Around 10 per cent of the world's population live in coastal zones at risk from rising sea levels. So what can be done?by Bill McGuire / November 19, 2019 / Leave a comment
When it comes to the threat facing coastal cities from rising seas, Venice has a clear head start. Even at the best of times, it is, after all, half-submerged.
Straddling more than one hundred low-lying islands clustered in a coastal lagoon, Venice has long been at risk due to storm surges and—as earlier this week—from unusually high tides, but increasingly dire predictions of rapid sea-level rise as the century progresses are beginning to sound the death knell for this iconic city.
This week, floods inundated almost ninety per cent of the city, shining a light on just how precarious its situation is. The greatest of the flood tides was the second-highest on record, and within touching distance of the highest ever level, reached in 1966. One thing is certain: it won’t be long before this record goes too.
With global sea level now rising at around half a centimetre a year (and climbing) Venice’s long-term future looks bleak. And there’s more. The whole place is subsiding; the thousands of wooden piles that support it are slowly crumbling and sinking into the mud and marsh beneath. The damage caused by this most recent assault from by the sea is forecast to cost well into the hundreds of millions of Euros, perhaps even topping the billion mark.
But this is likely to be just the start. Future floods have the potential to be far more destructive.
It’s not as if the threat to Venice has only made itself known in recent years. It has long been apparent that, if the city was to have any future at all, then something needed to be done to shelter it from the sea. In 2003, after much prevarication, then Prime Minister Silvio Berlusconi launched a scheme designed to protect the city from the highest flood tides. Sixteen years, and at least seven billion Euros, later, the scheme is still not up and running.
At the heart of the so-called MOSE Project is the installation of floating pontoon flood ‘gates’, tasked with closing off the three entrances that connect the Venice lagoon to the open Adriatic when high seas threaten. Beset by delay, a ten-fold cost hike and the inevitable corruption scandal, the scheme is now planned to become operational in 2022. If and when the pontoons work as planned, they should protect the city from tides as high as three metres. But, it has to be said, Venetians aren’t holding their collective breath.
In any case, even should the barrier function well in coming decades, as the century wears on, a conspiracy of continued subsidence, more powerful storm surges, higher wave heights and the relentless rise of sea level driven by accelerated melting of the polar ice caps will mean it becomes less and less effective.
With several metres of sea-level rise already locked-in, however rapidly we reduce carbon emissions, the bottom line is that Venice is set to lose its battle with the sea, alongside every other coastal city. In a very real sense, the Venice floods act as a bellwether that sounds the ultimate fate of all those communities that cling to the edge of the land.
The quarter of a million Venetians share the low-lying coastal zone with another 680 million or so people whose lives and livelihoods continue to thrive only by the goodwill of the sea. In its 2019 report—The Ocean and Cryosphere in a Changing Climate —the Intergovernmental Panel on Climate Change forecasts that this figure will exceed one billion by the middle of the century.
In common with the inhabitants of Venice, all these people—maybe one-tenth of the human population—will inhabit cities and towns that are increasingly at the mercy not only of steadily encroaching seas but also of more powerful storms, higher tides and bigger waves. With some forecasts for sea-level rise by the end of the century approaching three metres, it is hard to view their future prospects as anything other than grim.