| DAILY NEWS FOR YOU CLIMATE / ICE SHEETS |
| |
Polar Ice Loss Is Accelerating. A 47-Year Satellite Record Shows Most of It Is Being Driven by Faster-Flowing Glaciers. |
| Greenland and Antarctica have lost more than 11 trillion metric tons of ice since 1979. The new record shows that most of that loss came from glaciers dynamically discharging ice into the ocean — not simply from melting at the surface. |
| POLAR ICE / MASS-BALANCE RECORD | | 11.3T TONNES LOST | 84% DYNAMIC LOSS | 3.1 CM SEA-LEVEL RISE | | |
| Scientists have assembled the longest consistent satellite record yet of changes in Earth's two largest ice sheets — and the result shows a clear acceleration in ice loss across recent decades. |
| Between 1979 and 2023, Greenland and Antarctica together lost an estimated 11,309 billion metric tons of ice. That loss alone raised average global sea level by approximately 3.1 centimeters. |
| THE BIG DISTINCTION MOST OF THE ICE WAS NOT LOST THROUGH SURFACE MELTING. Researchers attribute about 84% of the combined loss to ice-dynamical imbalance — glaciers carrying more ice from the interior of the sheets into the ocean than snowfall can replace. | |
| TWO WAYS AN ICE SHEET LOSES MASS | | |
| SURFACE MASS BALANCE SNOW IN
MELTWATER OUT Snowfall adds mass. Surface melting and runoff remove it. | DYNAMIC IMBALANCE ICE FLOWS
INTO OCEAN Glaciers discharge solid ice through their coastal outlets. | |
| 84% — DYNAMICAL IMBALANCE | 16% | |
| That distinction matters because glacier flow can continue transferring ice into the ocean even when a particular summer is relatively mild. It also responds to changes where ice, rock and ocean interact — a system that behaves differently from simple surface melting. |
| |
| WARMER
OCEAN | → | ICE MARGIN
THINS | → | GLACIER
SPEEDS UP | → | MORE ICE
REACHES SEA | | |
| In Antarctica, the study found that net ice loss over the record was driven entirely by ocean-related melting and acceleration of outlet glaciers. West Antarctica has been particularly important, with ice discharge increasing in every decade of the satellite record. |
| Greenland experiences both processes: substantial surface melting during warm summers and the direct discharge of ice through fast-moving glaciers that terminate in the ocean. |
| THE ACCELERATION BY DECADE | | |
| GREENLAND ANNUAL LOSS | 60 Gt/YR
1980s | → | 264 Gt/YR
2010s | |
| ANTARCTICA ANNUAL LOSS | 48 Gt/YR
1980s | → | 202 Gt/YR
2010s | |
| Greenland was close to balance in the 1970s. By the 1980s, it was losing around 60 billion tonnes annually; during the 2010s, that figure had risen to roughly 264 billion tonnes per year. |
| Antarctica followed a similar trajectory, with average annual losses increasing from about 48 billion tonnes in the 1980s to approximately 202 billion tonnes in the 2010s. |
| 41B TONNES OF ICEBERGS / YEAR | JAKOBSHAVN / GREENLAND One of the fastest-moving glaciers on Earth illustrates how solid ice can be transferred directly from an ice sheet into the ocean. | |
| Jakobshavn Glacier in western Greenland is among the most dramatic examples. It produces roughly 41 billion metric tons of icebergs each year and has retreated at rates reaching about 50 meters per day during periods of rapid change. |
| WHAT 3.1 CENTIMETERS MEANS | | |
| 3.1 CM ADDED SINCE 1979 | GLOBAL AVERAGE This contribution comes from the two ice sheets alone, on top of sea-level rise from thermal expansion and other sources. | |
| Three centimeters sounds small until it is added to storm surge, tides and other components of rising seas. Even incremental increases in the ocean's baseline height allow flooding to reach farther inland during coastal events. |
| Greenland and Antarctica together now account for roughly one-quarter of global sea-level rise, according to the European Space Agency. |
| IMPORTANT DISTINCTION THIS STUDY MEASURES WHAT HAS HAPPENED. IT DOES NOT ISSUE A NEW 2050 OR 2100 SEA-LEVEL FORECAST. The dataset can be used to test and constrain future projections, but the paper itself should not be described as proving that existing official sea-level forecasts are already too low. | |
| |
| 27 SATELLITES | 45 INDEPENDENT SURVEYS | |
| The researchers combined 42 independent estimates of ice-sheet mass balance drawn from observations of changes in ice flow, volume and gravitational attraction. |
| The broader observational archive spans 27 satellites and 45 surveys, allowing scientists to extend Antarctica's record back to 1979 and Greenland's into the early 1970s. |
| |
| SHORT-TERM SIGNAL ICE LOSS SLOWED FOR SEVERAL YEARS — BUT THE LONG-TERM ACCELERATION DID NOT DISAPPEAR. Unusually heavy snowfall in East Antarctica and relatively mild Greenland summers temporarily offset part of the underlying losses. | |
| Between 2020 and 2023, total losses temporarily slowed. In East Antarctica, unusually large snowfall added mass, while a sequence of relatively mild summers reduced Greenland's surface melt. |
| Researchers describe that period as short-term variability rather than evidence that the multidecade trend has reversed. |
| ESTABLISHED / STILL UNCERTAIN | | |
| ESTABLISHED 11.3 trillion tonnes lost
3.1 cm sea-level contribution
Loss accelerated by decade
84% tied to ice dynamics | STILL UNCERTAIN Exact future acceleration
Timing of instability thresholds
Regional sea-level effects
Long-range glacier response | |
| WHY COASTS CARE ABOUT THE DATA BETTER HISTORICAL MEASUREMENTS REDUCE ONE SOURCE OF UNCERTAINTY IN FUTURE SEA-LEVEL MODELS. Coastal planning depends on estimates of how much water the ice sheets may contribute over the lifetime of roads, drainage systems, buildings, ports and flood defenses. | |
| THE SIGNAL THE IMPORTANT CHANGE IS NOT A SINGLE MELT SEASON. IT IS THE MULTIDECADE SHIFT FROM RELATIVELY STABLE ICE SHEETS TO A SYSTEM DISCHARGING HUNDREDS OF BILLIONS OF TONNES INTO THE OCEAN EACH YEAR. | |
| 03 | CORE NOTES What the new record establishes | |
| 01 | Greenland and Antarctica lost an estimated 11,309 billion metric tons of ice between 1979 and 2023, contributing about 3.1 centimeters to global mean sea level. | |
| 02 | About 84% of the combined loss came from dynamical imbalance — glaciers transporting ice into the ocean faster than the ice sheets could replace it. | |
| 03 | The study strengthens the observational record used to constrain future sea-level projections, but it does not itself publish a revised 2050 or 2100 sea-level forecast. | |
| |
| SOURCES Mass Balance of the Greenland and Antarctic Ice Sheets From the 1970s to 2023 — Scientific Data / Nature
Faster-Flowing Glaciers Fuel Decades of Polar Ice Loss — European Space Agency
See How Polar Glaciers Have Lost Trillions of Tons of Ice — The Washington Post
Satellites Show Earth Lost More Than 12 Trillion Tons of Ice From Greenland and Antarctica — Associated Press |
