guia do novo coronavirus
Imprimir Republish

Dieter Muehe

Dieter Muehe: Don’t forget the sea

Geographer says that it is crucial to monitor the coast and the ocean to find out what is actually going to change in terms of the climate

LÉO RAMOSThe answer given by geographer Dieter Carl Ernst Heino Muehe, from Bahia, to the request for an interview from Pesquisa FAPESP almost sounded like a bluff. “Come to my apartment in the city of Niterói, and we can talk. I’m retired and I rarely go to Fundão”, he said, referring to the campus of the Federal University of Rio de Janeiro (UFRJ), where he was a full professor and guidance counselor to doctorate students. At the age of 70, his quiet and apparently shy voice over the telephone conveyed the impression that this was a tired researcher, dedicated solely, at this time of his life, to raising his grandchildren.

The reality of Dieter Muehe is completely different from the impression caused by his discreet attitude. During the interview, this offspring of German parents, who was born in the town of Maragogipe, in the State of Bahia’s Recôncavo Baiano region, placed two books on the table – both are very important books for people who study the Brazilian coast and for mayors of seaside towns. The first book, Erosão e progradação no litoral brasileiro, prepared for the Ministry of the Environment/MMA) was launched in the second half of 2007. The book is a detailed study with indications of where the coastline is receding because of erosion, and where it is expanding, because of progradation, the excessive depositing of sediments. The other book, Rio, próximos 100 anos – O aquecimento global e a cidade, was published last month.  The objective of both books was to provide scientific subsidies for city governments to deal with the possible consequences of global warming in the forthcoming decades.

Both books had the active collaboration of Dieter Muehe, who was the coordinator of the several groups of researchers from a number of different fields. In the interview below, he talks about other projects, some of them outstanding, such as his active participation in Brazil’s claim to rights of over 350 miles (650 kilometers) of ocean stretching from the coastline. He also emphasizes the importance of monitoring the seas methodically, with equipment such as tide and wave gauges, among others. “Only more information will allow us to know, in the upcoming years, what is really going to change in terms of the climate and what the consequences of these climate changes will be on the population,” he warns.

Winner of the Conrado Wessel 2003 award in the Applied Ocean Sciences category, Dieter Muehe has one daughter and two grandsons. He and his wife live near the beach in the city of Niterói. On weekends, the family often travels to the mountain resort of Itatiaia, where they own a cabin, to relax in the mountains, far from the sea. Below are the main parts of the interview.

One of the most controversial points in the discussion and research on global climate changes has revolved around the possible increase of sea levels. As an expert on the coastline, what is your opinion?
This is always a good question, even though there are few reliable answers. We have seen all kinds of studies for and against the predictions of the Intergovernmental Panel on Climate Changes/IPCC, as for example, the effect of ocean currents on delaying global warming, the stability of the permafrost, that is, the underground layer of frozen soil, the recent discovery that methane hydrate is released from the bottom of the ocean in Siberia, an effect which, if it expands, will significantly increase the greenhouse effect. The importance of all these issues is that, for the first time ever, there is worldwide concern about the ocean environment. In relation to the sea, the only concern is that observations have to be made on the basis of continuous monitoring. And this is a big problem in Brazil. There is very little continuous monitoring of the coastline or the sea here in Brazil. In terms of the seacoast, we are beginning to create a network to report the effects of coastal erosion on oceanographic phenomena. The atmosphere will provoke changes, and the response to this will be the temperature of the waves and the rise in the level of the sea. In other words, the sea and how it moves is one of the main control mechanisms of the coastline.

