Measures to adapt to climate change are announced in Santos, São Paulo

Brazilian and foreign researchers suggest adaptive measures to address the consequences of rising sea levels

By Samuel Antenor in Santos  |  Agência FAPESP – An international study on the rise in sea levels caused by climate change in Santos, a port city on the coast of São Paulo State, Brazil, has resulted in a set of proposals that were presented to the Santos Commercial Association on December 1, 2015.

At the meeting, researchers, as well as representatives of civil society, the Brazilian Navy, and the Brazilian Army discussed proposals for the coming years, designed to tackle the consequences of rising sea levels for Brazil’s largest port, in light of the projected 2°C global temperature rise by the end of the century.

The suggestions presented by the scientists are part of the second stage of Project METROPOLE, “an integrated framework to analyze local decision-making and the adaptive capacity to large-scale environmental change: community case studies in Brazil, the UK and the US”. This project includes research on the rising sea level and coastal flooding in Broward County, Florida (USA) and near the town of Selsey on the Sussex coast of England (UK). 

The study was conducted by Brazilian researchers at the Natural Disaster Surveillance & Early Warning Center (CEMADEN), the National Space Research Institute (INPE), the University of São Paulo (USP), the University of Campinas (UNICAMP), and the São Paulo Geological Institute (IGSP), in partnership with colleagues at the University of South Florida (USA) and King’s College London (UK), as well as technical staff employed by the City of Santos. The project was supported by FAPESP under the aegis of a cooperative agreement with the Belmont Forum.

Santos was chosen not only because of its geographical characteristics and strategic economic importance to Brazil but also because it has the country’s most complete database of tides and sea levels (recorded since 1945 by a network of tide gauges and since 1993 by satellite, read more about Project METROPOLE at agencia.fapesp.br/22129).

“An estimate of the average sea level trend was produced using tide gauge data and dynamic topographical surveys by satellite altimetry, considering the reliability, stability and consistency of the data,” said Luci Hidalgo Nunes, a researcher at UNICAMP and a participant in the project.

The data collected by the researchers was entered into a geoprocessing software platform called COAST (Coastal Adaptation to Sea Level Rise Tool), which was developed by a US-based company and was also responsible for storing the data from the three cities studied in Project METROPOLE.

In the case of Santos, socio-economic variables were correlated with georeferenced spatial data and variables relating to the rise in sea levels.

These datasets were the foundation for two estimations regarding the impact of rising sea levels on the southeastern and northwestern portions of the city. In aggregate, these areas total 13 square kilometers and have a population of 117,000. Sea levels in these two areas are predicted to rise between 18 cm and 23 cm by 2050 and between 36 cm and 45 cm by 2100.

Adaptive measures

Currently available scenarios show that heavy rain and coastal storm surges in the Santos area will be more intense and frequent in the coming decades. This is probably due to global warming and resulting sea level rise, as well as other possible extreme events.

Various measures were evaluated and recommendations were made to strengthen coastal defenses in Santos. In addition to mangrove conservation and rehabilitation, the proposals included new infrastructure such as locks, weirs, and flood barriers for tidal river control; construction of drainage canals; beach nourishment at Ponta da Praia (adding sand and shingle to reduce wave erosive power); and construction of a breakwater off the southeastern shoreline.

In the northwestern part of the municipality, the proposed adaptive measures include channel dredging; creation of a system of barriers, weirs, and pumping stations; and mangrove rehabilitation. Beach nourishment was also recommended in Ponta da Praia in southeastern Santos, as well as construction of a sea wall, installation of pumps, and a system of canal flood barriers.

Two scenarios were used to evaluate the cost of implementing the proposals compared to that of the status quo. The cost of the adaptations and projected losses were estimated solely on the basis of property values in the two areas. Costs relating to other variables, such as health and mobility, were not computed.

For a projected sea level rise of 45 cm by 2100, the economic damage could reach R$236 million in the northeast and exceed R$1.0 billion in the southeast if no adaptive measures were to be taken. With adaptive measures, damage to the northeast would fall to R$64 million and the southeast would suffer no damage.

The criteria used for the estimates were the same used for comparable projects in other countries, and infrastructure construction costs were calculated by city officials.

“Our aim was to give decision-makers the best possible information for future urban planning, make recommendations on action plans, and explain the benefits,” said José Marengo, CEMADEN’s head researcher and principal investigator for the METROPOLE project in Brazil.

Public policy

The project’s goals are to utilize the knowledge resulting from this research to design measures to address problems caused by climate change, support decision-makers, and contribute to the formulation of public policy. To this end, the City of Santos has issued an executive order setting up a municipal committee on adaptation to climate change. The decree was also published on December 1.

The order suggests the creation of an organizational framework involving government, industry, and representatives of civil society to plan and oversee implementation of the recommended measures.

“You can’t just sit back and wait for a disaster to happen before leveraging scientific knowledge about climate change to formulate public policy. You have to act preventively,” said Roberto Greco, a professor at UNICAMP’s Geoscience Institute and a member of the project team.

The participants in the meeting discussed different ways of funding the measures, as well as the possibility of campaigns to educate the public and raise awareness of the need to take action sooner rather than later. Another point of discussion was how to ensure participation of Santos citizens in the process.

The discussions held during the meeting highlighted the importance of making the process as civic and participatory as possible. All social groups, as well as individuals, should have membership in the committee proposed by the municipal government.

“Santos is way ahead of everywhere else in Brazil in terms of this level of information,” Nunes said. “The project has been possible only with the city government’s assistance, providing information and technical support on its utilization. It would have been impossible to implement a project like this without such support.”

According to the researchers, this is the first climate change study performed in Brazil to consider sea levels along with wind and other meteorological factors, with a goal of informing public policy and decision-making.

The next stage of the research will consist of comparing conditions in Santos, Broward, and Selsey, exchanging information, and making an efforts to raise awareness of the need for urgent adaptive measures.