Facing the Stress of the Water Cycle. Interview with Julia Carabias

UNAM Internacional: IIn your acceptance speech at the National College, you spoke of nine natural processes that determine the possibility of a sustainable environment in the future. One of them is the stress of the water cycle. We would like to start the interview by asking you to explain this idea: what are its elements and characteristics?
Julia Carabias: There is a conceptual framework that has been globally adopted for almost two decades: the planetary boundaries framework proposed by the Stockholm Resilience Centre [see UNAM International 11, pp. 152-154, and UNAM International 3, p. 202]. This framework evaluates the state of nine planetary systems that govern life on Earth and defines the limits within which each of these systems operates with stability. To understand their behavior, certain variables are measured and monitored over time. When those limits are exceeded, the safe space for humanity and other living beings is at risk. Of the nine limits, we have already exceeded seven, including the freshwater cycle. That is why we say we are in a water crisis, which implies water stress.

Water is distributed very unevenly across the planet: it is abundant in the tropics and scarce in deserts. Ecosystems are adapted to these conditions, but humans are not. We all know that water, in addition to being a vital element, does not disappear; it is transformed between its different states, and its quality changes. This is why the availability and accessibility of water for societies and wildlife changes and decreases when it is misused. Why? Because we are intervening in the cycle without caring for its functioning.

Julia Carabias with a working group in the Lacandon Rainforest.

  Julia Carabias

The natural water cycle that occurs in a waterhed is determined by a series of physical, geographic, atmospheric, biological, and geological factors. When we modify them, its functioning changes. How do we alter them? The first indicator I highlight is the removal of vegetation cover, which determines that the cycle works correctly. The vegetation layer helps evapotranspiration to occur. Although rainfall in a given place depends not only on evapotranspiration because it is also brought by winds, vegetation contributes very significantly—more so in tropical rainforests than in arid zones. When we eliminate vegetation, we reduce that contribution.

A second altering factor is that, by deforesting ecosystems, the water that precipitates falls directly to the ground, which is then carried away by runoff, causing erosion. Sediments accumulate in water bodies and cause silting.

We also alter the hydrological cycle by paving. We seal the soils when building urban areas and infrastructure, which aggravates the process of non-infiltration.

Another alteration is pollution generated by human activities in a waterhed: most of the water that is used is discharged with pollutants. Very few countries treat all their water before discharging it. This pollutes lakes, streams, and rivers until they reach the sea, and also affects aquifers through the infiltration of contaminants.

We should also add that most of the world’s large rivers have dams, impacting water flows and the mobility of aquatic species.

All these alterations modify the quantity and quality of available water, which is severely aggravated by climate change. Climate change causes the amount of frozen water to decrease, glaciers to be lost, droughts to lengthen, floods to increase, and rains to concentrate in fewer months. All of this has significant impacts on food production, human health, and on the behavior of species’ biological cycles.

The hydrological cycle is also altered by the disorderly occupation of waterheds and inappropriate land use. Population continues to grow and increases the demand for natural resources, including water. This situation can turn a basin with sufficient water into one with water stress. A clear example is the Basin of the Valley of Mexico, among many others.

Field work session.

  Julia Carabias

UI: Article 4 of the Constitution enshrines the human right to water. What is our situation in relation to this right in Mexico?
JC: Water in Mexico is a national asset. The 2012 reform of Article 4 established the right of every person to access sufficient water, its disposition, and sanitation for personal and domestic consumption. The coverage of these services has improved; however, for nearly ten percent of the population it is still not guaranteed, and if we consider population that does not have continuous access to potable water, it may reach almost half the population. In addition, differences are very marked between urban and rural populations; between states of the Republic—with Chiapas, Guerrero, and Oaxaca having the greatest deficiencies—and between sectors of the population. Indigenous populations and those living in poverty suffer the most from these deficiencies. Guaranteeing the human right to water implies universal and quality coverage, which requires differentiated policies for each situation and region. The challenge is enormous and implies increased investment and a high level of coordination between different government levels, since jurisdiction is distributed among the Federation, states, and municipalities.

