For years, scientific reports and discussions have painted a picture of the Mediterranean as a region steadily drying out, with less and less rainfall over time. A major new study published in Nature suggests that the reality is far more complex. With contributions from Associate Professor Aristeidis Koutroulis of the Technical University of Crete, a REACT4MED partner, the research takes a deep look at long-term rainfall records and challenges the idea of a simple downward trend.

The study analysed precipitation data covering the period 1871 to 2020, using an extraordinary dataset of more than 23,000 ground stations across 27 Mediterranean countries. This makes it one of the most comprehensive investigations of rainfall patterns in the region to date. What the team found is striking: rather than showing a steady decline, Mediterranean rainfall has largely remained stable over the past 150 years. Rainfall is still highly variable: wet decades are followed by drier ones, however when viewed as a long-term trend, there is no consistent decrease.

To reach these conclusions, the researchers, led by Sergio Vicente-Serrano, compared the observational record with simulations from the leading climate model projects, CMIP5 and CMIP6. Both the historical data and the climate models now align in showing that the rainfall story is not one of ongoing decline. Instead, the fluctuations we see are mostly driven by changes in atmospheric circulation and by the natural variability of the climate system itself.

This finding does not mean that the Mediterranean is safe from climate stress. Even though rainfall has remained stable, temperatures across the region have risen sharply. This warming leads to higher evaporation rates, which in turn increase aridity and strain water resources. In practice, that means that farmers, communities, and ecosystems are still facing the very real challenges of a hotter, drier environment, even if rainfall itself has not dropped as much as previously assumed.
Professor Koutroulis highlights the importance of the work, noting that robust, open-access, in situ data, meaning long-term ground measurements, are essential. They allow scientists to untangle the complexities of climate variability and, just as importantly, give decision-makers the reliable evidence they need to manage agriculture, water resources, and environmental strategies effectively across the Mediterranean.

By reconciling historical measurements with state-of-the-art climate models, this study challenges a long-standing narrative and provides a clearer, more nuanced understanding of what is happening to rainfall in the region. Rather than a story of continuous decline, the Mediterranean climate is one of variability, driven by complex patterns in the atmosphere and amplified by rising temperatures. That insight is vital for shaping the environmental and economic strategies of the decades ahead.

The complete study is available online in Nature: https://rdcu.be/edntf.