The world is losing about 630 billion tonnes of ice a year

The world’s ice caps are shrinking by a massive 630 billion tonnes a year³⁴. “Ice caps” here means all the ice that rests on land: the two continent-sized ice sheets covering Greenland and Antarctica, and the glaciers everywhere else.

It is a net figure. Snow adds new ice every year, and ice is lost to melting and to icebergs breaking off into the sea. The 630 billion tonnes is the gap between the two, averaged over the ten years to 2023.

Nobody publishes this total as a single number. It is put together from two records, satellite measurements of the ice sheets and the World Glacier Monitoring Service’s tally for glaciers, and “How this number was made” explains how.

About 20,000 tonnes of ice are lost every second

Spread evenly through the year, the loss comes to about 20,000 tonnes of ice every second, or 1.7 billion tonnes a day. Stacked into one block, a single year’s loss would make a cube of ice nearly nine kilometres along each side, about as tall as Mount Everest.

The real loss is nowhere near that even. Most of the melting happens in summer, and whole years differ: since 2010 the yearly total has swung between about 480 and 900 billion tonnes³⁴.

At the conversion the IPCC uses, that much ice raises the sea by about 1.7 millimetres a year⁷.

Around 1980 the world’s ice was close to balance

Forty-odd years ago the world’s ice was shrinking far more slowly. In the 1980s Greenland was losing about 60 billion tonnes a year and Antarctica about 48³. The glaciers beyond those two lost about 60 billion tonnes a year in the decade to 1985, and in some years glaciers worldwide gained ice⁴. Together that is roughly a quarter of today’s rate.

The loss has not climbed in a straight line since. Between the decade to 2013 and the decade to 2023, glaciers’ losses grew by about a third⁴ while the ice sheets’ shrank by more than a quarter³, and the total came out slightly lower. The ice sheets’ dip looks temporary.

Against the whole store the yearly loss is tiny. Antarctica holds about 27 million cubic kilometres of ice¹⁴, Greenland about 2.9 million¹⁵ and the glaciers about 158,000⁶. A year’s loss is roughly 0.002% of that.

Most of the ice sheets’ loss is ice sliding into the sea, not melting in place

“Melting” is only part of it. An ice sheet gains ice as snowfall and loses it in two ways: meltwater runs off its surface, and solid ice flows through outlet glaciers (the fast-moving rivers of ice at its edges) into the sea⁷.

Since 1979, 84% of the two ice sheets’ net loss has come from their own ice flowing faster into the sea. Extra melting at the surface caused the other 16%³.

The ocean drives it. Where an ice sheet meets the sea, its glaciers often end in floating platforms called ice shelves, which brace the ice behind them. Warming seawater melts the shelves from below and eats at glacier fronts. As that support thins or breaks away, the ice upstream speeds up⁷.

The clearest case was in 2002, when more than 3,000 square kilometres of Antarctica’s Larsen B ice shelf broke apart within weeks. The shelf was already floating, so its collapse added nothing to the sea by itself. The glaciers that had fed it then accelerated¹⁶.

Greenland is losing more ice than Antarctica

Greenland is losing more: about 205 billion tonnes a year over the decade to 2023, against Antarctica’s 131³. It has lost more in every decade since the 1980s except the 1990s, when the two were level within the margin of error. Since 1979 Greenland’s ice has raised the sea by 1.8 centimetres and Antarctica’s by 1.3¹².

The two lose ice differently. In Antarctica all of the net loss comes from faster flow. Most of it is in West Antarctica, where losses rose every decade, from about 29 billion tonnes a year in the 1980s to 163 in the 2010s³, led by the Thwaites and Pine Island glaciers⁸. East Antarctica has stayed close to balance.

Greenland loses ice both ways. Over the past half century about two-thirds of its loss came from faster flow and a third from surface melt, but the 2010s were the first decade in which the melting took more than the flow³. The Intergovernmental Panel on Climate Change (IPCC) expects melt to dominate more and more as Greenland’s glaciers retreat from the sea⁷.

Both ice sheets lost less in 2020 to 2023: Greenland about 199 billion tonnes a year and Antarctica only about 59. Greenland had no extreme melt summers. In Antarctica, record snowfall over the east in 2022 and 2023 offset the west, where the flow into the sea rose by a further 38%³.

One study traced that snowfall to a pattern of tropical ocean warming that comes round about once a decade, and called the gain probably temporary¹³. The European Union’s Copernicus climate service has Antarctica losing ice again, 56 billion tonnes in 2023 and 82 billion in 2024⁸. The scientists behind the ice sheet record call the lull short-term variation, not a reversal¹².

You may see higher numbers for Greenland. NASA gives about 264 billion tonnes a year⁹. That is an average since 2002 from one kind of satellite, and it takes in the peak years of 2010 to 2012.

