Alpine glacier has lost four meters of ice since 2019, and its climate archive is vanishing with it

In 2019, a team of scientists drilled through 9.5 meters of ice at the Weissseespitze glacier near the Austrian-Italian border, reaching bedrock. They pulled up an ice core containing atmospheric particles deposited by snowfall over more than two millennia - a frozen record of air pollution, volcanic eruptions, wildfires, and human activity dating back as far as 349 BCE.

When they returned to the same drilling site in 2025, the ice was only 5.5 meters deep. Four meters of irreplaceable climate archive had melted away in six years.

Lead, arsenic, and the medieval mining boom

The ice core analysis, led by Dr. Azzurra Spagnesi of the University Ca' Foscari of Venice and published in Frontiers in Earth Science, traced 18 different elements along with microcharcoal, levoglucosan (a chemical compound produced when wood burns), and various organic acids through the core's layers.

The team used argon isotope data to date the layers. The glacier's surface formed between roughly 1552 and 1708 CE, while the deepest ice dated to between 349 BCE and 420 CE. Between those boundaries lay a detailed chemical record of how human activity and natural events left their marks on Alpine air quality.

Between 700 and 1200 CE, lead and other metals remained at very low concentrations, reflecting a largely unpolluted pre-industrial environment. But from roughly 950 CE onward, the picture changed. Peaks in arsenic, lead, copper, and silver appeared, corresponding to periods of intensified medieval mining and smelting operations across the Alps and broader Europe.

Some of the strongest metal peaks coincided with known major volcanic eruptions, as well as periods of dry climate and increased dust transport. The overlap means that both natural events and human activities contributed to the chemical signals preserved in the ice - and disentangling the two is not always straightforward.

A century of drought and fire

A particularly striking peak in chemical pollution appeared between approximately 902 and 1280 CE. When the researchers compared this with microcharcoal levels found in peat cores from nearby swampy areas, they found matching peaks - evidence that fires were more frequent and intense during this period.

A roughly century-long drought between about 950 and 1040 CE appears to have been a key driver. Dry conditions promote cycles of vegetation growth followed by desiccation, creating landscapes prone to burning. At the same time, human activity in Alpine regions intensified, with historical evidence pointing to increased grassland management, agricultural expansion, and land clearing - all of which commonly involved fire. Periods of conflict may have contributed through deliberate burning or accidental ignitions.

The researchers caution, however, that dating uncertainties remain relatively large despite the addition of argon-39 dating to complement earlier radiocarbon constraints. Individual chemical peaks cannot always be linked to specific historical events with confidence.

A natural baseline that no longer exists

One finding stands out for its relevance to the present. Anthropogenic emissions accounted for only about 7% of the total air pollution recorded in the ice core. Human-caused pollution appeared as isolated peaks against a comparatively stable natural background - a pattern that bears no resemblance to modern conditions, where human emissions dominate the atmospheric chemistry of the region.

That contrast underscores both the value of these ice archives and the urgency of preserving what remains. Alpine glaciers provide a uniquely detailed record of the transition from pre-industrial to industrial atmospheric conditions, precisely because of their proximity to the human settlements that drove those changes.

The clock is running out

Glaciers in the Otztal Alps - the mountain range that includes Weissseespitze - are projected to disappear within the coming decades. Each year of melting destroys chemical and physical data that took centuries or millennia to accumulate.

Spagnesi was direct about the stakes: if glaciers disappear, the information they contain will be lost permanently, leaving gaps in our understanding of past climate variability. Preserving glaciers, she argued, is not just about protecting ice - it is about safeguarding the memory of Earth's climate.

The research team continues to visit Weissseespitze, but the window for extracting useful data is narrowing rapidly. The four-meter loss between 2019 and 2025 suggests the glacier may have less than a decade of readable ice remaining, though the precise timeline depends on future warming rates and snowfall patterns.

What the ice has already revealed - medieval mining pollution, drought-driven fire regimes, volcanic signatures, and a pre-industrial atmospheric baseline - demonstrates the scientific value of these frozen archives. The question now is how much more can be read before the pages melt away.