When the city of Venice installed flood barriers across the mouths of its lagoon in 2020 — a project decades in the making and costing several billion euros — it accomplished something that was, by any reasonable measure, a triumph of engineering. The barriers, known collectively as MOSE, were designed to protect the city from the acqua alta, the periodic tidal surges that had been inundating the historic centre with increasing frequency and severity. Their successful activation was greeted with celebrations that bordered on the euphoric, and for good reason: Venice, the most celebrated built environment on earth, had been given a reprieve from the sea that had been threatening, with gathering urgency, to reclaim it.
Yet within the jubilation there lurked a disquiet that few were willing to articulate publicly but that has since become impossible to ignore. The barriers protect Venice from the water, but they do so by severing, at intervals of increasing frequency, the connection between the city and the lagoon ecosystem upon which its existence has always depended. The lagoon is not merely a scenic backdrop to the city; it is the medium through which Venice breathes — the tidal exchange that flushes its canals, sustains its fisheries, and maintains the delicate chemical equilibrium of the waters upon which its foundations rest. Every closure of the barriers interrupts this exchange, and as sea levels continue to rise and closures become more frequent, the cumulative ecological consequences threaten to transform the lagoon from a living estuarine system into a stagnant basin, with implications for water quality, biodiversity, and ultimately the structural integrity of the very buildings the barriers were designed to protect.
The Venice dilemma is a particularly vivid instance of a broader paradox that confronts the conservation of historic environments worldwide: the measures undertaken to preserve a place from one threat frequently generate new threats that are, in the long run, no less destructive than the original. The cathedral that is enclosed in scaffolding to prevent the erosion of its façade is simultaneously deprived of the ventilation that prevents moisture from accumulating within its walls. The archaeological site that is roofed to protect its mosaics from rain is simultaneously subjected to the temperature fluctuations and condensation that the roof itself creates. In each case, the intervention addresses the immediate danger while introducing secondary effects that may, over decades, prove equally damaging.
The root of the paradox lies in a conception of preservation that treats the historic object as a static entity to be maintained in a fixed state, rather than as a dynamic system embedded in, and continuously shaped by, the environmental processes from which it emerged. A Venetian palazzo is not an artefact that happens to be located beside water; it is a structure that was designed to coexist with water, whose materials, construction techniques, and spatial organisation presuppose a particular hydrological regime. To alter that regime — even with the benign intention of protecting the building — is to change the conditions under which the building functions, and therefore, in a sense that is more than merely metaphorical, to change the building itself.
The philosopher of conservation Salvador Herrera Gonzalez has argued that the traditional paradigm of preservation — which he calls the 'classical theory' — rests upon a fundamental misunderstanding of the relationship between an object and its environment. The classical theory treats deterioration as an extrinsic imposition upon an object whose 'true' state is one of pristine completion. Herrera Gonzalez contends, persuasively, that this is an illusion: all material objects are in a continuous process of transformation, and what we call deterioration is simply the name we give to transformations we do not like. Preservation, on this account, is not the arrest of change but the management of change — a negotiation between the trajectories we wish to encourage and those we wish to retard, conducted in full awareness that the distinction between the two is a matter of human judgement rather than objective fact.
This reconceptualisation does not solve the practical problems of conservation, but it does something equally important: it forces us to acknowledge that every act of preservation is also, inevitably, an act of transformation, and that the question we must ask is not whether to intervene but how to intervene in ways that respect the complexity of the systems we are trying to protect.