New research identifies the key causes of changes affecting river deltas around the world and warns of an urgent need to tackle them through climate adaptation and policy.
Deltas are low-lying areas that form as rivers and empty their water and sediment into another body of water, such as an ocean, lake, or another river.
Some of the largest in the world, such as the Rhine, Mekong, Ganges-Brahmaputra-Meghna, and Nile, are threatened by climate change, facing rising sea levels and increasing frequency of extreme events.
With approximately 500 million people today living within or adjacent to delta systems, this is a major issue.
To address this, a team of international scientists has developed a new framework that identifies the 10 main drivers of change in deltas globally. These are: climate change, sea level rise, deforestation, intense agriculture, urbanisation, impoundments, land subsidence, ground water extraction, flood defences, and resources mining.
Most local, human-induced causes show measurable impacts within years and the framework provides a clear basis for prioritising timely, locally grounded action with a deeper understanding of the systems that shape these complex and dynamic environments.
Publishing their findings today in Nature Climate Change, the team includes scientists from the Universities of East Anglia (UEA), Southampton and Oxford in the UK, and Deltares, TU Delft, Wageningen University and Utrecht University in The Netherlands.
“Deltas are the most complex coastal systems in the world and recognising these multiple drivers and how they operate in each delta is fundamental to finding solutions,” said co-author Prof Robert Nicholls, from the Tyndall Centre for Climate Change Research at UEA and the University of Southampton.
Effective adaptation requires more than isolated measures, that often overlook an important step in deeper assessments of the system as a whole.
The diagnostic framework links these drivers of change with their direct and indirect impacts across scales in time and space (divided in centuries, decades or temporal scales). It is intended to support policymakers, technocrats, engineers, and stakeholders in developing locally grounded adaptation strategies that are both realistic and resilient.
It aims to help identify and understand the interconnectivities within the biophysical system, from source to sink, and how these link with local/regional/transboundary socio-economic structures.
While climate change threatens the world’s deltas, anthropogenic drivers – largely reflected in sediment starvation and resource extraction, profound land-use change and hydrological regime shifts – can outpace climate change in the short to medium term.
Nearly all local anthropogenic drivers result in measurable impacts within years or decades, emphasising the significance and relevance of local and regional causes for effective and timely climate adaptation and policy development.
“If we want to give deltas a real chance at long-term climate resilience, we need collective comprehension of the human footprint and the underlying drivers of change,” said Dr Sepehr Eslami, lead author and coastal expert at Deltares.
“By promoting system-level thinking, this framework encourages more critical and collaborative approaches to adaptation. It helps identify the solutions with the highest chance of being implemented successfully, especially when embedded in a longer-term vision.”
The diagnostic framework can also foster constructive dialogue among stakeholders and ensure that adaptation efforts are both science-based and socially relevant.
“Decision making in delta systems is extremely difficult due to all the complex interactions between different processes,” added Dr Amelie Paszkowski from the University of Oxford.
“But this framework helps to disentangle these dynamics and diagnose the challenges in a delta, which is a fundamental first step in defining adaptation solutions that tackle the root causes of the impacts felt.”
The research was inspired by the work of the Rise and Fall Project, a collaboration between Deltares and the Utrecht University, and also involved researchers from the University of Cologne and University of Padova.
Over a period of nearly three years, the team combined decades of knowledge on vulnerabilities in deltas and adaptation efforts to develop a framework that can facilitate diagnosing the key processes and interactions shaping a delta system. The goal: to offer a holistic foundation for planning effective, context-sensitive adaptation strategies.
‘A systems perspective for climate adaptation in deltas’ is published in Nature Climate Change on July 7.
Notes
- The paper DOI is: 10.1038/s41558-025-02368-0.
- Once published online, the paper will be available at the following URL: https://www.nature.com/articles/s41558-025-02368-0
- The University of East Anglia (UEA) is a UK Top 25 university (Complete University Guide and HESA Graduate Outcomes Survey). It also ranks in the UK Top 20 for research quality (Times Higher Education REF2021 Analysis) and the UK Top 10 for impact on Sustainable Development Goals. Known for its world-leading research and good student experience, its 360-acre campus has won seven Green Flag awards in a row for its high environmental standards. The University is a leading member of Norwich Research Park, one of Europe’s biggest concentrations of researchers in the fields of environment, health and plant science. www.uea.ac.uk