Spatio‐Temporal Change of Climate Regions in Türkiye

ABSTRACT This study explores the climate zones' shift in Türkiye over time as a result of climate change, focusing on the period from 1954 to 2023. The analysis is based on high‐resolution ERA5‐Land reanalysis data and includes the record‐breaking temperature extremes of the past decade. Climate zones were identified using the Ward linkage method, a hierarchical clustering algorithm approach, applied across 10‐year moving windows within 30‐year periods. This approach revealed eight distinct homogeneous climate regions and allowed for tracking their changes in location and extent over time. To examine these clusters, the De Martonne aridity index was used to assess temporal and spatial variability. The results indicate a notable contraction of very humid and extremely humid regions, alongside the emergence of a new arid zone in Southeastern Anatolia. The proportion of semi‐arid areas increased significantly, from 9.03% in 1954–1983 to 14.62% in 1994–2023, highlighting a clear trend toward aridification. The changes in the zones were not uniform across the country. The Southeastern Anatolia, Mediterranean, Aegean, Marmara, and Central Anatolia geographical regions exhibit the most pronounced shifts, indicating region‐specific impacts of climate change. The findings demonstrate the growing influence of climate change on Türkiye's hydroclimatic regime, indicating a clear tendency toward aridification and supporting broader global projections of a northward expansion of the subtropical climate zone.