The Attacking Ocean (16 page)

Today the city extends over 117 small islands in the marshy Venetian lagoon along the Adriatic Sea, the lagoon extending along the coast between the mouth of the Po River in the south and the Piave River in the north. Venice’s buildings stand on closely spaced, water-resistant alder woodpiles, many of them originally from Croatia. Most are still intact after centuries underwater, petrified by the constant flow of mineral-rich water that turns them into stone-like structures. They penetrate a layer of soft sand and mud before resting on hard clay. Even at low water, modern Venice is only just above the level of the Adriatic in high medieval times.

Venice oozes romance with its narrow canals and streets, gondolas,
and magnificent palaces and bridges. But now it is also sinking, thanks to a combination of both rising sea levels (twenty-five centimeters over the past century alone) and subsidence caused by shifting tectonic plates and people drawing down groundwater. Not that the threat of floods is anything new, for flood tides push in from the Adriatic every year between fall and early spring, when storm surges generated by winter gales cause water to inundate much of the city. Six hundred years ago, the Venetians protected themselves from attacks from the mainland by diverting all the major rivers flowing into the lagoon. This draconian measure prevented silt from accumulating in the lagoon and filling in the shallows that protected the city, but made them more vulnerable to rising sea levels. Infrequent floods were just part of life during the winter months until the early twentieth century, when local industry began using artesian wells to extract water from subterranean aquifers for its water supplies. The city sank closer to sea level in response as subsidence intensified as a result at a time of rising sea levels. By 1996, ninety-nine floods inundated St. Mark’s Square annually.

The great flood of November 4, 1966, caused by a record high tide behind a sirocco (southerly) wind, inundated the entire city. The waters lingered and caused much-publicized damage to priceless artworks. This was a wake-up call that led to long-term planning for protective measures. Well digging was banned during the 1960s, but the floods are still becoming more frequent, also often higher, inundating the ground floor levels of the city’s buildings. Some studies claim the city is no longer sinking, but the economic stakes are enormous. Venice is now one of the major tourist destinations in the world, to the point that the magnificent city has become a glorified form of tourist theme park, with many fewer permanent inhabitants than in earlier times.

Since 1987, the authorities have embarked on an ambitious long-term project to safeguard the city and its lagoon. The MOSE Project (Modulo Sperimentale Elettromeccanico, or Experimental Electromechanical Module) is an ambitious attempt to check not only natural floods caused by strong winds that push waves into the Gulf of Venice, but also to slow erosion caused by the building of quays and other humanly built structures, as well as by the wakes of passing ships.
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Figure 6.4
St. Mark’s Square, Venice, during a high tide. Author’s collection.

The heart of this hideously expensive project is a system of seventy-eight mobile barriers designed to protect the three major entrances to the Venice Lagoon. The system consists of retracting, oscillating buoyancy flap gates that are designed not to interfere with the natural water exchange between the sea and the lagoon. The conditions surrounding the design are rigorous and include provisions that the barriers not impede fishing or navigation. The gates, which are large metal boxlike structures filled with seawater, normally lie on the bottom, supported by hundreds of concrete pillars. When a tide higher than 110 centimeters is forecast, the boxes are emptied using compressed air and rise, rotating around their hinges until they rise clear of the water. The gates then separate the lagoon from the tide within a space of about thirty minutes. The barriers comprise rows of gates, so that the operators have numerous combinations that can be used to accommodate different conditions. Locks, still currently under construction, will allow ships to pass through, one for larger vessels and two for small ones.

Seemingly monolithic and relatively inflexible, MOSE has been widely criticized by environmental groups, both on account of its expense and of the ecological effects it will have on the lagoon and marine life. For example, if the barriers remain up for some time, as seems likely in an era of more frequent inundations, then there is bound to be pollution in the now-nontidal water. The controversies surrounding MOSE have echoed through local and national politics for years, as well as involving the European Union, which considered the project to have serious polluting consequences for the lagoon.

Apart from these controversies, there remains a fundamental question. Will MOSE save Venice from ultimate submergence, given that St. Mark’s Square is now underwater about a third of the time, as opposed to only seven times in the year 1900? The answer is surely no, for eventually flooding will reach an intolerable frequency and level a few decades from today, even if the barriers are in place. I can speak from personal experience. Carrying one’s airline bags from the hotel to the ferry at the height of a Venice flood is a memorable experience, especially when hordes of aggressive tourists vie to dislodge you into the knee-deep inundation in St. Mark’s Square. Such was my recent experience during a February high tide—not a record level, but one that lapped the foundations of the Doge’s Palace and flooded the narrow streets. The high floods continue. In November 2012, 70 percent of Venice disappeared under floodwaters following a high tide and severe storm with heavy rainfall. High water in the city reached 149 centimeters, the sixth highest since 1872 and the fourth record flood since 2000. Tourists swam in St. Mark’s Square. The authorities attributed the inundation to “global warming.”

