The Atacama Desert in Chile
Photo Credit: © Dr. Benedikt Ritter-Prinz
Scientific Frontline: Extended "At a Glance" Summary: Atacama Desert Hyperaridity
The Core Concept: The hyperarid core of the Atacama Desert in Chile established its extreme dryness approximately 45 million years ago. This establishes it as one of the longest continuously dry terrestrial environments on Earth.
Key Distinction/Mechanism: Unlike temperate regions where precipitation drives continuous erosion and sediment transport, hyperarid regions experience less than two millimeters of annual rainfall. This severe water limitation results in extraordinarily slow surface processes, effectively preserving the landscape over geological timescales.
Origin/History: Previous scientific consensus placed the onset of Atacama Desert aridity in the Early to Mid-Miocene (10 to 20 million years ago). Recent analysis pushes this timeline back by 20 million years, indicating that extreme aridity was established shortly after the global cooling that followed the Early Eocene Climate Optimum (EECO).
Major Frameworks/Components:
- Cosmogenic Nuclide Exposure Dating: An analytical method used to measure rare isotopes (specifically \(^{21}\text{Ne}\) and \(^{10}\text{Be}\)) that accumulate when cosmic rays interact with surface minerals, allowing researchers to quantify undisturbed landscape exposure over tens of millions of years.
- Post-EECO Global Cooling: A climatological model demonstrating that global temperature reductions, rather than localized tectonic events like the Andean uplift, were the primary initiators of reduced moisture availability in the region.
- Earth Evolution at the Dry Limit: A research framework investigating the threshold of planetary habitability by studying how biological activity and geological surface processes co-evolve under severe water scarcity.
Branch of Science: Paleoclimatology, Geochronology, and Geology.
Future Application: The established chronological dataset supports emerging predictive models for species adaptation under changing climates, evolutionary lag times, and the identification of tipping points in Earth surface systems experiencing severe desiccation.
Why It Matters: By securing a 45-million-year benchmark for continuous hyperaridity, scientists acquire an unprecedented natural laboratory to investigate the fundamental interactions between climate, slow geological processes, and biodiversity at the absolute limits of habitability.
A new study provides evidence that extreme aridity in the hyperarid core of the Atacama Desert began approximately 45 million years ago, significantly earlier than previously assumed. The findings refine current models of desert formation and offer new perspectives on the long-term evolution of one of Earth’s most extreme environments.
For decades, scientific consensus placed the onset of Atacama Desert aridity in the early to middle Miocene (approximately 10–20 million years ago). Using a novel and extensive dataset, the research team now shows that hyperarid conditions were already established shortly after the global cooling that followed the Early Eocene Climate Optimum (EECO), approximately 45 million years ago. This pushes the timeline of extreme dryness back by around 20 million years. Published in Nature Communications under the title “Evidence for Eocene aridification of the Atacama Desert’s hyperarid core,” the study was conducted with colleagues from the Scottish Universities Environmental Research Center in Glasgow and Goethe University Frankfurt.
“Our results indicate that today's hyperarid core of the Atacama Desert has been established since the middle to late Eocene, as indicated by extremely low surface activity,” says Dr. Benedikt Ritter-Prinz from the Institute for Geology and Mineralogy at the University of Cologne. “This makes it one of the longest continuously dry regions on Earth and forces us to reconsider how and when such extreme environments develop.”
Unprecedented Evidence from Earth’s Oldest Surface Clasts
The study is based on cosmogenic nuclide exposure dating, a method that measures rare isotopes formed when cosmic rays interact with minerals at Earth’s surface. The team analyzed quartz clasts and quantified concentrations of \(^{21}\text{Ne}\) (and partially \(^{10}\text{Be}\)), which accumulate only while rocks remain exposed to cosmic rays—that is, on Earth's surface.
By examining 135 samples, far more than typical studies, the researchers obtained the highest cosmogenic nuclide concentrations of \(^{21}\text{Ne}\) ever reported. These exceptionally high values indicate that surface clasts in the Atacama have remained largely undisturbed on the surface for tens of millions of years.
“In more temperate regions, precipitation drives erosion and sediment transport, constantly reshaping the landscape,” explains Professor Tibor Dunai of the University of Cologne. “In contrast, the Atacama’s hyperarid core, with less than two millimeters of annual rainfall, shows extraordinarily slow surface processes. The landscape is effectively preserved over geological timescales.”
The findings also provide a revised framework for understanding the mechanisms behind Atacama Desert aridity. While the uplift of the Andes and the influence of the cold Humboldt Current remain important, the study suggests these factors primarily intensified and expanded existing dry conditions rather than initiating them.
Instead, the onset of hyperaridity appears linked to global climate cooling following the EECO, which likely reduced moisture availability in an already semiarid region. Over time, tectonic and oceanographic changes reinforced and extended these conditions, shaping the desert as it exists today.
The study further highlights that aridity evolved unevenly across the region, emphasizing the importance of spatial variability in long-term climate development.
Linking Landscape Evolution, Climate, and Life at the Dry Limit
The research is closely connected to the goals of Collaborative Research Center 1211, “Earth Evolution at the Dry Limit” (CRC1211), at the University of Cologne, which investigates how life and Earth surface processes coevolve under extreme water limitation.
Water is the defining feature of a habitable planet, yet large parts of Earth exist under severe water scarcity. In such environments, both biological activity and surface processes are strongly constrained, and their interactions remain poorly understood. The Atacama Desert, as one of the driest places on Earth, provides a natural laboratory to explore these relationships.
“Our findings establish a robust long-term climatic framework for one of the most water-limited regions on Earth,” says Dr. Benedikt Ritter-Prinz. “This is essential for linking the evolution of landscapes with the evolution and adaptation of life under extreme conditions.”
In arid to hyperarid systems, rare and short-lived increases in water availability can leave lasting imprints on the landscape. These transient events may also influence biological colonization and evolution, although such links are still not fully resolved. By extending the record of hyperaridity back to 45 million years, the study provides a crucial temporal context to investigate how climatic fluctuations, surface processes, and life interact at the limits of habitability.
The results of the recent study contribute to a broader effort to identify thresholds for biological colonization, understand tipping points in Earth surface systems, and reconstruct long-term climate histories in extreme environments. They also support emerging research into evolutionary lag times, species adaptation to changing climates, and the interplay between geological processes and biodiversity.
With its large dataset and record-setting cosmogenic nuclide concentrations, the study establishes a new benchmark for investigating long-term landscape stability and climate evolution.
“This work highlights how extremely slow Earth surface processes can operate over tens of millions of years,” says Dr. Benedikt Ritter-Prinz. “It opens new avenues for understanding the relationships between climate, landscapes, and life in the most extreme environments on our planet.”
Published in journal: Nature Communications
Title: Evidence for Eocene aridification of the Atacama Desert’s hyperarid core
Authors: Benedikt Ritter-Prinz, Steven A. Binnie, Finlay M. Stuart, Derek Fabel, Richard Albert, Volker Wennrich, and Tibor J. Dunai
Source/Credit: University of Cologne
Edited by: Scientific Frontline
Reference Number: es060626_01
