AILSA CHANG, HOST:
If you want to learn more about human history, you can turn to written records or archaeological artifacts or huge chunks of ice. That's right. Glaciers and other kinds of ice can store clues that reveal the past activities of people who lived nearby. NPR's Nell Greenfieldboyce reports on what researchers recently found when they looked at one icy spot in Europe.
NELL GREENFIELDBOYCE, BYLINE: The Alps Mountain range stretches across Europe. In the eastern part, there's the Weiseespitze (ph) summit ice cap. It looks like an expanse of ice covering one flat mountain. Andrea Fisher is a glaciologist at the Austrian Academy of Sciences. She's part of a team that drilled ice from this place about six years ago when the ice cap was around 10 meters thick. Since then, because of warming temperatures, half of it has melted away.
ANDREA FISHER: Now we have only 5 meters left, and these 5 meters will be gone in the next years.
GREENFIELDBOYCE: The ice cores they drilled out are shaped like cylinders, and they're made up of layers. These ice layers were created by falling snow that got deposited over time. So they're kind of like rings in a tree in that they hold a record of past events. The chemistry of the ice layers can be analyzed in the lab.
FISHER: The first thing they learned, which I consider is very important, is that the ice up there had lasted for 6,000 years.
GREENFIELDBOYCE: The layer of ice on the surface turned out to be from around the 17th century with deeper layers going further and further back in time. Over these thousands of years, people had been living in this region, and pollution from their pre-industrial activities traveled through the air and got frozen inside of the ice. For example, the researchers found chemical signs that correlate with increased mining of metals during medieval times, like arsenic, lead, copper and silver. The ice also contained a spike in pollution from frequent fires that burned across the landscape around the 10th century, which could have been related to increased clearing of land for farming. A report on their recent findings appears in the journal Frontiers In Earth Science. Alison Criscitiello found it really compelling.
ALISON CRISCITIELLO: It just kind of paints this general picture of what was going on during this time period.
GREENFIELDBOYCE: She's an ice core scientist with the University of Alberta who wasn't part of this research team. She says, beyond the clues about human history found in the ice, what fascinated her was that this study focused on a kind ice that scientists can sometimes overlook.
CRISCITIELLO: This record came from an area that is disappearing in real time. It is actively being lost.
GREENFIELDBOYCE: That's why the ice layers that formed during the most recent centuries, the Industrial era, were already gone when the researchers showed up to drill and why so much more of the ice on the mountain has been lost since then. She says, typically, when scientists think about where to prioritize drilling cores of ice so that these samples can be preserved as the climate changes...
CRISCITIELLO: We are specifically looking for the opposite of this, right? We're looking for places that probably will see warming, you know, in the next decade or several decades. So they're places of priority and urgency right now, but oftentimes, places that have not yet seen melt.
GREENFIELDBOYCE: She says this study shows that even ice that's experiencing drastic melting can be a treasure trove. It makes her wonder what other places are out there like this being overlooked as the history trapped inside of them steadily melts away Nell Greenfieldboyce, NPR News. Transcript provided by NPR, Copyright NPR.
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