Why is monitoring still such a huge problem in Brazil?
In relation to the monitoring of the coastline’s movements, this kind of work is usually conducted by groups of researchers from universities. Their objective is usually to write a paper or a thesis and then this is interrupted after they conclude their work. Measuring the tides in itself, which is so important nowadays, was conducted with navigation objectives, and not to indicate high and low tide tendencies. The attempt to interpret long-standing graphic illustrations of tidal movements has resulted in worries about the rise in the level of the sea; this concern is something recent. For example, the only long-term tide gauges are found in Cananéia (State of São Paulo) and Ilha Fiscal (State of Rio de Janeiro). Tidal movements were first measured in 1781; however, this was not done continuously. Beginning in 1831, the movements were registered continuously in the port of Rio de Janeiro. These graphs were used as a reference to set the boundaries of the lands owned by the Navy. In fact, the boundaries of these lands are based on the average level of the highest tides measured by the early tide gauges. In general, even though we now have an extensive network of tide gauges along the seacoast, only a few of them actually determine the variation of the level of the sea in the course of time, because of recording failures or changes in their positions. The perception of the need to conduct these measurements is not only to check the tidal movements but also to identify whether the behavior of the tides has changed; to this end, it is necessary to obtain continuous records for a number of decades – 30, 40 or 50 years – to identify a tendency. The reason is because of the short-term variations, some of them corresponding to a few years and even one or two decades, which, if projected for a longer period of time, would incur many serious mistakes.  This is a long-term problem.

Do you mean to say that instability is the normal situation?
Yes, and it can change radically because of climate change. When we look at our coastal plains, we see beach ridges aligned in a parallel position. Satellite photos show this very clearly. All of a sudden, these beach ridges change direction, and each one represents a position along the coastline. What happens? We have records of events that happened thousands or hundreds of years ago, which show changes in the preferred direction of the waves and where the coastline changed direction to adapt to a new situation. This represents accumulation at one point and erosion at the other point, as the morphological response to climate changes. We have to establish points where these movements are registered on an on-going basis. With this in mind, we have just concluded a pioneering project in Latin America, in partnership with the city government of Rio de Janeiro, and research teams with researchers specialized in geomorphology, oceanography, engineering and health care, among other fields. The objective was to obtain a diagnosis of the potential vulnerability of the city. This study was sponsored by the Instituto Municipal de Urbanismo Pereira Passos center for urban studies, and the name of the project is Rio, próximos 100 anos – O aquecimento global e a cidade. A similar study was conducted soon thereafter, encompassing the entire State of Rio de Janeiro, at the request of the Office of the Secretary of the Environment. These studies evaluate the impact of climate change on sea levels. One of the problems we had to deal with was the lack of detailed maps to highlight regions subject to flooding, which is a much more serious hazard than coastal erosion, because it affects many more people.

Why is this study important?
It’s quite unusual for a city government to contact the academic community and request a diagnosis on a problem of vulnerability which will only take place in the rather distant future. Something similar has been done in New York and London, but not in such an encompassing manner. Nowadays, we have a more comprehensive view of the various aspects related to climate changes that might occur and affect Rio de Janeiro. Based on the data we have so far, we can foresee the floods that might occur in 70 years. If the city government authorities fail to do anything about this, then the inhabitants of Rio de Janeiro might even file complaints in court. The city government authorities will have to take on some responsibilities, such as preventing regions at risk from being populated.

Does erosion help cause floods?
Erosion means that the coastline is receding. Normally, the back part of the beach is comprised of a belt of sandy terrain, situated at a higher level. Very often, these regions are populated with sand dunes. In Brazil, the level of the sea rose on two occasions in the past. One event of this kind occurred 120 thousand years ago, when the level of the sea was 6 meters higher than the current level. The other such event occurred some 6 thousand years ago, when the level of the sea reached a maximum of 3 meters in comparison to the current sea level. Each time this happened, the sea built these sandy belts that act like barriers, forming lagoons at the back of the beach. Many of these lagoons were filled with sediments, which then turned into coastal plains, and are being populated by human beings. The problem is that nowadays they are at a topography level that comes very close to the current sea level. Today, when it rains very heavily and the sea level goes up, the rainwater has nowhere to drain and floods occur. The situation becomes much worse when rivers flood and it rains heavily. This is already happening in Rio de Janeiro and in other cities built on the edge of estuaries.

