Possible Scenarios of Winter Wheat Yield Reduction of Dryland Qazvin Province, Iran, Based on Prediction of Temperature and Precipitation Till the End of the Century

The climate of the Earth is changing. The Earth’s temperature is projected to maintain its upward trend in the next few decades. Temperature and precipitation are two very important factors affecting crop yields, especially in arid and semi-arid regions. There is a need for future climate predictions to protect vulnerable sectors like agriculture in drylands. In this study, the downscaling of two important climatic variables—temperature and precipitation—was done by the CanESM2 and HadCM3 models under five different scenarios for the semi-arid province of Qazvin, located in Iran. The most efficient scenario was selected to predict the dryland winter wheat yield of the province for the three periods: 2010–2039, 2040–2069, and 2070–2099. The results showed that the models are able to satisfactorily predict the daily mean temperature and annual precipitation for the three mentioned periods. Generally, the daily mean temperature and annual precipitation tended to decrease in these periods when compared to the current reference values. However, the scenarios rcp2.6 and B2, respectively, predicted that the precipitation will fall less or even increase in the period 2070–2099. The scenario rcp2.6 seemed to be the most efficient to predict the dryland winter wheat yield of the province for the next few decades. The grain yield is projected to drop considerably over the three periods, especially in the last period, mainly due to the reduction in precipitation in March. This leads us to devise some adaptive strategies to prevent the detrimental impacts of climate change on the dryland winter wheat yield of the province

Modelling Climate Change Impact on Irrigation Water Requirement and Yield of Winter Wheat (Triticum aestivum L.), Barley (Hordeum vulgare L.), and Fodder Maize (Zea mays L.) in the Semi-Arid Qazvin Plateau, Iran

It is very important to determine the irrigation water requirement (IR) of crops for optimal irrigation scheduling under the changing climate. This study aimed to investigate the impact of climate change on the future IR and yield of three strategic crops (winter wheat, barley, fodder maize) in the semi-arid Qazvin Plateau, Iran, for the periods 2016–2040, 2041–2065, and 2066–2090. The Canadian Earth System Model (CanESM2), applying IPCC scenarios rcp2.6, rcp4.5, and rcp8.5, was used to project the monthly maximum and minimum temperatures and monthly precipitation of the region. The results indicated that the maximum and minimum temperatures will increase by 1.7 °C and 1.2 °C, respectively, under scenario rcp8.5 in the period 2066–2090. The precipitation will decrease (1%–13%) under all scenarios in all months of the future periods, except in August, September, and October. The IR of winter wheat and barley will increase by 38%–79% under scenarios rcp2.6 and rcp8.5 in the future periods. The increase in the IR of fodder maize will be very slight (0.7%–4.1%). The yield of winter wheat and barley will decrease by ~50%–100% under scenarios rcp2.6 and rcp8.5 in the future periods. The reduction in the yield of maize will be ~4%. Serious attention has to be paid to the water resources management of the region. The use of drought-tolerant cultivars in the region can be a good strategy to deal with the predicted future climatic conditions

Recent trends in vegetation cover and phenology in the southern Mediterranean region: Potential impacts on crop production and its link to changing climate extremes.

The southern Mediterranean region stands as one of the most vulnerable areas to climate change and variability in the world. There is a need for further understanding of the complex interactions between climate, vegetation, and crops to fully understand the combined impacts of extreme climate events on the agriculture sector. Using daily Normalized Difference Vegetation Index (NDVI) data, we evaluate recent trends across 15 vegetation phenology indicators between 1982 and 2019. Subsequently, we analyse potential links between recent trends in vegetation phenology and land-use land-cover. We found significant increasing trends in Maximum Value of NDVI (MaxV), length of growing season (LengthGS), and the time between the occurrence of the onset and maximum value (AreaB), especially within croplands. We also noted these vegetation phenological indicators, and their associated changes in the last 38 years, are significantly correlated with an increase in regional crop production. Then, we conducted a comprehensive seasonal trend analysis of extreme (potentially compound) climatic stresses and discussed how it aligns with recent trends in MaxV and LengthGS. We found that extended LengthGS and increased MaxV are consistent with increased precipitation and cooler temperatures during spring and summer, coupled with warmer autumn and winter trends. These trends collectively mitigate extreme heat, water, and compound heat-water stresses, contributing to improved crop yields over the region. By improving our understanding of the potential impacts of recent climate change on vegetation phenology, crop production and land use, our findings can help providing guidance for more informed decision-making and adaptation strategies in the southern Mediterranean region