including Sentinel-1, RADARSAT, and TerraSAR-X can penetrate cloud cover and darkness, providing imagery regardless of weather or polar night. SAR interferometry (InSAR) compares phase differences between radar images taken days apart to measure surface displacement at centimetre precision, mapping glacier flow velocities and detecting subtle elevation changes.
Laser altimetry from ICESat (2003 to 2009) and ICESat-2 (2018 to present) measures surface elevation with centimetre accuracy across ice sheet surfaces and mountain glaciers, providing precise records of surface lowering over time.
Borehole Studies
Boreholes drilled through glaciers to the bed serve multiple purposes. Temperature sensors lowered into boreholes measure the thermal structure of the ice — whether it is at the pressure melting point (temperate ice) or below (cold ice). Borehole tiltmeters measure internal ice deformation, separating the contribution of internal flow from basal sliding to total glacier velocity. Basal water pressure sensors record conditions at the glacier bed that control sliding speed, providing insight into the hydraulic mechanisms that govern fast ice flow.
Boreholes in the Swiss Alps, drained in the 1990s and 2000s by researchers at ETH Zurich and the University of Zurich, have been particularly informative about the thermal regime and subglacial hydrology of temperate Alpine glaciers. Similar work at Storglaciaren in Sweden has contributed fundamental understanding of polythermal glaciers — those with both temperate and cold ice zones.
Glacier Photography and Photogrammetry
Repeat photography at fixed stations near glacier termini provides the most visually intuitive record of glacier change and has been central to communicating glacier retreat to the public. The Swiss Glacier Monitoring Network (GLAMOS) maintains a photographic archive stretching back to the late nineteenth century for many major Alpine glaciers, allowing the visualisation of retreat at decadal timescales.
Structure-from-motion photogrammetry — creating three-dimensional surface models from overlapping photographs taken from multiple angles, now typically from drones — has become an affordable and rapid method for producing high-resolution digital elevation models of glacier termini and proglacial environments. A drone survey that would have required expensive aerial photography campaigns a decade ago can now be accomplished by a field team in a few hours with equipment carried in a backpack.
Modelling and Field Data Integration
The ultimate purpose of these diverse field measurements is to parameterise, calibrate, and validate ice flow and mass balance models. Ice flow models based on the Stokes equations of viscous fluid dynamics simulate glacier evolution over decades and centuries. They require inputs of ice thickness, bed topography, ice temperature, and surface mass balance, and they are validated against observed changes in terminus position, surface elevation, and velocity.
The integration of ground-based field measurements with satellite remote sensing and model outputs has produced the most comprehensive picture of global glacier change yet assembled. The IPCC's assessments draw directly on this integrated evidence base to produce the projections of glacier contribution to sea level rise that inform coastal adaptation planning worldwide.