THE AMOUNT OF WATER IN MEXICO IS SUFFICIENT FOR ALL PEOPLE, BUT ITS DISTRIBUTION AND ANAGEMENT MUST CHANGE

In December 2025, the Ley General de Aguas (General Water Law, see pp. 146 in this issue) was enacted, which is the regulatory law for the human right to water and sanitation and prioritizes access to water for personal and domestic consumption. It also links with the right to a healthy environment. The Ley de Aguas Nacionales (National Water Law) was also reformed. Its main changes consisted in, first, eliminating the buying, selling, and private transfer of water rights, and second, to recognize community-based forms of water management. These new laws emphasize integrated water management and adaptation to climate change. The corresponding regulations, which are very outdated, now need to be updated. This closes—at least the Government intends to close—a process of debates around the National Water Law that began more than 15 years ago.

In short, I would say that the amount of water in Mexico is sufficient for all people, but its distribution and management must change, and we hope that the new legislation promotes and accelerates these changes to comply with the human right. This obliges us to prioritize the water that nature requires to maintain the hydrological cycle and human consumption. If we do not consider the needs of the natural hydrological process to keep it functional, we will be destroying the water factory.

That is why it is not feasible to install large projects that are highly dependent on water in regions where it is scarce. For example, in the north of the country, much of the available water is non-renewable water, what we call fossil water—that is, water that was generated in times when the climate regime in those places was completely different from today. Infrastructure and intense water-demanding developments should not be installed in those places. Regional and long-term planning is essential and must take into account the natural resources conditions of each site. But we are not planning with an integrated, long-term vision.

IF WE DO NOT CONSIDER THE NEEDS OF THE NATURAL HYDROLOGICAL PROCESS TO KEEP IT FUNCTIONAL, WE WILL BE DESTROYING THE WATER FACTORY

Team working in the Lacandon Jungle.

  Julia Carabias

UI: This also means there is a geopolitical dimension of water, in that we share water bodies and basins with other countries. We think of the northern border: the Colorado River and the Río Bravo (Grande in the United States). We share basins with the United States and receive water that is not, let’s say, whole, or clean, or not in the quantity that should reach us. How is interest settled in a basin when negotiating with another country, as in the case of Mexico and the United States, or that of the Soconusco on the Suchiate or Usumacinta Rivers, which are border rivers?
JC: We have a binational instrument for water management between neighboring countries: the International Boundary and Water Commission (IBWC), known as “the CILA” in Spanish. But they function very differently in the north and the south. With the United States, the CILA is very active and constantly negotiates delivery and receipt volumes; in the case of Río Bravo, Mexico must deliver water to the United States, and in the case of the Colorado River, the United States delivers it to Mexico. But there are always compliance problems and therefore many tensions. For example, the Colorado River has many dams, and the United States delivers less water than the ecosystems of the northern Gulf of California need. As a result, the wetlands and wildlife of this marvelous, unique natural aquarium are severely affected, especially in the Colorado River Delta. This situation is aggravated by climate change and population growth, because drought in northern Mexico and southern United States is increasingly intense and prolonged, while demand also increases: two problems that interact, and water stress increases. When the discharge volume increases, wetlands recover quickly. Nature’s resilience is wonderful.

The CILA on the Mexico-Guatemala border is not so active. In fact, these topics are avoided in binational meetings. However, there are also problems, but in this case, they are due to water quality and the management of dams on the Guatemalan side. We share the Suchiate River with Guatemala in the Soconusco region. This river’s water are highly polluted by untreated wastewater from riverside populations on both countries. We also share the Usumacinta River basin. The rivers that feed the Usumacinta’s tributaries on the Guatemalan side are dammed. When hurricanes, frequent in the area, fill the Guatemalan dams, they are discharged and flood the Mexican middle and lower basin. In 2020, for example, a dam on the Chajul River, a tributary of the Lacantún River, which in turn flows into the Usumacinta, was discharged. The population on the Mexican side was not warned, and the water from this dam, which came down with great force, carrying many sediments and pollutants, caused severe damage. They changed the course of the Lacantún River, swept away livestock and infrastructure, flooded towns, and deposited contaminated sediments on farmland. No authority wanted to take responsibility, and the people were left to fend for themselves, facing the damage alone. The CILA did not work.

POLLUTANTS FLOW WITH OCEAN CURRENTS AND AFFECT VAST AREAS OF THE PLANET. THE WATER CRISIS IS A GLOBAL CRISIS

The environmental issue is barely incorporated into CILA negotiations, even though it affects strategic ecosystems due to their biodiversity and ecosystem services. How is this possible? We share ecosystems, flora and fauna, biological corridors, and protected areas, but the environment is never a priority to prevent damage and degradation that, sooner or later, affects people.

