(Image: Robbie Shone/National Geographic Creative)

Going…going… thousands of years of frozen history will be gone in a matter of decades. The hole in the centre of this ice-filled cave in central Austria is growing quickly, swollen by the warming climate. With the melting ice, unique climate records are trickling away – before we can figure out how to interpret them properly.

The ice in these deposits is special because it promises to unlock secrets about past climate other natural archives won’t easily relinquish.

Unlike ice cores – which offer incredibly detailed and ancient records of the climate – the cave ice could spill the beans on more recent atmospheric conditions in heavily inhabited areas, says Marc Luetscher from the University of Innsbruck, who is working on the ice. What’s more, the ice would neatly complement tree-ring records. Trees grow faster during warm weather, so give good information about climatic conditions in summer. The ice in the caves forms during cold weather, telling us what winters were like.


Luetscher says that to interpret the data, they need to figure out exactly how the ice hung around despite historic mean annual temperatures that were frequently above 0 °C.

The rare large ice crystals in the picture below –which come from a nearby cave – might offer some clues, says Leutscher, because they grew very slowly and so preserve a precise record of temperature fluctuations in the region.

This article appeared in print under the headline “Melting moments”