A previously unknown and extraordinary glacial melt event dating back to the Medieval Warm Period has left striking evidence on a glacier in Northern Victoria Land, Antarctica. The discovery is detailed in an international study published in the prestigious journal Communications Earth and Environment, titled "A warming pulse in the Antarctic continent changed the landscape during the Middle Ages." For the first time, the study reconstructs the impact of a sudden climatic warming that occurred between 900 and 989 years ago and significantly altered the Antarctic landscape.

The research, coordinated by Emanuele Forte (University of Trieste) and Mauro Guglielmin (University of Insubria and Centre for Climate Change Research), in collaboration with Maurizio Azzaro (Institute of Polar Sciences of the National Research Council – CNR-ISP), Nicoletta Cannone and Alessandro Longhi (University of Insubria and Centre for Climate Change Research), and Ilaria Santin (ETH Zurich), documents a phenomenon never before observed. The study identifies intense fluvial erosion and sediment transport across the glacier’s surface, caused by meltwater runoff that carved a channel at least four kilometres in length.

The findings show that the water left a lasting imprint on the glacier, creating a break in the stratigraphy and forming a graded sediment deposit – clear evidence of a gradual slowing of the water flow. Unlike current melt events observed in East Antarctica and on the Nansen Ice Shelf, the medieval event stands out as an exceptional case. It occurred during a naturally occurring phase of global warming, yet the same glacier today remains permanently snow-covered with no signs of surface melting. This contrast further highlights the uniqueness and significance of the discovery.

The research offers a new perspective on the stability of Antarctic glaciers and demonstrates that even short-lived episodes of climatic warming – often undetectable through traditional palaeoclimatic analysis – can lead to profound and lasting changes in glacial landscapes. The results underscore the sensitivity of Antarctic glaciers to sudden climate shifts and point to the potential impact of extreme events linked to ongoing climate change.

The study was conducted as part of the National Antarctic Research Programme (PNRA), funded by the Ministry of Universities and Research (MUR) and implemented through the National Research Council (CNR) for scientific coordination, ENEA for the planning and logistical support of activities at Antarctic bases, and the National Institute of Oceanography and Applied Geophysics (OGS) for the technical and scientific management of the research vessel Laura Bassi.