Analysis of Climatic Zones and the Danger of Desertification in Karun Basin under Climate Change Conditions using UNEP Index

The excessive emission of greenhouse gases in recent decades and the ongoing changes in the climate have changed the meteorological parameters and, accordingly, the climatic zones. In this study, the future prospect of climatic zones and the risk of desertification in the watershed of Karun basin was investigated using UNEP index and LARS-WG6 microdirection model and HadGEM2-ES model under the RCPs emission scenarios for three periods 2021-2040, 2041-2060, and 2061-2080. The results pertaining to all three future periods and RCPs release scenarios showed that the long-term average annual precipitation will decrease between 1.9 and 14.6% compared to the base period, but the annual average minimum temperature will be between 1.2 and 3.4 °C, maximum temperature between 1.3 and 3.7 °C and the annual average of evaporation and transpiration will increase between 4.7 and 12.3% compared to the observation period. In the upcoming period and based on the emission scenarios, dry climate (the risk of very severe desertification) and semi-arid climate (the danger of severe desertification) increase 3.5% and 4.4%, respectively, and semi-humid (moderate desertification) and humid (no desertification) and very humid (moisture and wet climate) decrease 4% and 4.7%, respectively. However, semi-humid climate zones (low risk of desertification) with 0.8% will be less severe. Under the pessimistic scenario, the semi-arid climate region will reach its maximum level among the publishing scenarios in the near future with 12.4%. Therefore, this displacement in the boundaries of climatic classification will increase the desertification of Karun basin in the upcoming period.