Glaciers hold half a percent of the ice and account for nearly half the loss

The world’s glaciers have lost about 9,600 billion tonnes of ice since 1975⁵. About 6,500 billion of that went between 2000 and 2023 alone, roughly 5% of all the glacier ice there was⁶.

Glaciers are a sliver of the planet’s ice, about half a percent of it. They account for nearly half the yearly loss: about 290 of the 630 billion tonnes, or 345 if the glaciers fringing Greenland and Antarctica are counted with them⁴. Over 2002 to 2021 glaciers lost about 18% more ice than the Greenland ice sheet, and more than twice as much as Antarctica⁶.

Size is the likely reason. Small, steep glaciers answer to a warmer climate within years, where an ice sheet takes centuries⁷.

Their loss is speeding up. It averaged less than 100 billion tonnes a year from 1976 to 1995, around 230 over the next two decades, and 390 from 2016 to 2025. Six of the seven most recent years are among the worst on record⁵, and the worst of all was 2023, at about 555 billion tonnes⁴.

Every one of the world’s 19 glacier regions lost ice between 2000 and 2023. Alaska lost the most in tonnes, more than a fifth of the total, and Central Europe the most for its size⁶.

Switzerland has lost nearly a fifth of its glacier ice in five years

The loss is easiest to see in single places. Swiss glaciers lost more than 5% of their volume in 2026 alone and nearly 20% in the past five years. Several small ones, among them Bella Tola and Griessfirn, vanished completely¹⁷.

Some countries have run out. When the Humboldt glacier went in 2024, Venezuela became the second country in the world to lose all of its glaciers, according to the World Meteorological Organization¹⁸.

Iceland has marked a lost glacier with a plaque. Okjökull covered about 38 square kilometres in 1901 and 3 by 1978. It was declared dead in 2014, and the memorial went up in 2019¹⁹.

Those are single cases, picked because they are stark.

Melting sea ice barely raises the sea

Sea ice is not part of the 630 billion tonnes, and melting it barely raises the sea. It already floats, and floating ice displaces its own weight in water. There is one small exception: sea ice is nearly fresh, so its meltwater takes up about 2.6% more room than the salt water it displaced²⁰.

Sea ice matters because it reflects sunlight. Open ocean reflects about 6% of the sun’s energy and sea ice 50 to 70%²², so less ice means more heat absorbed. That is one of the proposed reasons the Arctic has warmed nearly four times as fast as the planet as a whole since 1979²³.

The Arctic’s summer ice has shrunk by 11.6% a decade since 1979², and the 20 smallest September minimums in the satellite record are the last 20 years¹.

Lately the decline has stalled. The record low still dates from 2012¹, and one study found no statistically significant decline in September ice since 2005. Its authors put the pause down to natural swings masking the human-caused loss. They think it could last another five to ten years, and that the odds of a faster drop afterwards have gone up²¹.

The IPCC says the Arctic Ocean will likely be practically free of sea ice for the first time, at its late-summer low, before 2050 in every scenario it considered. It sees no tipping point in that loss⁷.

Sea ice follows the temperature closely, in both directions. Ice on land is slower to go and far slower to return, and its loss is the one that raises the sea.

About half the world’s glacier ice can still be saved, or only a quarter

The ice sheets’ lull in the early 2020s does not look like a turn. Through those same years the flow of ice into the sea off West Antarctica rose by more than a third³, and glaciers lost more in the decade to 2025 than in any earlier decade on record⁴.

Some further loss is already locked in. Glaciers are still catching up with the warming so far. One study using eight glacier models found they would eventually lose 39% of the ice they had in 2020 even if temperatures stayed where they are now²⁵.

How much more goes depends on the warming. The same study found that 53% of today’s glacier ice would survive in the long run if warming is held to 1.5 °C. On current policies, which lead to about 2.7 °C, 24% would²⁵. Every extra tenth of a degree costs roughly another 2%²⁶.

Within this century the range is narrower but still wide. Glaciers are projected to lose 26% of their mass by 2100 at 1.5 °C of warming and 41% at 4 °C. Between half and four-fifths of all individual glaciers would disappear²⁷, presumably because the small ones go first.

A rough extrapolation, not a forecast, shows how differently the two kinds of land ice are placed. At the recent pace the glaciers’ whole store would last about four centuries. The ice sheets’ would last tens of thousands of years.

Ice loss as a whole has no single line to stay under. The ice sheets have tipping points of their own, which are part of the temperature story. So far their loss has been driven mostly by the ocean around them, though in Greenland melting at the surface is catching up. For glaciers, each fraction of a degree that CO2 in the air adds or spares seems to translate fairly directly into ice.