Introduction: Global warming is one of the most critical challenges of the 21st century, with extensive implications for ecosystems, the environment, and human societies. Human activities such as fossil fuel consumption, deforestation, and industrial processes have led to a substantial increase in greenhouse gas concentrations in the atmosphere, resulting in global warming and a cascade of environmental effects. Understanding the impacts of global warming on the environment is crucial for developing effective mitigation and adaptation strategies. Therefore, research on topics such as global warming is of paramount importance.
Materials and Methods: This study utilized daily climatic data, including minimum and maximum temperatures, precipitation, and sunshine hours from 120 synoptic stations across Iran over 30 years (1993-2022). The Mann-Kendall test and Sen's slope estimator were employed to assess the trends in annual average temperature changes. To forecast future temperatures influenced by global warming, outputs from the CanESM2 model (from CMIP5 models) were used under two scenarios: RCP2.6 and RCP8.5. Given the large-scale outputs of these models, downscaling was necessary for station-level studies, and the LARS-WG model, one of the most widely used downscaling models, was applied.
Results: The results indicated a significant increasing trend in the annual average temperature of Iran, with a slope of 0.053 (p<0.05) during the base period. The most increasing trend was observed at Bostan and Qorveh, while the least was observed at Shiraz. Out of the 120 stations, 11 showed no significant trend, with only the Quchan station exhibiting a decreasing trend (not significant at the 5% level). Under the RCP2.6 and RCP8.5 scenarios, the annual average temperature in Iran is projected to reach 18.84 and 19.6°C during 2021-2040, 19.40 and 20.19°C during 2041-2060, 19.42 and 21.7°C during 2061-2080, and 18.88 and 22.99°C during 2081-2100, respectively. In the base period, the temperature range across all stations was between 8-28°C, while by the end of the century, the distribution of stations will shift towards higher temperatures, with no station experiencing an annual average temperature below 14°C under the RCP8.5 scenario. Spatially, southern regions will experience the most significant temperature increases, with average annual temperatures projected to rise to between 32 and 34°C by the century's end under the pessimistic scenario.
Discussion: The findings of this study indicate that the increasing trend in Iran's average temperature observed in recent years will continue in the future, albeit with variations across different climate scenarios. Therefore, appropriate planning can help mitigate the extent of the increase and potential damage. Given the impact of temperature on the environment, economy, and all aspects of human life, it is essential to address this issue to ensure risk management and informed decision-making are conducted with precision planning. The results of this research will assist managers and planners in implementing sustainable strategies for adapting to future conditions and enhancing resilience. The results of this study highlight a concerning trend of increasing temperatures in Iran due to global warming, emphasizing the urgent need for effective planning and adaptation strategies to mitigate its impacts on the environment and society.