Venice will survive climate change. But less famous cities won’t be so lucky

St Mark’s Square has seen dryer days. Image: Getty.

Venice has flooded. But while worry about the worst floods in a decade and warnings about the impacts of climate change and sea level rise dominate most of the media coverage, there’s a more complex story to be told.

In Venice, floods are a feature, not a bug. The city was founded by people fleeing the Huns. They were safe in the lagoon (a word borrowed from Venetian), where horses and armoured men could not advance: the soggy ground would slow the enemy, the tide would wash them out.

Halfway between land and sea, trade is the only way to make a living. And so Venetians became successful merchants and built a magnificent city, with dazzling palaces and splendid churches filled with delightful works of art.

That city would flood every so often, when the tide was high and the wind pushed the waters of the Adriatic up north. But Venetian buildings are designed to withstand this, and city life bustles around the water.

The cost of protection

Venice has changed – it is primarily a tourist attraction now. Many locals have moved out, their houses converted to hotels, restaurants and holiday homes. The floods have changed, too. The rising sea pushes the flood waters ever higher, and this will get worse in the future. Stronger winds would exacerbate the problem.

The impact of climate change and sea level rise is moderated by adaptation. The Sumerians, the earliest known civilisation in Mesopotamia, knew how to build a dyke: 5,000 years have passed since, and we have learned a lot about how to protect our coasts.

Some places are easy to protect. The Piazza del Duomo in Pisa is vulnerable to erosion, but there is plenty of foreshore to build a dyke without spoiling the view of the Leaning Tower. London will need a new barrier eventually, and the only thing standing in its way is the government’s ability to decide and deliver large infrastructure projects.

Other places are much harder to protect. You can build a seawall in Miami but the water would seep right under it. A seawall would be effective in Dubrovnik but would spoil the Old City. A glass wall would be more appropriate, and expensive. Costs are a concern too in Leptis Magna – an ancient Roman city in Libya – as are kidnappings of skilled engineers.

Off the tourist trail

Research shows that cultural heritage is particularly vulnerable to sea level rise. Of 49 cultural world heritage sites located in low-lying coastal areas of the Mediterranean, 37 are at risk from a 100-year flood and 42 from coastal erosion. Up to the year 2100, flood risk may increase by 50 per cent and erosion risk by 13 per cent across the region, with considerably higher increases at individual world heritage sites.

Although Venice faces a serious threat from flooding, tourism generates so much money that the city can afford to protect itself. As a matter of fact, after the record floods of 1966, the authorities decided to protect Venice. It took a while to agree on the design and the financing. Construction began in 2003 on a set of movable barriers that lie flat on the sea floor for most of the time, but close the inlets of the lagoon during high tides.

This set-up maintains the ecology and hydrology of the lagoon roughly as it is today, which is important as it is the largest tidal marsh in the Mediterranean. The first tests of the barriers have already been conducted. Full scale testing should commence in January 2019, and the project is due to be completed in 2022.

Reports of the death of Venice are premature: €6bn was spent to make sure it will not drown below the rising sea. Why? Because it’s worth it. The media focus on the impacts of sea level rise on places such as Venice feeds the needs of sensationalists. Many people have been there, or would like to go. Around 30m people visited Venice last year. The alarm is raised by the threat of seeing an iconic city destroyed by climate change. Except that in this case, the threat is baseless.


That is not to say that sea level rise is no concern. Cities such as Abidjan in Côte d'Ivoire, Accra in Ghana, Chittagong in Bangladesh, Jakarta in Indonesia, Lagos in Nigeria and Mumbai in India will face greater challenges, when it comes to shielding themselves from the rising sea. Poor and disorganised, the authorities have a hard time providing basic public services – they can ill afford a multi-billion dollar project to protect the coast.

The most worrying impacts of climate change will fall on those unable to adapt, and places off the beaten track face far greater obstacles than those on the tourist trail. Al Gore described climate change as a moral problem. Perhaps we should focus less on the cities and sights we know, which are ultimately safer from climate change, and more on the real destruction that climate change will cause.

The Conversation

Richard Tol, Professor of Economics, University of Sussex.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 
 
 
 

To beat rising temperatures, Vienna launches a network of 'Cool Streets'

A Vienna resident cools off at one of the city's new Cool Streets installations. (Courtesy Christian Fürthner/Mobilitätsagentur Wien)

Over the past several months, Austria has recorded its highest unemployment rate since World War II, thanks to the economic aftermath of the Covid-19 pandemic. With no job or a suddenly smaller income – not to mention the continued threat of the virus – many Viennese will opt for a staycation this summer.  

At the same time, last year, Austria’s capital experienced 39 days with temperatures of over 30°C (86°F), one of its hottest summers in history according to the Central Institute for Meteorology and Geodynamics.

