Downscaled CMIP6 climate projections for Mediterranean water management

The Mediterranean region is highly vulnerable to climate change, with increasing pressures on already limited water resources. Reliable and high-resolution climate projections are therefore essential to inform adaptation and mitigation strategies and to support integrated water resources management. Within the framework of the OurMED project (https://www.ourmed.eu), this study contributes to these objectives by providing long-term climate projections at both Mediterranean-wide and local scales.

The study presents projections of precipitation and temperature extending to the end of the 21st century, based on simulations from five CMIP6 General Circulation Models under two contrasting Shared Socioeconomic Pathways: SSP1-2.6 and SSP3-7.0. Due to the current lack of CMIP6-driven regional climate simulations covering the Mediterranean basin, a dedicated dataset obtained through statistically downscaling is employed. This dataset is developed using a hybrid framework that combines convolutional neural networks with quantile delta mapping and spans an extended Mediterranean region. The resulting Mediterranean-scale projections are subsequently downscaled using quantile delta mapping to the eight OurMED demo-sites, which represent diverse climatic and socio-environmental conditions across Europe, North Africa, and the Middle East.

At the Mediterranean scale, the projections indicate a clear and spatially coherent warming signal throughout the century, with magnitude strongly dependent on the emissions pathway. Under SSP3-7.0, mean annual temperatures increase steadily across the basin, with end-of-century anomalies frequently exceeding 4°C in southern and eastern Mediterranean regions. In contrast, under SSP1-2.6, warming is substantially reduced and tends to stabilize after mid-century. These large-scale patterns are consistently reflected at the demo-site level. Under SSP3-7.0, all sites experience pronounced warming, with the strongest increases—on the order of 4–6°C by the end of the century—projected for southern and eastern Mediterranean sites such as Mujib (Jordan), Medjerda (Tunisia), and Sebou (Morocco). Central Mediterranean sites, including Albufera (Spain), Arborea (Italy), and Konya (Turkey), also show substantial warming, while northern sites such as Bode (Germany) and Agia (Greece) exhibit comparatively smaller temperature increases. Under SSP1-2.6, warming is consistently lower across all sites and generally levels off after mid-century.

Precipitation projections exhibit greater spatial heterogeneity and inter-model variability than temperature. At the Mediterranean scale, northern regions show relatively stable annual precipitation, whereas large parts of the central, southern, and eastern Mediterranean display a tendency toward drying, particularly under SSP3-7.0. This signal is reflected at the demo-sites, where northern and more humid locations, especially Bode (Germany), show limited changes, while most southern and eastern Mediterranean sites—including Albufera (Spain), Arborea (Italy), Medjerda (Tunisia), Sebou (Morocco), and Mujib (Jordan)—experience decreasing annual precipitation, exacerbating water scarcity risks.

In addition to changes in mean climate conditions, a set of ETCCDI climate extreme indices is computed at the demo-site level to assess projected changes in temperature and precipitation extremes. Combined with seasonal analysis, these indicators provide a more comprehensive assessment of future hydroclimatic risks and support informed water resources management across the diverse environments represented by the OurMED demo-sites.

This work was supported by OurMED PRIMA Program project funded by the European Union’s Horizon 2020 research and innovation under grant agreement No. 2222.