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Water is a vital resource facing unprecedented global challenges due to climate change and population growth. In the webinar “The challenge of rivers and oceans: human impact on water,” Carlos Duarte, a leading marine ecologist, highlights the interconnected nature of the global water system, where oceans play a central role in the water cycle by supplying over 85% of evaporation that fuels precipitation. He stresses that current water management often treats freshwater and marine water separately, ignoring their crucial interactions. Human activities have disrupted natural water flows through pollution, excessive fertilizer use, and groundwater over-extraction, causing ecological damage such as ocean “dead zones” and aquifer depletion. Climate change exacerbates these issues by intensifying droughts and floods. Duarte advocates for integrating oceans into water policies and leveraging technologies like desalination and wastewater reuse to ensure sustainability.
Duarte emphasizes innovation as key to water sustainability, promoting a circular water economy, nature-based solutions, and renewable energy integration in water processes. He highlights advances in desalination, atmospheric water capture, and green hydrogen production, alongside the restoration of ecosystems like mangroves to improve water quality. Education, awareness, and equitable water governance are critical to fostering responsible use and equitable access. Duarte also calls for shifting food consumption patterns toward lower water-footprint foods like seafood and implementing water footprint labeling to inform consumers. Spain serves as a model for water innovation, combining technology and policy to address desertification and droughts. Ultimately, Duarte stresses that a holistic approach combining technology, ecosystem restoration, education, and collaborative governance is essential to securing water as a universal right amid climate uncertainty.
Carlos Duarte, one of the world's leading authorities on marine ecology, breaks down the consequences of human impact on rivers and oceans, and presents solutions based on innovation and sustainability to face the global water crisis
Water is essential for life and we face unprecedented challenges in ensuring its availability globally. In the webinar “The challenge of rivers and oceans: human impact on water“, Rut Bosque presents the main conclusions of the report Water, our vital resource in check. This document, prepared with contributions from more than 40 international experts, highlights key strategies to ensure water sustainability in a world affected by climate change and population growth.
Key recommendations include:
- Adopting a circular water economy: with a focus on reuse and efficiency to reduce waste.
- Implementation of technologies adapted to the local context: solutions designed to maximize impact according to the specific needs of each region.
- Promotion of sustainable practices in sectors with high water demand: especially in agriculture, the textile industry and data centres, which are large consumers of water.
- Integration of renewable energy into key processes: such as desalination and water reuse, to reduce dependence on non-renewable sources.
- Promotion of education and social awareness: initiatives that strengthen the responsible use of water at all levels of society.
- Strengthening effective water governance: through clear, robust and transparent regulations that ensure efficient and equitable management.
Carlos Duarte, Tarek Ahmed Juffali Research Professor in Red Sea Ecology at King Abdullah University of Science and Technology (KAUST), a leading researcher in marine ecology and author of the foreword to the report, is the protagonist of our webinar today and underlines during the event the urgent need to address these challenges, which he breaks down and explains to us.
If you want to watch the webinar, you can do so here:
Human impact on rivers and oceans: Carlos Duarte analyzes the future of water
Water, an interconnected system
Carlos Duarte opens his speech with a forceful statement: “Water does not understand borders”. This resource flows dynamically between oceans, atmosphere and land, composing a global system where all elements are deeply interconnected. Despite this reality, water management policies and strategies often treat water as if it were an isolated resource, segmenting the conversation into freshwater or marine water, without considering their interactions.
The oceans, the engine of the water cycle: Duarte explains that the ocean is the largest reservoir of water on the planet, with approximately 97% of the total volume. Its relevance in the water cycle is fundamental, since more than 85% of evaporation comes from the seas. This vapor is transported through the atmosphere and returns to the earth in the form of precipitation, feeding rivers, aquifers, and terrestrial ecosystems. However, this critical connection is often ignored in water management policies.
- The residence time of water: Duarte details that water can remain in the ocean for thousands of years, while in the atmosphere its transit is much faster, in days or weeks. This dynamic equilibrium defines the availability of fresh water, which depends on processes such as condensation, precipitation, and runoff.
Impacts of human activities on water flows: The natural water cycle not only transports H₂O, but also nutrients, particles, and pollutants. Duarte highlights how human activities have altered these flows:
- Pollutants in freshwater: agricultural and urban waste, rich in nutrients such as nitrates and phosphates, reach rivers and end up in the oceans, causing phenomena such as eutrophication.
- Altering ocean density: The mixing of freshwater and marine water modifies the chemistry of the ocean and also affects its ability to transport heat, a crucial factor in regulating the global climate.
The ocean as the final receiver: For centuries, the oceans have been treated as humanity’s “ultimate sewer.” From the first sewage systems in Rome to modern urban infrastructure, rivers have served as conduits for transporting waste to the sea. Duarte shows how this unsustainable use has led to the emergence of “dead zones” in the oceans; areas where low oxygen concentration makes marine life impossible. On the other hand, Duarte points to the excessive use of synthetic fertilizers as one of the biggest problems, highlighting examples such as the Mar Menor. It proposes reducing fertilization in soils already overloaded with nutrients.
The most paradigmatic example is the Gulf of Mexico, where excess fertilizer from the Mississippi River has created one of the largest dead zones in the world. This phenomenon, in addition to affecting biodiversity, also affects the local economy, particularly fishing.
Impacts of climate change on the water cycle: Global warming is altering precipitation patterns, intensifying droughts and extreme rainfall. Duarte points out that recent phenomena, such as the unprecedented drought in the Amazon and catastrophic floods in the Mediterranean, are signs of an increasingly extreme water cycle.
The aquifer crisis: The overuse of groundwater has led to subsidence in cities like Jakarta, where the ground sinks as far as four meters in some areas. Duarte highlights that in countries such as Saudi Arabia, the depletion of fossil aquifers has forced a transition to desalination as the main source of water.
