# Under the Apuseni, ice at least 10,500 years old survives

*Scărișoara Cave, Apuseni Mountains*

A 1980 guidebook popularised 3,500 years; the research published in 2017 puts the minimum age at about 10,500. Go down the shaft, see how the ice outlasts summer, and read an archive of about 10,000 years of September–December conditions.

By Marius Comper · Published 19 September 2026

## The descent, chamber by chamber

The cave entrance is a 24 m high portal in the west wall of the shaft, about 60 m across; the pit is 47 m deep. Beyond the portal opens the Great Hall: its floor is an ice block of about 100,000 cubic metres.

Pick a chamber from the list or the drawing. Each chamber's label shows its climate zone, after Perșoiu and Pazdur (2011).

### The Shaft (transitional zone)

The collapsed pit that lets winter in: about 60 m wide and 47 m deep, with a year-round snow layer on its floor.

### The Great Hall (glacial zone)

The hall of the ice block, spread over about 3,000 square metres. The vertical ice walls divide three sectors: the Church and the two reserves.

### The Church (glacial zone)

The hall of over 100 perennial ice stalagmites; the floor drops about 8 m toward it from the Great Hall.

### The Great Reserve (periglacial zone)

The southern sector, with the roomiest halls, 20–45 m wide. The ice slopes down to 90 m below the surface; calcite crystals grow in the ice-free parts.

### Coman Gallery (warm zone)

The ice-free corridor of the warm sector, next to Sânziana's Palace.

### The Little Reserve (periglacial zone)

The northern sector, beyond an ice wall about 18 m high with visible layering; ice stalagmites rise here too.

## Why summer never melts it

The cave is a cold-air trap: a single entrance and mostly descending passages. The mechanism, described by Perșoiu and Pazdur in 2011, follows the seasons, and the ice budget changes from year to year.

### Winter

From November to April, dense cold air from outside sinks into the cave, dry and able to drop below −15 °C. This is how the cold that keeps the ice builds up.

### Autumn and spring

In mid-autumn, the shallow lake on the ice block freezes from top to bottom into lake ice, about 10–15 cm thick. In winter, water seeping through the ceiling adds floor ice on top.

### Summer

The density difference largely stops exchange with the warm outside air, and cave temperatures rarely pass +0.5 °C. From April, infiltrating warm water melts mostly the floor ice.

### The balance

The ice block never sits still: surface and side ablation, basal melting and lateral flow reshape it all the time. Levels run high in late spring and low in late summer, and wet summers melt it fast.

The Great Hall averages about −0.9 °C for the year; inflowing winter air can drop below −15 °C, and summer temperatures rarely pass +0.5 °C.

> In winter, dense cold air sinks through the descending passages; in summer, the density difference limits exchange with the warm air outside. Ponded water freezes in autumn into lake ice and in winter into floor ice.
>
> — Paraphrased from Perșoiu and Pazdur, The Cryosphere, 2011

## A chronology of at least about 10,500 years

The ice chronology spans at least about 10,500 cal BP years. Move the slider through the stops, from today's ice to the dated base; the table below gathers them all, newest first.

| Stop | What was happening |
| --- | --- |
| today | you are reading this piece |
| May–July 2019 | the ice level drops by about 35 cm |
| 2017 | the ice cores give the age of at least about 10,500 cal BP years |
| 2011 | the cold-trap mechanism is published |
| February 2003 | a 22.53 m core pierces the ice to the bedrock |
| 1947 | the Cluj team surveys the cave thoroughly |
| 1927 | Racoviță publishes the first scientific description of the glacier |
| the early 1920s | Racoviță studies the cave (1921–1923 or 1921–1925) |
| around 1850 | the Little Ice Age ends (1300–1850, after Perșoiu et al. 2017) |
| about 7,000–5,000 years ago | the warm peak of Holocene winters |
| 10,500 cal BP | the dated and modelled ice reaches at least this far |

> Radiocarbon dating of minute leaf and wood fragments preserved in the cave's ice indicates that its glacier is at least 10,500 years old, making it the oldest cave glacier in the world and one of the oldest glaciers on Earth outside the polar regions.
>
> — National Science Foundation, 27 April 2017

## Racoviță and the first century of research

Emil Racoviță studied the cave in the early 1920s (sources give 1921–1923 or 1921–1925) and published a preliminary scientific description of the glacier in 1927: <em>Observations sur la glacière naturelle dite „Ghețarul de la Scărișoara”</em>, in the Bulletin of the Cluj Society of Sciences. <em>Speologia</em>, also from 1927, is a separate popular work.

