Coastal wetlands at risk: Learning from Venice and New Orleans

Coastal regions have progressively become more vulnerable to intense hydrodynamic and atmospheric events, thus raising important questions about their fate in the century of global warming. A variety of natural and anthropogenic factors have contributed to this fragility: eustacy, isostasy, soil compaction, reduced sediment supply and reduced extension of natural defenses (barrier islands and coastal wetlands). With the aim to emphasize the crucial role played by the intense human manipulation of the environment, we provide a brief overview of the state of knowledge on this extremely complex problem, moving from two cases of special importance: Venice and New Orleans. We discuss similarities (causes of wetland degradation and related restoration problems) as well as differences (different economical scales involved in the restoration projects, different risk reduction ensured by wetland and natural defense restoration and, finally, cultural relevance of the environment to be preserved) between these two regions.