Fungi are among the most successful organisms on Earth, dispersing billions of microscopic spores through the atmosphere. While their presence near the Earth's surface is well documented, almost nothing is known about their occurrence in the stratosphere, an extreme environment characterized by intense UV radiation, prolonged desiccation, and temperatures reaching −63°C.

Recent evidence suggests that some fungal spores may survive these conditions, raising fundamental questions about their resilience and their capacity for long-distance dispersal. To explore this hidden dimension of the biosphere, we will investigate the diversity, abundance, and viability of fungal spores between 12 and 35 km altitude using balloon-borne sampling systems combined with cultivation, molecular analyses, and environmental DNA metabarcoding.

By characterizing both resident and newly injected spores following wildfires and volcanic eruptions, this project will provide the first comprehensive assessment of fungal life in the stratosphere and its potential role in the global dissemination of plant pathogens in a changing climate.