Abstract

A 22-member ensemble from CMIP6 is used to analyze the Iran future climate in terms of surface air temperature, identifying when anomalies of 1.5 °C, 2.0 °C, and 2.5 °C would be achieved with respect to the preindustrial period (1861–1900). Validation was conducted using data from 97 stations of IRIMO around Iran in the 1990–2014 period, and the following range metrics were obtained: 1.45–3.49 (MAE), 1.82–3.99 (RMSE), and 16.51–38.04 (MAPE); however, ACCESS-ESM1.5, ACCESS-CM2, CESM2-WACCM, BCC-CSM2-MR, FGOALS-g3, INM-CM5-0, and CNRM-CM6-1-HR models display the best performance. The global warming targets (D1.5,D2.0,D2.5) are attained by the 2019, 2029, and 2047 under SSP1-2.6 scenario; 2017, 2031, and 2043 under SSP2-4.5 scenario; and 2016, 2028, and 2039 under SSP5-8.5 scenario; on the other hand, the respectively attained years for Iran are 2007, 2019, and 2030 under SSP1-2.6 scenario; 2007, 2016, and 2028 under SSP2-4.5 scenario; and 2006, 2015, and 2027 under SSP5-8.5 scenario, an evidence of a higher mean increase in surface air temperature with respect to the global behavior. We identified important aspects regarding the temperature anomalies in the Iran region: (1) a mean warming of 0.64 °C (SSP1-2.6), 1.47 °C (SSP2-4.5), and 0.74 °C (SSP5-8.5) for the 2000–2024 period with respect to the preindustrial baseline; (2) a mean warming of 0.82 °C (SSP1-2.6), 2.06 °C (SSP2-4.5), and 0.76 °C (SSP5-8.5) for the 1960–2014 period with respect to the preindustrial period; (3) a warming trend of 2.88 ∘Ccy−1 for the 1960–2014 period, more than the triple of the trend for the 1850–2014 period of 0.54∘Ccy−1; and (4) for the 2014–2100 period, it was possible to see warming trends of 1.34∘Ccy−1(SSP1-2.6), 3.36∘Ccy−1(SSP2-4.5), and 7.46∘Cyr−1(SSP5-8.5), which represent trends above double the trend observed in the 1960–2014 period under the SSP5-8.5 projection scenario. All of these indicators show an intensification of the warming over the Iran region with respect to the global trends. From the spatial analysis of surface air temperature trends over five regions of Iran for the 1850–2014, 1960–2014, 2014–2050, and 2014–2100 periods, it was possible to identify a significant increase in all the trends over Iran but specially in the central part of the country.