Glacial ice offers a detailed record of the atmosphere, preserved in discrete layers, providing researchers with a valuable tool for studying human history. A sample taken from a glacier in the European Alps dates back at least 12,000 years, making it the oldest ice yet recovered in the region.
Studies of glacial ice in Europe have revealed a surge in lead pollution at the height of the Roman Empire and a drop in pollen from when farming collapsed during the Black Death. Oxygen and hydrogen isotopes trapped in ice provide a record of past temperature, allowing scientists to document past climate change.
An ice core taken from Dôme du Goûter in France extends the glacial record back before the dawn of human civilization. “You have humans going from hunter-gatherers with a very low population through the development of agriculture, domestication of animals, mining,” said coauthor Joe McConnell, of the Desert Research Institute in Nevada. “And it’s right in the center of Europe — where much of Western civilization evolved.”
Taken in 1999, the 130-foot core sat in a freezer in France for more than 20 years before scientists brought it to the Desert Research Institute, where they were able to use specialized equipment to melt down the ice and study its chemistry layer by layer. The ice showed summer temperatures in the Alps were around 3.5 degrees C (6.3 degrees F) cooler before the end of the last ice age.
The ice also showed a spike in phosphorus, from vegetation, which coincided with the spread of forests, and a decline in phosphorus as humans cleared woods to plant farms and build cities. The findings were published in PNAS Nexus.
Further study of the ice core may reveal more of the human story, McConnell said. “Now we can start to interpret all these other records that we have of lead and arsenic and other things like that, in terms of human history.”
Such research has taken on new urgency with climate change. As warming intensifies, scientists are rushing to gather ice from endangered glaciers before they disappear.
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