UI: National policy should be articulated with decisions made in other countries, given that the situation transcends borders.
JC: Yes. Although water is perceived as a local issue, of each country, it is actually a matter that concerns everyone and must be addressed globally and integrally with other natural and socio-economic systems. This has to do with consumerism patterns of social groups, with the production methods of different sectors, with climate change, and land-use change. All these elements are interconnected and have global links and repercussions. For example, water contaminated in one country by excessive use of agrochemicals flows through rivers to the sea and affects the flora and fauna of marine ecosystems, even creating dead zones. Furthermore, pollutants flow with ocean currents and affect vast areas of the planet. The water crisis is a global crisis.

 Monserrat García Silva

UI: How can universities, particularly UNAM, contribute to influencing public policies? What’s your opinion in UNAM’s projects? How could they work not only in terms of research, but also in terms of generating effective actions?
JC: There’s no doubt UNAM plays a major role and has a huge responsibility in the search for solutions to national problems. Knowledge generated at UNAM must become the basis for many public policy decisions. When scientists participate and decisions are made with the best available science, solutions are better and more durable. Otherwise, decisions are fundamentally political. Unfortunately, there are no formal, institutional mechanisms for the knowledge-decision flow. The efforts made are usually based more on personal relationships than institutional ones, and it is common for there to be no continuity after government changes.

A paradigmatic case is that of the National Commission for the Knowledge and Use of Biodiversity (CONABIO), which convenes and gathers knowledge from university researchers and experts and uses it to design public policies and propose solutions to multiple problems related to Mexican biodiversity. Obstacles become apparent later, in policy implementation. But the institution itself is a success story that should be replicated in all areas; CONABIO is an interface between knowledge generation and decision-making.

This is how the Mexican Technological Institute of Water (IMTA) should function, gathering the scientific research being generated in the country to guide water policy decisions. Unfortunately, IMTA has not been able to convene scientists to the extent that CONABIO has. There are agreements and work among researchers, but they are isolated and not articulated around decision-making. UNAM has excellent academics and researchers with international recognition, but they are generally not listened to. We also find the reverse situation: researchers that are unwilling to dedicate time to being heard, even though they should. For example, anyone who does not have time to defend the ecosystems they study or to propose solutions to their multiple problems will soon find that their object of study may have disappeared.

UNAM has huge potential here. Rector Lomelí’s administration is pushing many projects with these characteristics; however, university inertia is very strong, and the speed of problems outstrips the speed of responses. It is necessary to dedicate greater efforts to articulating disciplines to address complex problems and influence public policies. Where is the university agenda that proposes how sustainable water management should be? UNAM must be critical and analytical; not just reactive, but highly proactive.

IT IS NECESSARY TO DEDICATE GREATER EFFORTS TO ARTICULATING DISCIPLINES TO ADDRESS COMPLEX PROBLEMS AND INFLUENCE PUBLIC POLICIES

UI: You have said—we quote verbatim—“Decision-making with the best possible science is obligatory; not doing so must be a serious fault and is not moral.”
JC: Yes. I think that public officers, when they have to make decisions, must be advised by the best available scientific evidence. If, despite science warning of the risks of implementing a project, the project is authorized and environmental damage is caused, the person should be sanctioned and assume responsibility.

UI: Regarding the technologies that are said to transform water management, how are they working? Rainwater harvesting plans, flexible cisterns, green infrastructure—Are they having an impact?
JC: These technologies, despite having proven their efficiency in multiple circumstances, are not incorporated into public policies. Therefore, their impact is rather local; they are successful examples of nature-based technologies, specific to different regions, but isolated in communities, with advice from civil society organizations that implement them or committed university researchers, but they remain at the pilot experience level.

Their management and implementation are not easy, especially due to the dispersion of communities where they should be applied. But that is what society is for. How many hands can multiply efforts if organized civil society is involved? However, social organizations are very weakened. Strengthening them is a priority to recover their multiplying force.

UI: Datacenters that use large amounts of water and are starting to be installed everywhere—Will they put more pressure on these circumstances?
JC: A serious problem. Storing and processing large volumes of data consumes alarming amounts of energy to operate the data centers and of water to cool them. Users are not aware of this. We must be much more rational in our use of this tools, using light models when possible, making fewer but more efficient queries, minimizing unnecessary data storage, and reusing the heat generated by data centers, among other measures. If UNAM advances in this direction, it must take environmental impacts very seriously and mitigate their effects.

