ABSTRACT
Scientists seem to agree that global warming is an
ongoing process of increasing significance. One of
its most alarming consequences would be an accel-
erated sea-level rise, so large as to threaten many of
the world’s coasts, lagoons, estuaries and river deltas
in the next century (Intergovernmental Panel on Cli-
mate Change 2001). In many low-lying coastal areas,
the increasing vulnerability to inundation, associated
with sea level rise and subsidence, is accompanied by
a progressive deterioration of natural defences against
flooding, i.e. barrier islands and wetlands. The coast
of Louisiana is a major example, as the lesson of Kat-
rina has clearly shown. A second important example is
Venice. Here, the lagoon environment is threatened by
a morphological degradation displayed by the loss of
a consistent portion of the salt marsh area throughout
the last century (Figure 1). Why has this happened?