The water in the lagoon is rising about two millimeters a year, but recent studies had suggested that Venice had stabilized, that subsidence was no longer a problem. However, a new study by American and Italian researchers using GPS and space-borne radar measurements has documented a subsidence rate of about one to two millimeters annually between 2000 and 2010, probably caused by natural factors such as plate tectonics, which may be compacting the sediments under the city, rather than human activity. The islands in the lagoon are also subsiding at about the same rate or slightly faster. At the same time, the city is tilting
very slightly to the east. If this research is confirmed, then the authorities will have to take into account subsidence when using the flood barriers. The researchers believe that the natural barriers that protect Venice may sink between 150 and 200 millimeters over the next four decades, unless the government reinforces the underlying sediments.
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What are the options if the floodgates are ineffective and subsidence continues? There is but one other solution—abandonment of the city. The huge sums of money required to move or jack up historic buildings and effectively rebuild the city in place on artificial foundations are simply not going to be available—given all the other calls that will arrive for assistance with rising sea levels from other Italian cities and elsewhere in the world. Many Venetians have already relocated to the mainland, but much more is at stake—the future of one of the world’s historical treasures. The cost of moving even a few buildings is likely to be far beyond the capabilities of a sophisticated industrial society, even if the political will to save Venice is in place.

Venice is a sobering wake-up call, a prototype for what may happen to many low-lying cities with much larger populations in the not-too-distant future. Like some Pacific Islands or the Maldives in the Indian Ocean, Venice is a place in danger of vanishing from the face of the earth. There’s a real chance that the historical theme park of today will be the underwater ruin of tomorrow. Even so, the plight of this much-treasured city pales alongside the vulnerabilities of twenty-first-century megacities, where millions will have nowhere to go.

7
“The Abyss of the Depths Was Uncovered”

Shortly after daybreak, and heralded by a thick succession of fiercely shaken thunderbolts, the solidity of the whole earth was made to shake and shudder, and the sea was driven away, its waves were rolled back, and it disappeared, so that the abyss of the depths was uncovered and many-shaped varieties of sea creatures were seen stuck in the slime … Many ships, then, were stranded as if on dry land, and people wandered at will about the paltry remains of the waters to collect fish … Then the roaring sea, as if insulted by its repulse, rises back in turn, and through the teeming shoals dashed itself violently on islands and extensive tracts of the mainland, and flattened innumerable buildings in towns or wherever they were found.
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The Roman historian Ammianus Marcellinus’s dramatic account of the great earthquake that struck Alexandria on July 21, 365 C.E., understates the extent of the catastrophe. Thousands drowned; ships ended up on house roofs, some cast so far inland that they rotted where they lay. The disaster was so traumatic that Alexandrines commemorated the anniversary for two centuries.

Alexander the Great had founded what was then a small town on the western Nile delta coast in 331 B.C.E. Alexandria, named after the great conqueror, soon became one of the busiest ports of classical antiquity. The cosmopolitan city, with its more than three hundred thousand inhabitants, was a hub of commercial activity, a great center of learning
famous throughout the Mediterranean world. Today, almost nothing remains of the harbor of two thousand years ago, which lies below sea level, the victim of natural subsidence.

Until recently, all we knew about the port came from descriptions by Strabo and other classical authors, and maps based on their writings over a century ago. Businessman turned archaeologist Franck Goddio has used electronic surveys of the now-sunken harbor to reconstruct the great harbor, with its breakwaters and famed lighthouse, the Pharos of Alexandria, one of the Seven Wonders of the Ancient World.
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It is said to have been 140 meters high, a square tower with an iron fire basket and a statue of Zeus the Savior. An elaborate complex of palaces, temples, and smaller harbors lay within or close to the port. Subsidence in the order of five to seven meters since antiquity has effectively buried the port. Thousands of exploratory dives have yielded dozens of finds buried in the shallow water, many recovered with their exact positions marked by GPS, others, like the remains of a thirty-meter ship of the first century B.C.E., still left in place. Smaller artifacts include numerous magnificent artworks, well-preserved columns in pink granite from Aswan in distant Upper Egypt, and the remains of a palace said to be associated with Queen Cleopatra.

The Roman coastline has long vanished underwater. Six and a half kilometers offshore lie the remains of Heraklion, another port founded by Alexander, doomed by a combination of subsidence, earth movements, and shoreline collapse. Heraklion, the ancient Egyptian Thonis, lay on a peninsula between several port basins to the east and a lake extending to the west. The city with its bustling port controlled access to the now-vanished Canopic branch of the Nile. According to Herodotus, Heraklion was the mandatory port of entry for all ships arriving from “the Greek Sea.”
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Goddio and his colleagues have located an imposing temple to the sun god Amun, and also more than seven hundred anchors and twenty-seven wrecks dating to between the sixth and second centuries B.C.E. A large channel once passed through the city, linking the port to the lake and the river. The now-vanished port, finally destroyed by an earthquake during the eighth century C.E., was a gateway to Egypt for many centuries before Alexandria rose to prominence.

The fertile soils of the delta with its lagoons, marshes, and wetlands extended inland from Alexandria. They were a granary and the source of ancient Egypt’s wines. Delta vintners nurtured fine wines, which enjoyed a gourmet reputation. The third-century Greek author Athenaeus, from the delta city of Naukratis, loved the wines from Mariut, southwest of Alexandria: “excellent, white, pleasant, fragrant, easily assimilated, thin, not likely to go to the head, and diuretic.”
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RED WINE: the blood of Osiris, the god of resurrection. An early pharaoh, Scorpion I, went to eternity in 3150 B.C.E. at Abydos in Upper Egypt.
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Three rooms of his sepulcher were veritable wine cellars, stacked with over seven hundred wine jars containing nearly forty-five hundred liters of fine vintages imported from the Levantine coast and from vineyards inland. Several centuries later, the pharaohs established their own royal winemaking industry to satisfy their desire for wines, often laced with figs. An Old Kingdom pyramid text tells us that deceased pharaohs dined off figs and wine, which it called the garden of the god. Such meals nourished the pharaoh in eternity.