Seven years earlier, in 1920, Racoviță had founded in Cluj the first speleology institute in the world, which he led until 1947. That same year, four young Cluj researchers, M. Șerban, D. Coman, R. Givulescu and M. Pop, achieved a thorough exploration of the cave and described the glacier in better terms.

## What the ice cores say

Perșoiu and Onac's team, with colleagues from Belfast, Bremen and Stockholm, cored the ice block in February 2003 and reconstructed the Holocene winters from it: what they found and how they measured.

### Winters, rebuilt from isotopes

Oxygen and hydrogen isotopes in the ice were used to reconstruct air temperature from September to December, across about 10,000 years. It is the first continuous winter record for East-Central Europe, and the core top was given an estimated age: the year 1860 ± 20.

### Where the moisture came from

Deuterium excess was used to infer changes in moisture sources and shifts in winter storm tracks, between the Atlantic and the Mediterranean.

### The warm peak, then the chill

The mildest winters came about 7,000–5,000 years ago, after the 2017 summary; then the climate cooled gradually toward the Little Ice Age, from 1300 to about 1850.

### Leaves date the ice

Of 35 samples sent to the Poznań radiocarbon laboratory, 29 gave ages; the core chronology was built with the Bacon Bayesian software and covers almost the whole Holocene, between 10.5 and 0.090 kcal BP.

### The measured 2019 melt

Between May and July 2019, the ice level fell by about 35 cm (±0.3) across about 3,000 square metres: a loss of about 1,050 (±90) cubic metres, from infiltrating warm surface water. In 2017, the team planned to stretch the record to at least 13,000 years.

> Our reconstruction provides one of the very few winter climate reconstructions, filling in numerous gaps in our knowledge of past climate variability.
>
> — Bogdan Onac, National Science Foundation, 2017

## The cave in numbers

Every number in the piece, gathered in one table. The ice volume means about 40 pools of 50 × 25 metres at an assumed 2 m mean depth: 100,000 divided by 2,500.

| Measure | Value |
| --- | --- |
| Entrance altitude | 1,165 m |
| Passage length | 700 m (2011; guidebooks give 720) |
| Vertical range | 105 m |
| Shaft: width and depth | 60 m × 47 m |
| Entrance portal | 24 m |
| Ice block: surface | about 3,000 m² |
| Ice volume (2011, 2021) | about 100,000 m³ = about 40 pools |
| Volume in the 1980 guidebook | 75,000 m³ (historic value) |
| Ice wall in the Little Reserve | about 18 m |
| Stalagmites in the Church | over 100 |
| Temperature in the Great Hall | annual mean about −0.9 °C; winter below −15 °C; summer rarely above +0.5 °C |
| Age in the 1980 guidebook | 3,500 years (historic estimate) |
| Measured age (2017) | at least about 10,500 cal BP years |
| Loss of May–July 2019 | about 35 cm and about 1,050 m³ |
| The 2003 core | 22.53 m to the bedrock |

## Quiz: ice or history, which came first?

Six pairs from the chronology above. For each, choose whether the ice stop came earlier or later than the history stop.

1. **The glacier bottom.** The basal ice (10,500 cal BP) and the warm peak (about 7,000–5,000 years ago). *Earlier by millennia. The basal ice was already old when winters reached the warm peak.*
2. **The warm peak.** The warm peak (about 7,000–5,000 years ago) and the Little Ice Age (1300–1850). *Earlier by millennia. The warm peak had long passed when the Little Ice Age began.*
3. **The Little Ice Age.** The end of the Little Ice Age (around 1850) and Racoviță's studies (the early 1920s). *Earlier by decades. The glacier had left its coldest recent spell when Racoviță arrived.*
4. **The team and the description.** The Cluj survey (1947) and Racoviță's description (1927). *Later by 20 years. Two decades after the 1927 description, the 1947 team surveyed the cave thoroughly.*
5. **The core and the mechanism.** The February 2003 coring and the cold-trap mechanism (2011). *Earlier by 8 years. The core came out in 2003, and the mechanism was published in 2011.*
6. **The melt summer.** The rains that melted the ice (May–July 2019) and the 10,500-year study (2017). *Later by 2 years. Two years after the 2017 study, the level fell by about 35 cm, a loss of about 1,050 cubic metres.*

## Sources and how the numbers were computed

Calendar years count as usual, and radiocarbon ages are given in cal BP years, meaning calibrated years before 1950. The far end of the chronology, 10,500 cal BP years, is the modelled age of the base, not an exactly dated annual layer.

