Comments on "Mediterranean Drying by a positive North Atlantic oscillation trend over the last 65 years is an extreme outlier in the CMIP6 multimodel ensemble"

2026

Article référencé dans le Web of Science WOS:001753634100001

Vicente-Serrano S. M., Domínguez-Castro F., Beguería S., Halifa-Marin A., Lima M. M., Trigo R., Gimeno L., García-Herrera R., Lionello P., Brunetti M., Tramblay Yves, Maugeri M., Gonzalez-Hidalgo J. C., Zorin-Molina C., Cheval S.

Journal of Climate, 2026, 39 (10), p. 2829-2845 ISSN 0894-8755

This comment addresses the interpretation of recent findings reported by Seager et al., who identify widespread winter drying across the Mediterranean region during 1959-2023 and link this signal to a positive trend in the North Atlantic Oscillation (NAO), characterized as an extreme outlier in the CMIP6 multimodel ensemble. Given the strong interannual and multidecadal variability that typifies Mediterranean hydroclimate, we argue that these conclusions require careful reassessment within a broader temporal and dynamical framework. Using evidence from high-density homogenized station observations, instrumental NAO indices extending back to the early nineteenth century, CMIP6 historical and preindustrial control simulations, and multiple paleoclimate NAO reconstructions, we evaluate the robustness of both the reported precipitation and NAO trends. We show that the winter drying identified for the 1959-2023 period is highly sensitive to the choice of the starting decade and largely reflects the influence of anomalously wet conditions during the 1960s. When longer records are considered, Mediterranean winter precipitation is dominated by variability rather than by a persistent basinwide trend. Similarly, the positive NAO trend over the last 65 years is shown to be consistent with internal atmospheric variability. Comparable multidecadal NAO trends and decades with strongly negative NAO values occur repeatedly in unforced model simulations and in proxy-based reconstructions over the last several centuries, indicating that the recent evolution of the NAO is not exceptional in a long-term context. This comment emphasizes the importance of distinguishing short-term variability from long-term change when interpreting observational trends in highly variable regions. We stress that recent observations should not be overinterpreted as evidence of an unprecedented or forced shift in Mediterranean winter precipitation or NAO behavior.

Sciences fondamentales / Techniques d'analyse et de recherche [020] ; Sciences du milieu [021]

EUROPE ; ZONE MEDITERRANEENNE ; ATLANTIQUE NORD

Fonds IRD [F B010097061]

fdi:010097061