Situated high in the Ötztal Alps, near the Austria-Italy border, lies the Weißseespitze glacier, which serves as a scientific time capsule. Over millennia, snow has accumulated, forming ice layers that store critical historical data. As Europe experienced a surge in mining and smelting activities 1,000 years ago, pollutants like arsenic were released into the atmosphere and settled onto the glacier. Additionally, natural elements from past wildfires provide insights into ancient climates.
Scientists warn that the loss of glaciers equates to a loss of vital information. The Weißseespitze glacier has already suffered due to rising temperatures, resulting in the melting of its upper layers, which hold records from the 1600s onward. What’s left is a historical account covering the second to the 17th centuries CE. Alarmingly, 30 percent of the glaciers in the Ötztal Alps could vanish within the next five years.
“It’s really a race against time, because we have this unique opportunity to inspect the memory of this glacier,” said Azzurra Spagnesi, a paleoclimatologist at the University Ca’ Foscari of Venice and lead author of a recent paper that analyzed the record of pollutants preserved in Weißseespitze’s ice.
Consider the Weißseespitze glacier as a layered cake. Each snowfall brings airborne substances that compact into ice over time. To explore this timeline, Spagnesi’s team drilled over 30 feet into the glacier to reach bedrock, extracting a core. The deeper the ice layer in the core, the older the frozen water and its pollutants, creating a “time-cake” of sorts.
Located in Europe’s densely populated center, the Weißseespitze glacier and its neighbors offer more detailed information than ice cores from remote areas like Greenland and Antarctica. “These local glaciers are going to tell you more of what’s going on nearby,” said Paul Bierman, a geoscientist at the University of Vermont, who authored a book on the Greenland Ice Sheet’s history. “So they’re both valuable — they’re just different.”
By examining pollutants in the ice, researchers can infer past atmospheric conditions and global events. For example, in Weißseespitze samples, Spagnesi and her team detected lead from human activities dating back a millennium. “These peaks indicated human activity was already leaving a detectable mark on the atmosphere,” Spagnesi said.
While human-caused pollution has persisted in the Weißseespitze glacier, the ice core also registered spikes of pollution from natural events like volcanic eruptions. Volcanoes emit trace elements such as arsenic and copper, which eventually settle on Earth. Researchers noted increased levels of these metals in the 13th and 16th centuries CE, hinting at significant eruptions.
Spagnesi and her team also identified ancient climate conditions through natural pollution in the core. Around 1000 CE, they found high levels of levoglucosan, a chemical from burning vegetation, which aligned with elevated charcoal levels in samples from nearby peatlands. Both environments, which accumulate year after year, suggest widespread wildfires that left traces of smoke.
The factors causing these ancient fires could be strikingly similar to today’s conditions. The ice and peat signals correspond to a prolonged drought, where episodic rains would promote vegetation growth that would later dry out and fuel wildfires. This mirrors the situation in areas like the American West, where climate change is causing extreme rainfall followed by drought.
This urgency in collecting glacier cores stems from the need to understand past climatic changes to improve current climate models. “We need to pass to modelers precise information about changes in past atmospheric composition, and even environmental variability, to train the models,” Spagnesi said.
However, glaciers like Weißseespitze in the Alps are rapidly shrinking. The 30-foot core extracted by Spagnesi’s team in 2019 reached bedrock, but by 2025, a subsequent core hit the glacier’s bottom after just 18 feet. As the glacier retreats, the historical record moves further back in time, leaving scientists with only ancient data. They are racing to extract more cores while they can.
“Glaciers are not just ice,” Spagnesi remarked. “They are the archives of the Earth’s memory. And when they disappear, we don’t only lose frozen water, we lose irreplaceable knowledge about how our climate system works and how human activity has altered it.”
