Between 2000 and 2020, researchers documented temperature increases in four Alpine caves, showing a rise of approximately 0.2 °C per decade. This rate is half that of the surface temperatures observed across Europe. This subtle yet consistent warming in Alpine caves lags behind surface warming, signaling that atmospheric temperature changes are reaching deep into the earth’s interior. Such subsurface warming shows remarkable spatial consistency, affirming a direct link to broader climate changes affecting the Alps.
The warming trend affects more than just temperature. Caves like Spannagelhöhle and Schrattenhöhle exhibit shifting airflows and altered hydrology, which disrupts delicate subterranean ecosystems. Stalactites, stalagmites, and even karst hydrology—key elements of cave environments—are vulnerable to these changes. In particular, the warming trend threatens to melt perennial ice deposits in some caves, paralleling the retreat of surface glaciers and the melting of permafrost observed throughout the Alps. This loss could occur within the next decade, eliminating a vital reservoir supporting downstream ecosystems during dry periods.
The research highlights that caves with restricted ventilation retain colder temperatures, creating “cold traps” that preserve ice longer. In contrast, well-ventilated caves like Schrattenhöhle display greater temperature fluctuations, especially near entrances. This “chimney effect,” driven by seasonal airflows, accelerates warming and affects the stability of ice near cave openings.
The Alps are warming twice as fast as the global average. Alpine streams, lakes, and groundwater have shown similar warming trends, with outside temperatures near caves rising at approximately 0.5 °C per decade. As cave temperatures continue to rise, increased cave ventilation, ice melt, and potential habitat loss could further impact regional hydrology and biodiversity.
The study underscores the need for continuous monitoring of Alpine caves. As natural climate archives, caves offer valuable data to help track climate change impacts and inform broader environmental strategies. Comprehensive research on subterranean ecosystems, climate modeling, and data collection will be essential for understanding and mitigating the impact of warming trends on these unique environments.