Integrating the oceans into water management: Duarte stresses that any sustainable strategy must recognize the role of the oceans in the water cycle. For example, the Water
In short, water, in all its forms, is a unique and interconnected system. Ignoring the relationship between oceans and freshwater limits our ability to address the water crisis and puts marine and terrestrial ecosystems at risk. Duarte closes this part of his presentation with an appeal to policymakers: “Water sustainability depends on our ability to see the system as a whole and act accordingly.”
Innovation for water sustainability
During the webinar, Carlos Duarte addresses several lines of technological and scientific innovation that have the potential to transform water management. These solutions seek to address the immediate challenges of scarcity and pollution while aiming to build resilient and sustainable systems in the long term.
1. Circular water economy: Duarte highlights that moving towards a circular water economy is crucial to reduce waste and maximize reuse. This includes the reuse of wastewater: treating it for use in agricultural irrigation, industry, or human consumption can significantly reduce the pressure on freshwater sources. This approach is already applied in countries such as Israel and Singapore, where more than 80% of treated water is reused. In Spain, the Region of Murcia reuses more than 90% of its water.
2. Innovation in desalination and atmospheric water capture
Desalination: Although this technology has been available for decades, recent advances have made it possible to reduce its environmental impact and energy cost. In places like Saudi Arabia and Spain, it has become an essential solution to ensure water supply in arid areas. However, Duarte stresses the need to properly manage the waste generated, such as brine, to minimise damage to the marine ecosystem.
Atmospheric water capture: This emerging approach uses technologies capable of extracting water even in regions with low humidity, an ideal solution for remote communities or areas of high aridity.
3. Energy production from water: Duarte emphasizes that water is not only crucial for life, but also for energy. The production of
4. Nature-based solutions: Restoring ecosystems such as mangroves, salt marshes, and seagrass meadows improves biodiversity and offers direct benefits on water quality. These ecosystems act as natural filters, reducing pollutants and improving resilience to floods and droughts.
5. Governance and international collaboration: Duarte stresses that no technological advance will be effective without clear regulatory frameworks and collaboration between governments, companies and communities. Spain, for example, has made progress in integrating renewable energy into water management processes and in the construction of desalination plants, but it still faces significant challenges in terms of governance and sustainability.
6. Changes in the food model: an innovative approach to reduce the global water footprint is to modify eating patterns. Duarte highlights that seafood has an almost zero water footprint compared to products such as meat or tropical crops, which require large amounts of water. Encouraging seafood consumption can free up water resources for other uses and contribute to a more sustainable food system.
Chocolate and beef are among the foods with the highest water footprint, reflecting the high consumption of water required for their production. According to the Water Footprint Network, producing one kilogram of chocolate requires around 17,000 liters of water, mainly due to intensive cocoa cultivation. Beef, on the other hand, needs approximately 15,400 liters of water per kilogram, since its production includes the water used to feed and maintain livestock. These figures highlight the need to consider the water impact of certain foods, especially in regions where water is a limited resource.
The landscape of water innovation is therefore vast and multifaceted. As Duarte stresses, the combination of technological advances, ecosystem restoration, and social and cultural changes is essential to ensure a resilient and sustainable water future. These solutions, many of which are already in place, need to be scaled up and integrated to address global water challenges.
Q Reflections for the Future
The Q segment of the webinar offers the opportunity to further explore the topics addressed by Carlos Duarte, enriching the discussion with new perspectives and concerns. It addresses specific questions on how to implement the strategies presented, as well as the social and technological challenges to ensure a sustainable water future.
The role of emerging technologies in water management: One of the questions raised revolves around the potential of emerging technologies to solve water availability and quality challenges. Duarte emphasizes that innovations must be adapted to the local context. For example, desalination, a viable solution for arid coastal areas, requires investments in renewable energy to be sustainable. In contrast, in agricultural regions, humidity sensors and artificial intelligence can optimize water use without large investments in infrastructure.
How to ensure equitable access to water: Several attendees express concern about inequality in access to water resources, especially in rural or marginalized communities. Duarte recognizes that this is one of the biggest challenges, even in developed countries. It proposes to promote decentralized models of water treatment and distribution, allowing local communities to manage their resources autonomously and resiliently.
Education and awareness as drivers of change: a recurring theme is the role of education in water sustainability. Duarte stresses that awareness campaigns must combine clear messages with impactful data. For example, showing how the consumption of certain foods directly affects the availability of water can transform habits. In addition, it suggests including water sustainability as part of educational plans at all levels, from basic education to university.
The Ocean-Freshwater Connection in Public Policy: A Key Question explores how to integrate ocean management into water resources strategies. Duarte argues that the oceans should be recognized as a fundamental part of the water cycle. This includes controlling pollutant discharges from rivers and promoting the sustainable use of marine resources as a source of desalinated water. It also proposes that public policies jointly address the health of terrestrial and marine ecosystems.
Spain as a laboratory for water innovation: in relation to the Spanish case, several attendees are interested in how the country could lead global water innovation. Duarte points out that Spain, with its challenges of desertification and droughts, has the potential to become a benchmark. Pioneering projects such as the integration of renewables in desalination plants and the use of advanced technologies in agricultural management are examples of how the country can export solutions internationally.
The impact of climate change and future projections: finally, Duarte addresses the role of climate change in the intensification of the water crisis. It highlights that extreme events, such as floods and droughts, will be more frequent, requiring adaptive planning. This includes building more resilient infrastructure, investing in highly accurate climate predictions, and creating emergency funds to respond quickly to water catastrophes.
Duarte makes it clear that, although the challenges are enormous,
The combination of innovation, education and collaborative action can make all the difference in the fight to guarantee water as a universal right.
