The synchronization of data from two natural climate archives—a speleothem from the Herbstlabyrinth Cave in Hesse (Germany) and ice cores from Greenland—has provided groundbreaking insights into the chronology of abrupt climate changes in Central Europe. This new research has not only refined the dating of the Laacher See volcanic eruption but also shed light on the climatic effects of this event, altering previously held assumptions about its connection to the Younger Dryas, a significant cold period that occurred approximately 13,000 years ago.
New Findings Challenge Previous Assumptions
The Laacher See volcano, located in modern-day Rhineland-Palatinate, Germany, is considered one of the most catastrophic eruptions in the past two million years. Its effects were widespread, with the volcanic ash and aerosols reaching regions as far as northern Italy, Scandinavia, and Russia. However, the timing of this eruption and its potential connection to the Younger Dryas—a period of sudden and severe cooling—has long been a subject of intense scientific debate.
Until recently, it was widely assumed that the eruption of Laacher See played a crucial role in triggering the abrupt climate shift of the Younger Dryas. However, recent research led by geoscientists from Heidelberg University and Mainz University, published in Science Advances, presents a revised temporal classification of the eruption. By synchronizing geochemical data from a speleothem in the Herbstlabyrinth Cave with ice core samples from Greenland, the researchers discovered that the Laacher See eruption occurred significantly earlier than previously thought—by approximately 130 years.
This new timing, based on radiocarbon dating of tree trunks carried out in 2021, suggests that the volcanic event predated the Younger Dryas by over a century. As a result, the eruption could not have directly triggered the sudden onset of this cold period, as earlier theories proposed.
Methodology: Analyzing Sulfur Signals
The research team from Heidelberg and Mainz used a speleothem—an underground formation made of mineral deposits from dripping water—collected from the Herbstlabyrinth Cave in Breitscheid, Hesse, to confirm the revised eruption date. Speleothems serve as valuable natural archives, preserving information about past climate conditions through the chemical composition of their layers. The team analyzed sulfur and oxygen isotope ratios within the speleothem to identify volcanic signals associated with the eruption.
Volcanic eruptions release large amounts of sulfur dioxide (SO₂) into the atmosphere, which can then react with water vapor to form sulfate aerosols. These sulfate particles are deposited in ice cores, as well as in other climate archives like speleothems. By analyzing sulfur isotopes at a high resolution, the team was able to detect a volcanic signal in the speleothem corresponding to the Laacher See eruption. Using an ion probe at Heidelberg University, the researchers measured isotope ratios and trace elements at micrometer-scale precision, a technique that allowed them to pinpoint the exact timing of the eruption.
This sulfur signal in the speleothem was then synchronized with a sulfate peak found in Greenland ice cores. These ice cores are one of the most important sources of information for reconstructing past climate changes, as they preserve a detailed record of atmospheric conditions going back thousands of years. The synchronization of these two archives—the speleothem and ice cores—enabled the researchers to establish a more accurate timeline of the Laacher See eruption.
Implications for the Younger Dryas and Climate Change
One of the most significant aspects of this research is its impact on the understanding of the Younger Dryas. For many years, the eruption of Laacher See was thought to have caused a dramatic shift in the Earth’s climate, initiating the abrupt cooling associated with the Younger Dryas. However, the new research has confirmed that the eruption occurred long before the onset of this cold period, thus ruling out a direct causal link between the two events.
Dr. Sophie Warken, the first author of the study and a researcher at Heidelberg University, explained that the new dating shows the eruption occurred about 150 years prior to the start of the Younger Dryas. This challenges the previous hypothesis that the volcanic event triggered the sudden temperature drop that marked the cold period. “This therefore excludes a causal relationship between the volcanic eruption and the abrupt change in climate,” Dr. Warken stated.
The findings also shed light on the nature of the climatic events that occurred at the start of the Younger Dryas. By identifying the sulfur spikes in the Greenland ice cores, the team was able to draw conclusions about the timing and extent of the temperature drop. Their research indicates that a significant cooling event occurred simultaneously in both Central Europe and the Arctic, pointing to a direct link between the climates of these two regions.
Methodological Breakthrough
The synchronization of the speleothem and ice core data represents a major breakthrough in the field of paleoclimatology. Prior to this study, there was no known time marker before the Younger Dryas that was absolutely dated, meaning that researchers lacked a precise chronological framework for studying climate events in the millennia preceding this cold period.
Dr. Denis Scholz, a leading expert in age determination of historical climate fluctuations at the Institute for Geosciences at Mainz University, emphasized the significance of the team’s work. “This synchronization represents a breakthrough for the dating of climate and environmental archives, in that, until now, no absolutely dated time marker before the Younger Dryas cooling was known,” he explained. By establishing a precise timeline for the Laacher See eruption, the researchers have created a new reference point for understanding past climate changes.
Understanding Complex Climatic Relationships
The study’s results also have important implications for how we understand the complex interplay between different climatic regions. Previous research had struggled to determine whether the climatic changes associated with the Younger Dryas occurred simultaneously across the North Atlantic and Central Europe or whether the cooling spread gradually from one region to the other over several decades or centuries.
With this new evidence, the researchers suggest that the cooling during the Younger Dryas was synchronous, with both the Central European and Arctic climates experiencing a rapid temperature drop at the same time. “Our results lead to the conclusion that a significant drop in temperature occurred simultaneously, indicating that the Central European and Arctic climates were directly linked,” Dr. Warken explained.
This new understanding of the Younger Dryas and its timing is crucial for improving our models of past climate behavior. By refining our understanding of how abrupt climate shifts occurred in the past, scientists can make more accurate predictions about future climate trends, particularly in the context of global warming and the potential for sudden shifts in temperature.
Broader Impact on Climate Research
The findings of this study also have broader implications for future climate research. By establishing a more accurate timeline for key climate events like the Laacher See eruption and the Younger Dryas, scientists can improve their understanding of the causes and consequences of abrupt climate changes. These insights could help inform climate models, which are essential for predicting future shifts in global temperatures, sea levels, and atmospheric conditions.
Furthermore, the ability to synchronize data from multiple natural archives—such as speleothems and ice cores—provides a powerful tool for reconstructing past climate history with greater precision. This methodological approach could be applied to other key climate events, allowing researchers to build more comprehensive and reliable records of Earth’s climatic history.
Conclusion
In summary, the new research conducted by Heidelberg University and Mainz University represents a significant advancement in our understanding of the Laacher See eruption and its climatic effects. By synchronizing data from a speleothem in Germany and ice cores from Greenland, the team was able to refine the eruption’s timing and rule out its direct connection to the Younger Dryas. The findings provide crucial insights into the relationship between the Arctic and Central European climates and offer a new reference point for dating ancient climate events.
These results not only challenge existing hypotheses but also open up new avenues for future research into the complex dynamics of past climate fluctuations. By improving our understanding of these shifts, scientists are better equipped to predict future climate trends and assess the potential impacts of global warming.
Reference: Sophie F. Warken et al, Discovery of Laacher See eruption in speleothem record synchronizes Greenland and central European Late Glacial climate change, Science Advances (2025). DOI: 10.1126/sciadv.adt4057