UI: From your experience as a scientist and environmental activist, what message would you give to younger university generations regarding their responsibility to protect water management?
JC: I am convinced that there are solutions to the crises. If that were not the case, I would have abandoned these battles long ago. The role of universities is to train high-level professionals with a critical conscience. No matter what discipline they are trained in: to build a better future for all, it is essential that in their professional lives they have a conscience of respect for nature and a vision of the problems life faces—not only human life, but all living beings.

Thus, university students’ main commitment is to train well. The university offers multiple opportunities to receive quality information and to develop a multidisciplinary analytical vision. It also facilitates conditions to learn to collaborate and organize at many scales. After the long period of isolation during the COVID-19 pandemic, many activities and habits of collective life have been lost. Few people attend many conferences, debates, meetings, as well as other social activities like cinema and theater. We need to nourish that university life. There is nothing more wonderful as a student than to fully experience the campus and, between classes, films, conferences, exhibitions, and other cultural activities, to become better people. Those young people with a different attitude and conscience will make the change of course toward a better life, the one they choose. We cannot continue doing more of the same, staying in our comfort zone, ignoring our neighbors and the health of the planet. I believe we need all university community to better orient our work.

UI: Regarding your work in the Lacandon Rainforest, which is an important region for biodiversity, what actions do you consider urgent to protect this space and what is its role in water regulation?
JC: The Lacandon Rainforest, where I work, is the most important freshwater capture area in the country. The Usumacinta and Grijalva basins provide 30 percent of Mexico’s freshwater. The Usumacinta is a living river; water runs freely—one of the few large rivers with this condition. That is why we have always opposed attempts to build a dam, which has been a very tempting dish for engineers, and fortunately we have managed to stop it, administration after administration. The basin, on its Mexican side, already has very positive instruments for conserving the hydrological cycle and biodiversity. Among them are natural protected areas that conserve ecosystems. Besides being the most biodiverse area in Mexico, it has this water capture function, and the protected areas, especially the Montes Azules Biosphere Reserve, play a crucial role.

However, one of the main threats we have is a lack of control in the management of the reserve in the northwest part, which we call “the national tank” because there is a very extensive lagoon system. Lands around these lagoons have been invaded and deforested, so they require very serious intervention and a restoration process.

The other very important instrument already in place in the basin is that it was decreed as a water reserve, where the amount of water that can be used and how much is needed to maintain the wetlands of the lower basin—such as those of the Pantanos de Centla Biosphere Reserve in Tabasco—up to its mouth in the Gulf of Mexico was considered. Thanks to the reserve, productive processes with high water consumption can no longer be carried out, nor can the dam that would modify the water flow be built. Of course, there is always a risk that a decree could be overruled. That is why it is so important for society to understand and defend it.

We also need to restore water bodies to allow the hydrological cycle to function properly. Many streams and rivers are deforested and dry up in the dry season. With climate variation, this problem has aggravated. The work we are doing between UNAM’s Faculty of Sciences and Natura y Ecosistemas Naturales organization, together with farming communities, is to restore riparian vegetation. Furthermore, with training and environmental education actions, as well as the implementation of sustainable productive activities like ecotourism or agroforestry systems, deforestation is being stopped.

The region also has a problem with very intensive use of agrochemicals, which puts people’s health and water quality at risk. We are promoting agroecology to reduce agrochemical consumption.

 

Working group in the Lacandon Rainforest.

  Julia Carabias

UI: How effective is the agroecological perspective for sustainable development?
JC: I believe that agroecology in a region like this, strategic for its biodiversity and the water it generates, is indispensable. It is very complex because it requires a change in the production system and people’s vision, but it is also based on the experience of many indigenous peoples, and that is a great advantage. It requires accompaniment and subsidies because initially yields drop and more labor is needed. But in the long run, it is durable; the soil is not depleted, nor is water contaminated [see UNAM Internacional 3, pp. 90-107]. But who will pay for it? The farmer cannot. Government must subsidize productive conversion. It needs to be integrated as public policy and prioritized in specific areas; for me, these should be high biodiversity areas. We have very clearly identified in the country which are the areas of very high biodiversity, where indigenous farming communities are located and which are in poverty. It should become a state policy, and scientific evidence has shown its benefits.

Ciénega de Santa Clara en San Luis Río Colorado, Sonora

 AyuntamientoSLRC

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