Climate experts expect a similarly sizzling 2020 season, and city officials are now doubling down on efforts to combat the heat by launching a “Cool Streets” initiative as well as a new, state-of-the-art cooling park.

“As the city councilwoman in charge of climate, it is my job to ensure local cooling,” Vienna’s deputy mayor Birgit Hebein proclaimed at the opening of one of 22 new “Cool Streets” on 22 June.

“In Austria, there are already more heat deaths than traffic fatalities,” she added.

Hebein was referring to the 766 people the Austrian Agency for Health and Food Security included in its 2018 heat-associated mortality statistics. The number was up by 31% compared to 2017, and in contrast to the 409 people who died in traffic collisions the same year.

The project includes 18 temporary Cool Streets located across the city, plus four roads that will be redesigned permanently and designated as “Cool Streets Plus”.

“The Plus version includes the planting of trees. Brighter surfaces, which reflect less heat, replace asphalt in addition to the installation of shadow or water elements,” said Kathrin Ivancsits, spokeswoman for the city-owned bureau Mobilitätsagentur, which is coordinating the project.


Vienna's seasonal Cool Streets provide shady places to rest and are closed to cars. (Petra Loho for CityMetric)

In addition to mobile shade dispensers and seating possibilities amid more greenery provided by potted plants, each street features a steel column offering drinking water and spray cooling. The temporary Cool Streets will also remain car-free until 20 September.

A sensor in the granite base releases drinking water and pushes it through 34 nozzles whenever the outside temperature reaches 25°C (77°F) . As soon as the ambient temperature drops to 23°C (73°F), the sensor, which operates from 10 a.m. to 8 p.m., turns off the water supply.

The sensors were included in part to allay concerns about legionella, a pathogenic bacteria that can reproduce in water.  

“When the spray stops, the system drains, and therefore no microbial contamination can develop,” said Dr. Hans-Peter Hutter, deputy head of the Department of Environmental Health at the Center for Public Health at Medical University Vienna, in a televised interview.

Hutter also assured the public that there is no increased risk of a Covid-19 infection from the spray as long as people adhere to the one-meter social distance requirement.


But Samer Bagaeen of the University of Kent's School of Architecture and Planning notes that air cooling systems, like the ones used in Germany at abattoirs, have been found recently to be a risk factor for Covid-19 outbreaks.

“The same could be said for spay devices,” he warned.

Vienna’s district councils selected the 22 Cool Street locations with the help of the city’s Urban Heat Vulnerability Index. The map shows where most people suffer from heat by evaluating temperature data, green and water-related infrastructure, and demographic data.

“Urban heat islands can occur when cities replace the natural land cover with dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat,” as the US Environmental Protection Agency states.


A rendering of Vienna's planned park featuring a Coolspot, which is scheduled to open in August. Click to expand.
(Courtesy Carla Lo Landscape Architecture)

Vienna’s sixth district, Mariahilf, is such an area. The construction of the capital’s first “Cooling Park”, a €1 million project covering the 10,600 square-metre Esterházypark, is designed to provide relief. 

Green4Cities, a centre of excellence for green infrastructure in urban areas, designed the park’s main attraction, the “Coolspot”. The nearly 3.40-metre high steel trellis holds three rings equipped with spray nozzles. Textile shading slats, tensioned with steel cables, cover them.

The effects of evaporation and evapotranspiration create a cooler microclimate around the 30 square-metre seating area, alongside other spray spots selectively scattered across the park.

The high-pressure spray also deposits tiny droplets on plant and tree leaves, which stimulates them to sweat even more. All together, these collective measures help to cool their surroundings by up to six degrees.

The landscape architect Carla Lo and her team planned what she calls the “low-tech” park components. “Plants are an essential design element of the Cooling Park,” Lo says. “By unsealing the [soil], we can add new grass, herbaceous beds, and more climate-resistant trees to the existing cultivation”.

Light-coloured, natural stone punctuated by grass seams replaces the old concrete surfaces, and wooden benches meander throughout the park.

Living near the park and yearning for an urban escape close by, Lo says she’s motivated to ensure the park is completed by mid-August.

“If we don't do anything, Vienna will be another eight degrees Celsius hotter in 2050 than it already is,” Hebein said.

Vienna recently came in first in the World's 10 Greenest Cities Index by the consulting agency Resonance.

“There is no one size fits all on how cities respond to urban heat,” says the University of Kent’s Bagaeen, who points out that Vienna was one of the first European cities to set up an Urban Heat Islands Strategic Plan in 2015.

In the short term, prognoses on the city’s future development may be more difficult: Vienna votes this autumn.

Petra Loho is a journalist and photographer based in Austria.