Will the sea swallow Salvador? City Hall seeks partnership with NASA over this

August and September are not the best months to challenge the sea in Bahia. Last Tuesday, videos went viral showing the invasion of the tide in Salvador, as in the Yacht Clube da Bahia, which had its leisure area invaded by the waves. Impressed, but it is far from an isolated case. It is even quite common at this time of year, as the combination of the cold front, winds, tide and moon table causes these phenomena seen in the Ladeira da Barra club. So, no need to worry? It’s not quite like that either. Despite being natural, it is increasingly commonplace and dangerous. In addition, the City of Salvador is assembling a team to face rising sea levels and is seeking a partnership with the United States Space Agency. That’s right, NASA.

On Thursday, the Municipal Secretariat for Sustainability and Resilience (Secis) held the inaugural meeting of the first working group to tackle rising sea levels, which brings together specialists who seek to reduce the effects of the tidal invasion in the capital. The idea is to err on the side of prevention, seeking palliative measures to face the phenomenon that was common, but is more frequent because of climate change. The group will be formed by specialists from different areas and institutions, such as Inema, Ufba, C40 Network – which brings together several cities around the world that fight against climate change. Besides NASA, of course.

We are seeking technical cooperation from NASA. Iclei is making this link so that we can have a more accurate view of the location. It will be a very important technical support. This cooperation already exists between NASA and Rio de Janeiro and now we want to bring them to Salvador”, explains secretary Marcelle Moraes, head of Secis, the body that is in charge of the project. Iclei is a non-profit organization that brings together more than 2,500 local and regional governments, committed to sustainable urban development. The idea is to have a response from NASA at the next meeting, which still has no date set.
NASA does similar work in Rio de Janeiro. The agency monitors the city’s climate, anticipating extreme weather events and, with that, giving the possibility of a more effective response power. It was also defined at the meeting who would participate in the group, the guidelines and risk zones that need more attention.

Simulation of what Salvador could look like in the year 2100

The working group, after consulting studies, divided the most impacted areas of Salvador into four territories: Ilha dos Frades and Ilha de Maré in their entirety; the region of Paripe, in Subúrbio Ferroviário; a strip that extends from the Itapagipe Peninsula to Comércio; in addition to a sequence of discontinuous spots along the Atlantic coast, which go from Porto da Barra to the northeast border of the municipality, near Stella Maris. Stop and think: Salvador is at risk on all sides. Despite the warning, it’s not time to panic. It is still possible to have tidal invasions until the end of September, like every year. But more often. We looked for the Yacht Clube da Bahia to comment on the frequency of the phenomena at the place, but there was no return until the closing of the edition. However, experts urge caution about the invasion of the sea.

“What happened on the Yacht is nothing out of the ordinary. It happens practically every year, until September. But, because of these predictions of climate change and sea level rise by the end of the century, this phenomenon will become more and more frequent. The tendency is to worsen precisely due to climate change. What happened once or twice a year will end up happening more often”, warns professor at the Federal University of Bahia (UFBA), José Maria Landim, PhD in Marine Geology. In other words: every year, what only happened in one part of the city, may occur in other coastal areas, more frequently.

High tide
For the most serious cases to occur that leave some traces of destruction, such as coastal erosion, shipwrecks and unusual situations like the one at the Yacht Club, a perfect convergence of nature is needed, exactly what happened this week. Salvador was in the so-called high tide of Sizygia, when the tide table is directly influenced by the full moon, raising the water level. This was coupled with the arrival of a storm that further increased the size of the waves and the sea.

“Cold fronts, storms and hurricanes have the potential to increase the size of waves, but this effect changes depending on when the tide is. If a storm hits the coast at a time when the tide is low, the sea level will be low enough to offset the effect of the surge caused by the storm. On the other hand, if the tide is high, it will converge with the rise of the waves caused by the storms and generate ‘giant’ waves”, details the oceanographer and Master in Ecology from UFBA Alice Reis.

For Alice, in fact, the case witnessed on the Yacht is not something abnormal, but it is still a warning. “I don’t see this invasion [do mar] as something anomalous yet. However, Salvador is very vulnerable to any rise in sea level, for sure. It is bathed by the Atlantic Ocean and the Bay of All Saints, has a fully occupied shore, channeled rivers (which are natural water paths), in addition to the history of a large volume of rain falling in a short period of time. We, from science, sometimes feel like the reporters of the end of the world, but it does worry us”.

Imagine this whole scenario with rising sea levels, which is a reality. According to the marine monitoring service of the Copernicus Program (the European Earth observation programme), the sea grows by an average of 3.1 millimeters every year. If this accelerated pace continues, the estimate is that the sea level in Salvador will rise by 50 cm by 2100 if the temperature on the planet increases by 1.5º C in the coming years. Did you think little? This elevation would be enough to leave some tourist spots in the capital underwater, such as Porto da Barra, Gamboa de Baixo and Ribeira. Ilha dos Frades would disappear from the map.

This projection was part of an exhibition in June, at the Salvador 2100 event, based on data from the Climate Central agency, in partnership with the City Council, Konrad Adenauer Foundation, the United Nations Development Program (UNDP), among other institutions. At the exhibition, the public saw pictures of what the city will look like with a high tide level. In the images, it was possible to see beaches like Porto covered by water. It’s no nonsense. In 2021, in this same current period, the sea took over the entire sand strip of Praia do Buracão, in Rio Vermelho.

“It is a climate mutation and events as we saw at the Yacht Club are a wake-up call, a signal that we are receiving [da natureza] of what’s coming around. The tendency is for these hangovers and weather events to become more critical, more acute, and worse over time. Climate change is enhancing these phenomena. It is necessary to adapt the city to this change that is taking place. The city hall is taking a series of important measures in this regard”, says councilor André Fraga (PV), environmental engineer and president of the Special Committee on Climate Emergency and Innovation of the Chamber of Salvador. He was one of the organizers of Salvador 2100.

In 2008, the geologist and researcher at Ufba Abilio Bittencourt published a scientific article about the invasion of the sea in Salvador and its consequences, such as coastal erosion. He made an overview of phenomena that occurred between 1990 and 2006. Interestingly, at that time hangovers also occurred more frequently in the period between August and September.
However, some details stand out. Until September 2006, the phenomena had waves that did not exceed 2.5 meters in height. In last Tuesday’s event, the Navy recorded waves that reached 3.5 meters. In August alone, the Salvador/Mar Grande crossing had its service suspended for a total of 9 days, all because of bad weather and above average high tide.

Salvador also has another peculiarity. All the land located from the Mercado Modelo to the vicinity of Feira de São Joaquim, in the Lower City, was sea that ended up being grounded with the growth of the city. “That region didn’t have much space to occupy. Throughout the 17th century, it is possible to see an advance of landfills over the sea, which was expanded in the following centuries. In the 19th century, the landfill was in what is now the back of the Bahia Commercial Association, in Comércio. Imagine how much progress it made in the following years”, recalls historian Pablo Magalhães, a professor at the Federal University of Western Bahia (Ufob).

To give you an idea, before the start of grounding, the sea was hitting the wall that today has the Elevador Lacerda. Experts do not point to the landfill as a consequence, as there are no studies on the relationship. However, it is possible to stop these waves with some daily attitudes. “We need to reduce the consumption of everything that has greenhouse gases as a source of energy, such as global meat consumption, reduce deforestation and promote reforestation, among other measures. One thing that is rarely discussed is the need to maintain coastal vegetation such as sandbanks and mangroves, including in cities. These vegetations attenuate the force of the waves and protect the coast”, adds oceanographer Alice Reis.

The article is in Portuguese

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