Global warming and anthropogenic climate change have profoundly altered the long‑term patterns of temperature and precipitation across the planet, driving substantial modifications in the spatial distribution of climatic zones and generating far‑reaching environmental, ecological, and socio‑economic consequences. Iran, located within the arid and semi‑arid belt of the Northern Hemisphere, is particularly vulnerable to these changes due to its complex topography, diverse climatic regimes, and high sensitivity to temperature and precipitation variability. Accordingly, this study aims to detect climate change signals in Iran by examining the displacement of the country’s climatic zones during the historical period (1901–2020) and the projected near‑future (2041–2070) and far‑future (2071–2099) periods. To achieve this objective, seven high‑resolution climate datasets constructed using observational records and elevation‑based corrections were employed to evaluate historical climatic variability and long‑term trends. These datasets offer a spatial resolution of 0.01°, enabling a detailed representation of Iran’s heterogeneous climatic landscape. For future projections, precipitation and temperature outputs from CMIP6 global climate models were utilized under three Shared Socioeconomic Pathways (SSP1‑2.6, SSP2‑4.5, and SSP5‑8.5). These scenarios represent a wide spectrum of possible future trajectories, ranging from sustainable development and low emissions to high emissions and intensive fossil‑fuel use. The integration of these datasets allowed for the generation of Köppen-Geiger climate classification maps for four historical sub‑periods (1901–1930, 1931–1960, 1961–1990, and 1991–2020) as well as for the near‑ and far‑future periods. Subsequently, the percentage of climatic zone displacement in each period relative to the baseline period (1961–1990) was calculated and analyzed to quantify the extent of climatic transformation.

Results indicate substantial shifts in climatic groups across Iran, particularly in the mountainous regions of the west and north, where snowy and temperate climates have been replaced by warmer and drier types. In central and eastern Iran, cold desert climates have markedly retreated in favor of warm desert climates. Future projections similarly reveal an expansion of warm desert climates in central Iran and a pronounced tendency toward desertification in the northwest. Climatic shifts in the near‑future period especially under the high‑emission scenario SSP5‑8.5 are considerably more extensive than those observed during 1991–2020. Comparisons between future and historical maps show a widespread retreat of snowy climates and their replacement by Mediterranean temperate climates in the west and north, a transition from cold semi‑arid to warm semi‑arid climates across large portions of the western and northeastern highlands, and a significant expansion of warm desert climates in the northwestern and northeastern mountainous regions. These changes intensify substantially in the far‑future period, such that under SSP5‑8.5, snowy climates in western Iran nearly disappear or become confined to the highest mountain peaks, signaling a profound alteration of the country’s hydrological and ecological systems. The intensification of warm desert climates across central, northwestern, and northeastern Iran suggests that large portions of the country may face heightened risks of desertification, reduced water availability, and increased vulnerability to extreme climatic events. These findings underscore the urgent need for adaptive strategies and climate‑resilient planning to mitigate the potential impacts of these projected changes.

Overall, this study provides a detailed and high resolution assessment of climatic zone displacement in Iran over both historical and future periods. By integrating observational datasets with CMIP6 projections and applying the Köppen-Geiger classification system, the research offers valuable insights into the spatial dynamics of climate change in a highly vulnerable region. The results highlight the accelerating pace of climatic transformation in Iran and emphasize the importance of proactive adaptation measures to address the environmental and socio economic challenges posed by a rapidly changing climate.