Greenland’s ice sheet shrank for the 30th year in a row, losing about 135 billion tonnes

Greenland’s ice sheet lost mass for the 30th year in a row in the 2025-26 ice cycle, which ran from 1 September 2025 to 31 August 2026. The Danish Meteorological Institute puts the net loss at about 135 billion tonnes of ice. The last year that ended with a net gain was 1996, so every annual tally since the mid-1990s has come out negative.

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The season was not a record breaker. Surface mass balance, which is snowfall minus melt and runoff, came in around 519 billion tonnes, the sixth highest in a 46-year dataset. A loss still showed up in the totals because the ice sheet also sheds mass through calving and glacier flow, and those losses do not hinge on a single summer’s weather.

Two estimates, 135 billion tonnes and 173 billion

Climate scientists Martin Stendel and Ruth Mottram of the DMI wrote up the season in a guest post for Carbon Brief, and they report two totals. The first, about 135 billion tonnes, comes from a three-model average method described in a 2021 paper in Earth System Science Data. The second, new this year, is about 173 billion tonnes and rests on a single climate model checked against automatic weather stations, satellites, GPS and aircraft observations. The authors say the gap reflects how incompletely ice thickness, flow speed and surface melt rates are known.

The Geological Survey of Denmark and Greenland published the 173 billion tonne figure as its own assessment. Senior researcher Signe Hillerup Larsen said the picture is clear, with the ice sheet losing mass year after year, and that a warmer climate should keep that going. The survey counts about 130 billion tonnes lost in 2024-25 and a record of roughly 458 billion tonnes in 2012.

How the number is built matters. Surface mass balance, supplied by the DMI through its Polar Portal, counts snowfall against melt and meltwater runoff. Ice-dynamic loss, the mass carried to the coast by glaciers and shed as icebergs, is added using satellite measurements of ice height and ice movement from DTU Space. The survey completes the annual assessment around 1 September, drawing on automatic weather stations, GPS, aerial surveys and model calculations under the PROMICE and GC-Net programmes, with independent checks from satellite height and gravity-field changes.

A blocked jet stream and a 74.9% peak melt day

Melt began on 5 June, nine days later than the 1981-2010 average, and peaked on 22 July when melting covered 74.9% of the ice sheet. The record is 81.2%, set in July 2025. Winter and early spring were dry in the south, which left about 40 billion tonnes less snow than normal.

Stendel and Mottram credit an omega-shaped blocking pattern in the jet stream that kept Greenland on the cooler side while heatwaves struck Europe and North America. They say a shift of half a wavelength would probably have produced record melt and a much lower surface mass balance. Stendel told GEUS that the distinctive feature of the year’s weather was its stark contrasts, with early-season snowfall and refreezing offsetting part of the June and July melt.

Petermann’s 76 square kilometre iceberg

On 4 August 2026 a tabular iceberg of more than 76 square kilometres and about 150 metres thick broke from the floating tongue of Petermann Glacier in north-west Greenland. According to the authors it was the largest floating-ice loss at Petermann since 2012 and the largest calving by any Arctic glacier since 2020. ScienceDaily reported that two more ice islands, of about 94 and 84 square kilometres, are expected to detach and would together remove about 22% of the remaining floating ice. Floating ice does not raise sea level directly, but Petermann acts as a brake on inland ice flow. A study hosted by Nature that the authors cite attributes roughly two-thirds of Greenland’s total ice loss to calving and glacier retreat.

Greenland in the 32-millimetre sea-level tally

The survey puts the cumulative loss from 1986-87 through 2025-26 at about 6,205 billion tonnes, equal to roughly 17.4 millimetres of global sea-level rise. If the entire ice sheet melted, the rise would be around 7.4 metres, a figure that frames how much frozen water is still in place.

The Ice Sheet Mass Balance Intercomparison Exercise, or IMBIE, combined 42 independent estimates in a dataset published in Scientific Data in September 2026. From 1979 to 2023, Greenland and Antarctica together lost 11,309 billion tonnes, raising global sea level by about 32 millimetres, close to a quarter of the observed rise. Greenland alone lost 6,215 billion tonnes between 1972 and 2023, about 119 billion tonnes a year, with roughly two-thirds from ice discharge and one-third from reduced surface mass balance.

Melt-related losses climbed from about 60 billion tonnes a year in the 1980s to 264 billion tonnes a year in the 2010s, and the past two years each lost more than 100 billion tonnes. Antarctica lost 4,780 billion tonnes over the same period, adding about 13 millimetres, mostly through discharge in West Antarctica while East Antarctica has been comparatively stable. The authors note that its ice sheet is roughly ten times larger than Greenland’s, so it could drive far more future rise, and they describe growing Antarctic melt, sea ice loss, ice shelf loss and glacier retreat as the Greenlandification of Antarctica.

Whether the DMI’s 135 billion and the survey’s 173 billion converge as later observations arrive is an open question. Both land on the same sign for the 30th time.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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