If the level of the sea rises, as foreseen in some scenarios, what is going to happen to the more vulnerable cities?
The situation tends to get worse, not only because of coastal erosion or floods, but also because of extreme meteorological conditions, such as very strong winds that cause cyclones. The ocean is crucial, especially because any major climate change is closely related to the ocean’s circulation, both on the surface and underwater. We have now begun to monitor the sea with buoys. There is an international program called Goos, the acronym for Global Ocean Observing System. Brazil has joined this program and, among other actions, we will launch and monitor the oceanographic buoys. Other projects are being implemented, such as the creation of a network of wave gauges in shallow waters and the expansion of the network to monitor the sea level.

Is the lack of sea monitoring a problem specific to Brazil? Do the British, the Portuguese and the Spaniards, who have a long seafaring tradition, monitor the sea?
Not much attention was paid to the sea because we were naturally focused on mineral resources and farming on the continent. This situation also existed in developed countries. In the 1970’s, I remember hearing complaints in Germany that the country was turning its back to the sea. People were much more concerned about geology then. Of course renowned oceanographic institutes already existed in those times. But the tradition of conducting research on the oceans was interrupted during the Second World War. Nowadays, oceanographic research and all of the related fields, is being extensively developed in those countries, but I am specifically referring to the monitoring of the coastline, that is, the continuous monitoring of oceanographic and meteorological variables able to detect changes in patterns and identify tendencies.

This is a modern-day concern…
It certainly is. Let us take the oil platforms in the North Sea as an example. The energy of a wave is determined by the square of its height. If a one-meter wave has energy 1, a two-meter wave has twice the energy as that of the first wave. But a four-meter wave has 16 times more energy. That is, after a slight threshold, the increase is exponential. Increases of 30 centimeters in the maximum height of the waves means there is a need to design much more robust structures for the platforms. This has been perceived through measurements. Now we’re talking about coastal management in operating terms and plans on what to do in terms of the coastline in the event of climate change. We need information to make decisions. Past information cannot be retrieved because of the lack of data sequencing. We have to do this now, so that we can glimpse a tendency that will materialize in the next 20 or 30 years. A consensus was reached in Rio de Janeiro about the need to create entities that will focus on data gathering.

Who will be responsible for the metering in Rio de Janeiro?
We don’t know yet. We have not advanced on this issue because of time constraints.

Would this monitoring be more efficient if conducted by an institute?
In Rio de Janeiro, we felt that it would be more efficient if an institute were to coordinate this effort, and be responsible for coastal management, which ideally should be extended to the state’s entire coastal region. This is a complicated administrative action. We already have entities that are responsible for a number of tasks. We would have to organize this harmoniously for the action to be successful. It is really a political decision. These are the entities that can generate the information we need.

Could you describe the work with the Ministry of the Environment on the use and development of the coastal regions?
I developed an overall project, which encompassed the demarcation of the seashore as the preliminary approach. This is a very simple idea, which takes into consideration the slope of the bottom of the sea. What happens to the receding coastline when the sea rises a given number of centimeters? The coastline recedes from something like 30 to 40 meters in some places in the Southeast and the South. This tends to increase in the North and Northeast, because the platform at the bottom of the sea is very shallow and the slope is not as sharp. The sea allegedly receded more in that region. These issues were discussed with the coastal management people at the Ministry of the Environment. My work is only one of the points of the Projeto Orla, which focuses more on events that happen on that specific coastal strip. In fact, some limits have already been established: nothing can be built on a strip that starts at a width of 50 to 200 meters from the waterline, or at the end of the sand dunes and at a depth of 10 meters. The project is being implemented in a number of municipal regions in coastal states. All of this takes time, because it is difficult to take action in some places. Most of the local governments do not even have a technical team that can conduct the correct evaluation. The State has to become more actively involved. Let’s go back to the case of Rio de Janeiro: here we have an obstructed coastline. The beaches have walls behind them; it is impossible to make any adjustments. But if the level of the sea rises in an unpopulated region, without walls, the coastline will recede and extend the beach further back. This is not a problem. The awareness of erosion has increased because many regions have become populated.

