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Digging into glacier ice to understand antibiotic resistance
Why drill glaciers to study a global health threat ?
Microorganisms are at the heart of Earth’s ecosystems. But over centuries, human activities—especially the use of heavy metals (like mercury, copper, and arsenic) and antibiotics—have deeply disturbed microbial communities.
Recent studies show that genes conferring resistance to metals and antibiotics are often found together, on mobile pieces of DNA that microbes can easily share. This means that even in the absence of antibiotics, pollution with heavy metals can indirectly maintain antibiotic resistance in microbial populations.
Understanding how and when this co-selection emerged is key to developing better environmental and public health policies. That’s where Paleo-MARE comes in : by analyzing natural archives—like glacier ice and sediment cores—the project seeks to uncover the long-term history of pollution and microbial adaptation.
How do we drill ice to uncover the past ?
In May 2025, the Paleo-MARE team achieved a key milestone : successfully drilling an ice core from Col du Dôme, on Mont Blanc. This site, chosen for its long-standing record of atmospheric pollution from across Europe, offers a unique opportunity to trace human impact back centuries.
The field mission brought together ten people, including scientists, engineers, technicians, and early-career researchers. Using the Clos de l’Ours station and the Vallot hut as bases, the team transported equipment by helicopter, set up a clean drilling site, and used an electromechanical drill (a type of drill that minimizes contamination) to extract layers of ice—each one holding valuable chemical and microbial traces from the past.
Everything had to be carefully coordinated : setting up in high alpine conditions, ensuring team safety, handling and labeling samples, preserving the cold chain for transport… all to ensure the ice arrived intact for lab analysis.
Who makes this kind of science possible ?
A mission like this relies on a wide range of expertise :
- Glaciologists and geophysicists, to select drilling sites and interpret environmental signals (with major contributions from the CryoDyn and ICE3 groups at IGE as well as the F2G platform.
- Field engineers and technicians, skilled in operating drills and ensuring clean sample collection.
- Microbiologists, geochemists and bioinformaticians, who will process and analyze the samples using the PANDA platform at IGE.
- Environmental health researchers, to link findings to real-world health risks.
- And a dedicated team of early-career scientists and PhD students, involved in both fieldwork and lab analysis.
What’s next ?
The ice cores are now safely stored and ready for in-depth analysis. Using cutting-edge techniques such as metagenomics (sequencing of the DNA), metabolomics (chemical composition), and high-resolution geochemistry, researchers aim to reconstruct how microbial communities have responded to centuries of metal exposure—from the Roman Empire to the industrial era.
This work bridges paleoecology and public health, helping us anticipate how future pollution and climate change might accelerate the global spread of antibiotic resistance—a crisis already causing 700,000 deaths per year, and projected to reach 10 million by 2050.
Author and scientific contact : Catherine Larose (CNRS)
Editing : Anne Chapuis (CNRS)
Paleo-MARE has received funding from the European Research Council (ERC) under the European Union’s Horizon Europe research and innovation programme (grant agreement No. 101088091)
Updated on 30 septembre 2025