Fifty years of satellite data pin 84% of polar ice loss on faster-flowing glaciers
The IMBIE team merged 42 independent satellite surveys from 27 missions to account for 11.3 trillion tonnes of ice lost from Greenland and Antarctica since 1979, and it assigns 84% of that loss to glaciers accelerating into the ocean.
The Scientist · Science desk
What happened
- The Ice Sheet Mass Balance Inter-comparison Exercise combined 42 independent satellite surveys from 27 missions, reaching back to 1972 for Greenland and 1979 for Antarctica through the early Landsat archive.
- Greenland and Antarctica shed 11,309 billion tonnes of ice between 1979 and 2023, enough to raise global sea level by 31.4 millimetres.
- Glaciers speeding up and discharging ice into the ocean drove 84% of that combined loss, with the remaining 16% coming from melting at the surface.
- The last four years of the record brought a temporary slowdown, with record snowfall over East Antarctica and a run of milder Greenland summers that roughly halved Greenland's surface melting.
Why it matters
- Who's exposed exposure The ice sheets now supply about a quarter of global sea level rise, so a growing share of coastal exposure is governed by how fast a small number of outlet glaciers move.
- What it limits constraint Sea-level projections cannot be tightened by better surface-melt physics alone: until ice dynamics are constrained, planners work with a high-end 2150 estimate 2.6 times higher than one that leaves ice-sheet instability out.
- Who has to decide decision The four most recent years are the ones a planner is most tempted to extrapolate, and the authors label them a short-term fluctuation against a clear long-term trend.
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Melting at the surface and ice flowing off the edge respond to different things. Melt follows summer air temperature over the ice sheet. Discharge follows how fast outlet glaciers move, and in Antarctica the IMBIE team attributes all of the continent's net loss to ocean melting of its outlet glaciers [8]. Otosaka, who led the study, said the pattern shows "the long-term trend is being driven by the dynamic response of the ice sheets to a warming ocean" [5].
In absolute terms, the flow share works out at roughly 9,500 billion tonnes of ice pushed into the ocean, against about 1,800 billion tonnes lost as surface meltwater [16]. Greenland supplied the larger part of the sea-level total. Antarctica's contribution is 13.3 millimetres [14]; subtracting that leaves 18.1 millimetres from Greenland [22].
The acceleration is legible in the decadal rates. Greenland was close to balance in the 1970s, and its 2010s loss rate was about 4.4 times its 1980s rate [7][20]. Antarctica went from around 48 billion tonnes a year in the 1980s to 202 billion in the 2010s [8], roughly 4.2 times [21]. Losses climb steeply from the 1990s onward [6].
In West Antarctica the flow term has not paused at all. Discharge there, led by Pine Island and Thwaites glaciers, rose in every decade of the record [9].
The record measures mass change and partitions it. It cannot say when discharge stops accelerating. Shepherd, who founded IMBIE and heads the School of Geography and Natural Science at Northumbria University, said: "Three centimeters (1.2 inches) of sea level rise may sound small, but that puts another six to nine million people at risk of coastal flooding and erosion." [10]
What the length buys is a test bed. The combined budget covers 44 years [17], long enough to ask whether an ice-sheet model reproduces the 1980s rates as well as the recent ones. Sutterley, the IMBIE co-lead, said satellites "give us continent-wide, year-on-year evidence of what is happening now, and that is exactly what we need to test models and narrow the uncertainties in projections of future sea level rise" [19].
On the reliability of the numbers themselves, Sutterley said: "The added length of the record, the larger pool of participating teams and our improved ability to assess uncertainties make this the most robust assessment of ice sheet mass balance produced so far." [18] The assessment was led from Northumbria University and the University of Washington Applied Physics Laboratory, supported by the European Space Agency and NASA, and published in Scientific Data [4].
What to watch
- Whether the record East Antarctic snowfall of 2020-2023 persists in the next IMBIE update, or the surface offset disappears.
- Whether Pine Island and Thwaites discharge keeps rising through the 2020s, which would extend the one unbroken trend in the record.
- Whether the next round of sea-level projections narrows the 2.6x high-end factor now that models can be scored against 44 years of mass balance.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence72
- Adoption
- Not scored
- Hype gap+6
- Incentives30
- Confidence72
Perspective Coverage
3 publishers- Builder
- Builder 48%
- Operator
- Operator 44%
- Investor
- Investor 8%
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
The Ice Sheet Mass Balance Inter-comparison Exercise (IMBIE) Team combined 42 independent satellite surveys, drawing on 27 satellite missions, reaching back to 1972 for Greenland and 1979 for Antarctica using the early Landsat archive.
