Temperature projections over Iran during the twenty-first century using CMIP5 models

Abstract

A 13-member ensemble from CMIP5 is used to analyze the Iran future climate in terms of surface air temperature (TAS), identifying when anomalies of 1.5 ℃, 2.0 ℃ and 2.5 ℃ would be achieved respect to the preindustrial period (1861–1900) using the time sampling method. The global warming targets ( $${D}_{1.5}, {D}_{2.0}, {D}_{2.5}$$ ) are attained by the 2024, 2040 and 2056 under the RCP4.5 scenario, on the other hand, the respectively, attained years for Iran are 2023, 2036 and 2051, an evidence of a higher mean increase in surface air temperature respect to the global behavior. We identified important aspects regarding to temperature anomalies in the Iran region: (1) A mean warming of 1.0 ℃ for the 2001–2010 decade respect to the preindustrial baseline. (2) A mean warming of 0.5 ℃ for the 1960–2005 period respect to the preindustrial period. (3). For the 2006–2100 period under RCP4.5 scenario, was possible to identify a warming trend ( $$0.028 {^\circ{\rm C} } {\mathrm{year}}^{-1}$$ ), which is above double the trend observed in the period 1960–2005 ( $$0.012 {^\circ{\rm C} } {\mathrm{year}}^{-1}$$ ). 4) Largest trends over Iran occur for the 2006–2050 period (2.75 ± 0.74 to 4.72 ± 0.82 °C/century) respect to the 2006–2100 period (2.28 ± 0.36 to 3.39 ± 0.37 °C/century) with the most possible reason associated with the fact that under the RCP4.5 scenario, the emission rate increases toward 2040 and then stabilizes to the end of the century. All of these indicators evidence an intensification of the warming over the Iran region respect to the global trends. From the spatial analysis of surface air temperature trends over 5 regions of Iran for the 1850–2005, 1960–2005, 2006–2050 and 2006–2100 periods was possible to identify a significant increase in all the trends over Iran, but specially in the Southwestern of the country with a warming rate higher in warm regions than the cold climate regions. The present study reveled that further research should be development to explore renewable energy and create mitigation plans to minimize greenhouse gas emissions to overcome the increased risk of climate change effects.