Which professionals work in this kind of program nowadays?
There are people from the field of marine geology who are part of a Geology and Marine Geophysics Program. These are researchers involved in marine and coastal research; they work at most of the federal universities. These groups have joined this program, which is actually an informal association of researchers who began focusing on the field of marine geology in Brazil. The first outing was held in 1969, when they discovered that the Amazon River has a canyon on the continental slope. Previous projects had stated that Brazil did not have any canyons. This proves that our continental shore was virtually unknown. This group also included oceanographers and geographers right from the start. The oceanographers also began to show interest in the beaches and not only in the oceans. This group began to conduct systematic research studies with the help of the Navy. The Navy, together with Brazil’s National Scientific and Technological Development Council/CNPq, motivated studies in the sense of setting up laboratories along the seacoast and provided ships for this endeavor. A meeting was held every year to define the regions to be surveyed, especially for the purpose of gathering sediments, corroborations, geological surveys, heavy metal analyses, etc. This endeavor became so important that it resulted in the creation of the Remac Project – Reconhecimento da Margem Continental Brasileira (reconnaissance of Brazil’s continental shore). This is when Petrobras, the Department of Mineral Production, the Mineral Resources Research Company and the academic community, through the CNPq, joined in. These people worked full time on the project, together with the oceanographic ships of USP and Woods Hole, to conduct a global survey of the seashore, that is, the platform, the slope and the continental rise, including geophysics, geomorphology, and sedimentology. The result was a new threshold of knowledge about our continental shore.

What is a continental elevation?
First comes the continental platform and then the abyssal plain. The transition between the two is known as the slope. Very often, there is also a transition, called rise, between the slope and the abyssal plain. Based on these geomorphology units, Brazil has battled to extend its jurisdiction over its territorial waters beyond the 200 nautical miles from the baseline, as established by the United Nations Convention on the Law of the Sea.

Are you referring to the 350 miles for the exploration of natural and mineral resources?
Yes; or the limits should extend even farther, depending on the situation.

Has this issue already been resolved?
I am a member of the referred group, and many of our proposals have already been accepted. The proposals were submitted to the limits committee at the UN, and the committee feels that we are asking for too much in certain regions. We believe that we can convince them otherwise.

So 350 miles, give or take a few miles, will definitely remain under Brazil’s jurisdiction?
Relatively so. Brazil controls mineral resources on the bottom of the sea. In the exclusive economic zone, which extends up to 200 nautical miles, Brazil controls fishing and mineral resources on the seabed and under the continental shelf. If Brazil fails to exploit the fishing stock, another country will have the right to do so. The same rule does not hold true for mineral resources. Exploration of mineral resources can go beyond the 200 miles if the continental shelf is wide enough to expand the legal platform beyond this limit. That is why the limit can be extended to a maximum of 350 miles. The importance of extending our maritime frontier becomes evident when we realize that oil drilling ventures are coming close to the 200-mile limit – that is, the limit of our Exclusive Economic Zone.

What else does the United Nations need to accept Brazil’s claim?
The limit is defined from the baseline of the continental slope. The problem is to define where the baseline of the slope is, because this is not clear sometimes. Some geomorphologic features, such as underwater mountain chains, allow countries to extend their maritime jurisdiction. This, however, entails geomorphologic and geological arguments strongly based on geophysical and topographic data. We still need to submit the findings of recent surveys to clarify some controversial points, after which we will definitively establish our maritime limits.

LÉO RAMOSYou are a geographer, but does your work encompass all fields of research?
Yes. Geography includes marine geography. In fact, oceanography stemmed from geography, but grew apart as specialization increased in the different branches of oceanography. The relationship between geography and the sea has always been coastal morphology. Geomorphology itself is practiced within physical geography, geology, and engineering. What is geomorphology? It is the understanding of the processes that shaped landforms, and not only their description. A beach is the tip of a sedimentary prism, the depth of which ranges from 10 to 20 meters, depending on the energy of the waves. Everything that happens in this strip is intimately connected with its morphology. In fact, I suggested that the depth of ten meters be established as the ocean limit of the shore.