The comparison pool measures 50 × 25 metres at an assumed 2 m mean depth, which is 2,500 cubic metres; 100,000 divided by 2,500 means about 40 pools. The World Aquatics standard now asks a minimum 2.5 m depth for Olympic 50 m pools, so the comparison is illustrative.

Sources do not agree on every number: the length is 700 m in Perșoiu and Pazdur (2011) and 720 in guidebooks; the shaft depth is 47 m in the 2011 and 2021 studies, 48 in Romanian guides and 50 in Irimuș et al.; the volume of about 100,000 cubic metres (2011, 2021) replaces here the old guide value of 75,000; Racoviță's field years are 1921–1923 or 1921–1925, depending on the source.

### Ice and climate

- [Perșoiu, Onac, Wynn, Blaauw, Ioniță, Hansson (2017). *Holocene winter climate variability in Central and Eastern Europe*, Scientific Reports 7:1196: the February 2003 core, the 10.5 to 0.090 kcal BP chronology, the isotopes, the AD 1300–1850 Little Ice Age](https://doi.org/10.1038/s41598-017-01397-w)
- [Perșoiu, Pazdur (2011). *Ice genesis and its long-term dynamics in Scărișoara Ice Cave, Romania*, The Cryosphere 5, 45–53: the cold trap, the 700 m and 105 m cave, the roughly 100,000 cubic metre block, the temperatures](https://doi.org/10.5194/tc-5-45-2011)
- [Perșoiu, Onac, Wynn, Bojar, Holmgren (2011). *Stable isotope behavior during cave ice formation by water freezing in Scărișoara Ice Cave*, J. Geophys. Res. 116: ice formation by water freezing and stable-isotope behavior](https://doi.org/10.1029/2010JD014477)
- [Perșoiu et al. (2021). *Record summer rains in 2019 led to massive loss of surface and cave ice in SE Europe*, The Cryosphere 15, 2383–2399: the roughly 35 cm drop of May–July 2019 and the roughly 1,050 cubic metre loss](https://doi.org/10.5194/tc-15-2383-2021)
- [National Science Foundation (27 Apr 2017). *Ice cave in Transylvania yields window into region's past*: the minimum age of at least 10,500 years, the warm peak 7,000–5,000 years ago, the 2017 plan for 13,000 years](https://www.sciencedaily.com/releases/2017/04/170427130801.htm)

### The cave

- [Scheffel, Wernet (eds., 1980). *Natural Wonders of the World*, Reader's Digest, p. 339, cited second-hand via the encyclopedia article (original not consulted): the old 3,500-year estimate and the historic 75,000 cubic metres](https://en.wikipedia.org/wiki/Sc%C4%83ri%C8%99oara_Cave)
- [Irimuș, Codrea, Costea. *Scărișoara Ice Cave*, Studia UBB Geographia: the 24 m portal, the cave sectors (with values differing from the 2011 ones, see the method note)](https://cloud.elearning.ubbcluj.ro/index.php/subbgeographia/article/download/2979/2867/5651)
- [World Aquatics, *Swimming Pool Certification* (in force since 1 January 2024): Olympic 50 m pools, length, width and minimum depth](https://resources.fina.org/fina/document/2025/11/04/ea5e650d-44a0-4619-a705-c7354a367995/WA-Pool-Certification-Swimming.pdf)

### Research history

- [The “Emil G. Racoviță” Foundation, publication bibliography: *Observations sur la glacière naturelle dite „Ghețarul de la Scărișoara”*, Bull. Soc. Sci. Cluj, III, 1927, pp. 75–108 (the glacier description); *Speologia* (1927) is a separate work](https://racovita-foundation.org/en/pubs.html)
- [Tabacaru, Danielopol. *The remarkable history of the Emil Racoviță Institute of Speleology (1920–2020)*: the 1921–1925 field years, the 1947 team](https://scholarepos.online/article/3978/fulltext.pdf)
- [Kokker, Kemp (2004). *Romania & Moldova*, Lonely Planet, p. 232, cited second-hand via the encyclopedia article (original not consulted): the 1921–1923 variant of the field years](https://en.wikipedia.org/wiki/Sc%C4%83ri%C8%99oara_Cave)
- [Romfilatelia, the biospeleology centenary: the Cluj institute, the first in the world, director 1920–1947](https://romfilatelia.ro/en/100-years-since-the-foundation-of-biospeleology-by-the-romanian-scientist-emil-racovita/)

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An interactive documentary by [Marius Comper](https://mariuscomper.uk/en/) · https://mariuscomper.uk/ghetarul-de-la-scarisoara/en/