Glacier Monitoring and Remote Sensing
Glaciology is, in the end, a measurement science. Every claim about glacier retreat, mass loss or sea-level contribution rests on numbers collected by someone, somewhere, with a measuring tape, a stake, a plane or a satellite. The toolkit has expanded enormously since the first surveys in the 19th century, and combining methods is what gives us the global picture.
Why monitoring matters
Glaciers are the cleanest indicator of climate change. They have no political agenda; they melt because they melt. A consistent global record of glacier change is one of the strongest empirical pillars of climate science.
In situ stake measurements
The classical method. Drill a stake into the ice in autumn, measure how much sticks out. Come back next autumn; the difference is the ablation. Combined with snow-pit measurements in the accumulation zone, this gives mass balance for that year.
GPR (ground-penetrating radar)
Walked, towed or flown across the ice surface. Reveals internal layering, bed topography and water content. Essential for converting surface measurements to total volume.
Airborne lidar
Aircraft-mounted laser ranging produces decimetre-accurate elevation models. Annual or biennial repeat flights over a glacier give volume change directly. Standard tool for monitored Swiss glaciers.
Satellite optical imagery
Landsat (1972-), Sentinel-2 (2015-), ASTER, planet-scale providers. Used for tracking terminus position, calving fronts, snowline and debris-covered area. Free and global.
Synthetic aperture radar (SAR)
Sentinel-1, RADARSAT, ALOS-PALSAR. Sees through cloud and at night. Used for ice velocity measurements via feature tracking and interferometry. Has revealed Antarctic and Greenland ice stream velocities at unprecedented detail.
Satellite altimetry
ICESat-1 (2003-2009), ICESat-2 (2018-), CryoSat-2 (2010-). Direct elevation measurement, especially over polar ice sheets. Vital for sea-level budget work.
GRACE and GRACE-FO
Gravity satellites. By measuring tiny variations in Earth's gravity field, they detect mass changes in ice sheets and large glacier systems. The principal source of independent mass-balance estimates for Greenland and Antarctica.
Drones (UAS)
Small drones now produce centimetre-resolution elevation models of individual glaciers. They have transformed monitoring of small research glaciers where traditional aircraft are too expensive.
Combining methods
No single technique tells the whole story. Stake measurements give local mass balance at sub-metre precision but cover only point locations. Satellites give global coverage at coarser resolution. Reanalysis combines them into a consistent global record.
Open data
GLAMOS (Swiss Glacier Monitoring), WGMS (World Glacier Monitoring Service), IMBIE (Ice Sheet Mass Balance Intercomparison) and many others publish data openly. Glacier science is one of the most transparent earth science disciplines.
From reading to planning
Filter to "monitored" on the interactive map for glaciers with active scientific monitoring, with links to public mass-balance records — useful for serious students of glacier change.