Was your suggestion accepted?
Yes. This limit was adopted in the course of discussion groups that took place at the time the Projeto Orla was being defined. We had to establish the oceanic limit and the internal limit. I suggested ten meters because normally this is where waves begin to mobilize sediments and also to prevent dredging operations from being conducted in this region. Dredging alters the morphology of the sea bottom and the balance of the sediments.

A major part of your work includes issues related to coastal populations.
The inclusion of social realities in studies on physical issues is a complicated matter. There is no problem if beach erosion affects unpopulated regions. However, climate change hazards will affect populations. It is crucial to identify where these populations are located, and to what extent they are able to react ? the strength to react weakens with poverty. The poorer the population, the less chance it will be able to defend itself. We are conducting a study on the physical and social-economic vulnerability of the coastal region in the Região dos Lagos in the state of Rio de Janeiro. This study includes physical and social/economic aspects. The social/economic factor is always a complicated one, because the statistics are always presented in the form of spatial low resolution units. The smallest unit is the area that a census taker from the Brazilian Institute of Geography and Statistics/IBGE can cover. These units are not fixed units ? they can change, but this is the closest we can get to at the moment. Right now, one of my doctorate students is working on this.

Last year, you participated in a detailed research study on erosion. Could you elaborate on it?
I coordinated a major project conducted by the group connected with the Marine Geology and Geophysics Program, which resulted in the book Erosão e progradação no litoral brasileiro. The book shows that the coast is not only undergoing erosion processes. Some sectors are showing clear advances. Everything stemmed from the idea of conducting a research study on erosion in our coastal regions, but we did not have the funds to conduct the study. I was able to get the project approved by the executive committee of Goos. They realized that this kind of survey was aligned with the philosophy of the program, because it would provide a basis for monitoring. The proposal was submitted to the Inter-ministry Committee of Ocean Resources, in Brasilia. The Committee granted us R$ 47 thousand; the sum was allocated to different groups, according to each group’s specific needs. In fact, and this has to be publicly stated, the project was the result of years of investments by the CNPq, by state research promotion agencies and even funds provided by the researchers themselves. We were able to have state-of-the-art knowledge on the coastline in our hands. This knowledge will become obsolete very quickly, but it will help us define what actions should be taken today. We need more equipment, ranging from remote sensors to equipment for geophysics and oceanography. For example, to redo a beach, we need the appropriate sand, which is found on the continental shelf. We have to find out what is causing the erosion. We have to become familiar with all the processes, the group of forces that move sediment from one place to another or keep it in the same place.

Does recovering a beach mean taking the sand that went back into the sea and returning it to the beach?
Yes.  But this is very expensive. Cuba has beaches that are recovered every year, but the number of tourists that go to these beaches makes this effort worthwhile.

Do we recover beaches here?
Rio de Janeiro’s Leblon Beach has already been recovered a number of times. Sometimes, the sand remains on one side for a long time and then moves towards the Arpoador, at the other end. The solution is to throw on more sand.  Sometimes – this is not an issue of moving from one side to the other – storms carry the sand to the open sea, far away, and this sand never comes back. The solution is to bring in sand from somewhere else. On Copacabana Beach, the recovery was successful in terms of widening the beach. But the quality of the beach is not the same as it used to be. To begin with, most of the sand on Copacabana Beach came from Botafogo Bay, so it’s not the typical sand found on oceanfront beaches. The surfing zone got smaller, but we don’t see this. The waves now break closer to the beach. But a much bigger problem was solved, which was the lack of space for traffic.

From what you said during your interview, at the age of 70 you are still involved in many activities.
I continue doing what I used to do, which is field research with students. I also provide consulting services. I don’t want to stop.

Republish