Since the discovery of his frozen body at the base of a shrinking glacier in the Ötztal Alps in 1991, much has been learned about Ötzi, the Copper Age mummy. We know what his last meal was, where he travelled to, how he died, and even that he has living relatives in Austria. Now, thanks to new research, we have a better idea of what the mountains he inhabited looked like around the time he was alive — over 5,500 years ago.
The authors of a paper published in Nature in December used an innovative technique to analyze the Weißseespitze glacier, less than 20 kilometers from the site where Ötzi was found. At this site, scientists were able to reconstruct what the summits of the Ötztal Alps, near the border between Austria and Italy, might have looked like thousands of years ago. They found evidence that the summits of these mountains have been covered in glaciers since approximately 3,880 BCE — about 5,900 years ago and around four hundred years before Otzi died at the end of an enemy’s arrow. The research shows that only the highest peaks remained glaciated throughout the Holocene, the geologic time period that represents the last 11,700 years.
The research site was an ice dome at Weißseespitze, in Austria, that had not been previously explored. “At Weißseespitze we found an almost ideal case,” said lead author Pascal Bohleber in an interview with GlacierHub. “Due to its dome-shaped geometry there is minimal to no ice flow at the ice divide.” An ice divide is a boundary on a glacier between two regions of opposing flow directions, and the preferred location from which to take an ice core. While most glaciers flow down mountains, glaciers at the top of broad summits form relatively stable domes. This geometry and resulting lack of ice flow allowed the oldest ice in the glacier to remain preserved at its base.
Once the scientists realized the great potential of the site at Weißseespitze, they drilled two large ice cores. Then, they used a new technology to date the samples they had taken. “We used state-of-the-art micro-radiocarbon ice dating developed at Prof. Schwikowski’s laboratory in Switzerland,” said Bohleber. “This technique uses the minimal amount of organic carbon that can be found in the ice, even in absence of any macroscopic organic fragments that you could see by eye. An even smaller fraction of this carbon is 14C, radiocarbon, which can be used to determine the age of the ice sample.”
Using these ice samples and dating, the scientists were able to determine what the ice cover in the area might have looked like during Ötzi’s lifetime. “Our new site [at] Weißseespitze is very close to the site where the Tyrolean Iceman was found,” said Bohleber. “Our findings show that the maximum age of Weißseespitze of about 5900 +/- 700 years ago is very close and likely just a bit older than the age of the Iceman. This suggests that in this region and during the lifetime of the Iceman, high Alpine summits were emerging from nearly ice-free conditions.”
There has been significant research about glacial maxima in the Alps. There is much less data available about glacial minima in this region, making this discovery particularly important. Studying historical glacial minima is crucial, because today the Earth is experiencing significant glacier loss. The paper’s authors believe that reconstructing past glacial dynamics in the Alps and their relationship to climate will help guide the understanding of our current deglaciation situation.
“The results provide additional context for the change in ice cover that we see today,” said Bohleber. “Although the current deglaciation of the summits during the Holocene may not be unprecedented, the pace may be. This is a topic on which we urgently need extensive empirical information.”
Ötzi has been capturing the world’s imagination since his discovery. Now, 30 years later, he is helping bring awareness to important climate research which can shed light on our current climate circumstances.
Bohleber and her team hope to continue studying glacial minima in the region. Time for this work, however, is running out. “Current melt rates threaten the extinction of ice archives such as Weißseespitze glacier, which has accumulated over nearly 6,000 years and may now disappear within just decades,” said Bohleber. “We do not have much time to do this.”
