High-Level Opening Session of the IAEA Scientific Forum 2025: Atoms for Water

Excellencies, distinguished colleagues,

It is a distinct pleasure for me to speak at this session today – the WMO, the specialised UN agency for weather, climate and water, collaborates with the IAEA on application of isotopic techniques to better understand the coupled climate-water-human system and predict the behaviour of this system. This collaboration covers several cycles in the Earth System including water and carbon.  

The State of Global Water Resources in 2024, which will be launched later this week, tells us something striking:  

For six years in a row, only about one-third of world’s river basins have been within normal conditions; this is a sign of an increasingly erratic water cycle.  

. River flows, the lifeblood of   our economies and ecosystems are shifting beyond predictability.  

Floods swept through some regions, while others endured intense drought.  

Europe experienced its most severe flooding since 2013, with more than 335 lives lost and economic damages estimated at €18 billion. At the very same time, the Amazon Basin reached record-low water levels, leaving 1.2 million people struggling with shortages of water, food, and energy.

These are not distant or disconnected crises, they are two sides of the same coin: too much water in one place, too little in another.  

This is the reality of the climate emergency: water systems are increasingly uncertain and unpredictable. This is why, innovative methods including isotopic techniques are more important than ever.  

But the message today is not only about extreme events. It is about data, information and knowledge.  

Too much of the world’s water resources remains understudied, unmeasured, and therefore unmanageable.

Africa and Asia, together, account for just three per cent of the river discharge stations feeding into global assessments. The state of the soil moisture, essential to understand and cope with drought, is still scarcely observed. Groundwater, a hidden reserve, remains poorly monitored, even as aquifers decline under unsustainable demand.  

The message I want to convey today is simple and urgent:  we can close the water knowledge and management gap only by closing the data gap. Nuclear science, working alongside meteorology and hydrology, can help us do exactly that.

Isotope hydrology reveals where groundwater comes from, how old it is and whether it is being used faster than it is replenished.  

Rainfall and water vapour isotopic composition trace how precipitation forms, moves, and recharges aquifers. This is a vital knowledge for drought and flood management. Isotopic composition of greenhouse gases and organic materials help us understand soil-water interactions and carbon and water cycles.

Together with WMO’s global observing networks and forecasting systems, these techniques allow us   “to see the invisible” linking atmospheric water vapour to rainfall, rainfall to river flows and river flows to groundwater recharge. This is how nuclear science, in its most peaceful applications, supports humanity’s most vital resource: water.

What does this mean for action?  

First, we must scale up innovation. Techniques that are proven in a handful of countries must be made available to all, particularly to those most exposed to drought and flood risk.  

Second, we must embrace data sharing. The 2024 report shows that when more countries share data, understanding improves, and decisions are better informed. If we are serious about water, we must get serious about data.

Third, we must invest in capacity.  Reports inform, but action transforms. We need people skilled in using the latest technology and methods, including isotope hydrology.

At WMO, we are advancing the WMO Hydrological Observing System (WHOS) and the Hydrological Status and Outlook System (HydroSoS) which provide standardized, near real-time insights into water resources. Together with the IAEA, we should integrate isotope hydrology, rainfall and water vapour monitoring and carbon fluxes into these systems, creating a new level of global water intelligence.

Excellencies, the challenges are serious, but the path is clear.  

Improve monitoring. Integrate innovation. Share data. Build capacity to act.  

By joining the strengths of nuclear science with meteorology and hydrology, we can move from fragmented reactions to anticipatory water management. We can turn knowledge into resilience, ensuring that tomorrow’s generations inherit water security not water risk.

Thank you