- [2]
The two ice sheets lost 11,309 billion metric tons of ice between 1979 and 2023, pushing global sea level up by 31.4 millimetres.
- [3]
84% of the combined loss was driven by glaciers speeding up and pouring more ice into the ocean, with just 16% due to surface melting.
- [4]
The assessment was led by Dr Ines Otosaka and Professor Andrew Shepherd at Northumbria University and Dr Tyler Sutterley of the University of Washington Applied Physics Laboratory; it is supported by the European Space Agency and NASA and is published in the journal Scientific Data.
- [5]
Otosaka, who led the study, said: "By reaching back to the 1970s, we can now see how the ice sheets have changed across half a century. More than four-fifths of the ice lost was discharged into the ocean by faster-flowing glaciers, rather than melted at the surface, which tells us the long-term trend is being driven by the dynamic response of the ice sheets to a warming ocean."
- [6]
The record shows ice losses climbing steeply from the 1990s onward.
- [7]
Greenland, close to balance in the 1970s, saw its rate of loss rise from around 60 billion metric tons a year in the 1980s to 264 billion metric tons in the 2010s, a decade marked by repeated extreme summer melt events.
- [8]
Antarctica's rate of loss rose from around 48 billion metric tons a year in the 1980s to 202 billion metric tons in the 2010s, with all of its net loss caused by ocean melting of its outlet glaciers.
- [9]
West Antarctica's ice discharge, led by Pine Island and Thwaites glaciers, has risen in every decade of the record.
- [10]
Shepherd said: "Three centimeters (1.2 inches) of sea level rise may sound small, but that puts another six to nine million people at risk of coastal flooding and erosion. With the ice sheets set to lose much more ice in the decades ahead, global assessments like IMBIE are vital to protecting communities impacted by climate change."
- [11]
The most recent years, 2020 to 2023, brought a temporary slowdown in ice loss: record snowfall over East Antarctica offset some of the continent's glacier losses elsewhere, while a run of milder Greenland summers roughly halved its surface melting.
- [12]
Scientists caution that the 2020-2023 changes are short-term fluctuations against a clear long-term trend, not a reversal of ice loss.
- [13]
The ice sheets' response to a warming climate is the single largest source of uncertainty in sea level projections, and high-end estimates of global sea level rise by 2150 increase by a factor of 2.6 once the risk of ice-sheet instability is accounted for.
- [14]
Greenland accounted for the larger share of the loss, and Antarctica contributed 13.3 millimetres of sea level rise.
- [15]
The polar ice sheets are now responsible for around a quarter of all global sea level rise.
- [16]
The 84% dynamic share of the 11,309 billion tonne total is about 9,500 billion tonnes, and the 16% surface-melt share is about 1,800 billion tonnes.
- [17]
The combined Greenland and Antarctica mass budget spans 44 years.
- [18]
Sutterley said: "The added length of the record, the larger pool of participating teams and our improved ability to assess uncertainties make this the most robust assessment of ice sheet mass balance produced so far."
- [19]
Sutterley said: "Satellites give us continent-wide, year-on-year evidence of what is happening now, and that is exactly what we need to test models and narrow the uncertainties in projections of future sea level rise."
- [20]
Greenland's 2010s loss rate is about 4.4 times its 1980s rate.
- [21]
Antarctica's 2010s loss rate is about 4.2 times its 1980s rate.
- [22]
Greenland's contribution to the 31.4 millimetres of sea level rise is 18.1 millimetres.
Sources
3 independent publishers whose own reporting we read for this story.
- eos.orgWe’ve Lost 11 Trillion Metric Tons of Ice Since the 1980s
1 article · September 16, 2026
- newscientist.comSatellite data gives clearer picture of how ice sheets are losing mass
1 article · September 16, 2026
- phys.orgSpeeding glaciers drive half a century of polar ice loss
1 article · September 16, 2026
Topics and entities
Topics
- Ice sheet mass balance
- Sea-level rise
- Satellite Earth Observation
Entities
- University of Washington Applied Physics Laboratory
- Northumbria University
- Pine Island Glacier
- European Space Agency
- Michael Meredith
- British Antarctic Survey
- NASA
- Landsat
- Ice Sheet Mass Balance Inter-comparison Exercise
- Thwaites Glacier