Roman and Early Medieval palisades discovered in Grado provide insights into historical sea-level changes and local paleoenvironment

The scientific community has devoted significant resources to studying the relative rise in sea level, a direct consequence of global warming, due to its status as one of the most alarming environmental threats worldwide.

Coastal regions are recognised as being amongst the most vulnerable areas in terms of climate change impacts. According to official reports from ISPRA, around 30% of the Italian population lives in such areas. Projections for the least critical climate scenario indicate that sea levels could rise by approximately 0.5 meters by the year 2100, which poses significant risks to landscapes, infrastructure, and coastal settlements.

In the past, variations in sea levels had a significant impact on the occupation of coastal areas. Sometimes populations were compelled to abandon sites that were threatened by flooding. At other times, they implemented engineering remedies to combat water ingress and preserve the habitability of the territory. This is exemplified by the case of Grado, in Friuli Venezia Giulia.

A new study, published in the journal Scientific Reports, coordinated by Dario Gaddi of Archeotest s.r.l., and involving scholars and researchers from the National Institute of Oceanography and Applied Geophysics (OGS), the Department of Physics and Astronomy "Augusto Righi" of the University of Bologna, the National Institute of Geophysics and Volcanology (INGV), and the Superintendence of Archaeology, Fine Arts and Landscape for Friuli Venezia Giulia, has revealed in Grado three palisades of Roman and Early Medieval age, dating back to a period between the 1st and 6th centuries CE.

The oldest palisade (1st–2nd century CE) was likely built as a containment barrier for reclamation material dumped from the mainland. Another similar structure, dated via dendrochronology to 566 CE, has been interpreted as an attempt to counteract the effects of rising sea levels.  A third barrier, of a similar age to the previous one and of which only three planks were recovered, was arguably erected not to mitigate marine ingress but rather to consolidate the Castrum.

The multidisciplinary analysis of all these structures, which in ancient times also served a protective function against coastal erosion, has made it possible to reconstruct both the evolution of the depositional environment of the Grado area (a process which has also been influenced by numerous human interventions) and changes in relative sea level along the northeastern Adriatic coast.