Andrea Fischer
Glaciers in the Ötztal Alps in Austria are currently melting and may be lost within two decades, but this might not be the first time humans have seen this kind of change. A new analysis reveals that glaciers in this region formed just before or perhaps even within the lifetime of Ötzi the Iceman, a mummified body found just 12 kilometres away in 1991.
Pascal Bohleber at the Austrian Academy of Sciences in Vienna and his colleagues drilled 11 metres into the Weißseespitze summit glacier, down to the bedrock, at 3500 metres altitude and collected two ice cores. They then used radiocarbon dating to analyse microscopic bits of organic material extracted from the ice cores and found that the glacier is 5200 to 6600 years old. Ötzi is thought to have lived between 5100 and 5300 years ago, and his body was found preserved in ice.
The glacier’s age means it formed during a time called the mid-Holocene warm period, when Earth’s climate was warmer than it is now. It is also dome-shaped, which Bohleber says is rare in the Alps and means that the ice has seen very little movement over time, meaning we can use it to study the climate when it formed.
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“More information on the mid-Holocene warm period, when the glaciers were smaller than today, is direly needed so that we can better predict how the glaciers will respond to the anticipated future climate over the next 50 years,” says Bethan Davies at Royal Holloway, University of London.
Comparing ice cores from different sites tells us quite a bit about the past climate in that region, says Bohleber, but that gets harder as the glaciers thaw. Meltwater makes it more difficult to drill for ice cores and causes the glaciers to slide downhill, exposing the ancient ice to modern contaminants.
“That can erase these climate archives even before the glacier itself is gone. We just discovered this site and demonstrated its value and I feel that we don’t have a lot of time left to get more of the ice before this record will be gone forever,” says Bohleber.
“This area has been ice-free in the past and if it becomes ice-free in the future, it won’t be the first time. But the rate at which the glacier is melting is unprecedented,” says Davies.
Journal reference: Nature, DOI: 10.1038/s41598-020-77518-9
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