Investigating the impact of climate change on changes in the cultivated area of selected agricultural products in Jiroft Plain

Introduction

The climate has played a role in the collapse of most human civilizations and even the historical-geographical evidence shows that most of the great and stable civilizations were formed in certain geographical-climatic areas that had a suitable biological condition. Even the unfavorable climatic conditions have sometimes made human civilizations face serious damages and pushed them towards collapse. In other words, the existence of most human civilizations can be attributed to climatic conditions, and even citing historical-geographical evidence, especially the special environmental condition of the world in the current situation, it can be claimed that probably the countries that are related to biological issues economic, social and even political do not attach special importance to this issue, especially in a situation where the climatic conditions of the world are accompanied by vast changes day by day, in the not too distant future with severe problems in various dimensions. They will be faced with economic problems, which can even threaten their existence. With the increasing growth of the world's population and the need of human societies for energy and the use of other types of fuels in today's industrial world, like other parts of this earth, the climate and the atmosphere of the earth also suffer from injuries, damages and the effects of disasters. The human burden has not been spared and has been affected by many fundamental changes, of which the phenomenon of climate change is one of the clear examples. The most important indicators of climate change are temperature and precipitation, the change of each of which factors causes' climate variability, the consequences of which also change people's lives. The increase of greenhouse gases and suspended particles in the atmosphere as well as the variability of the earth's surface are among the most obvious consequences and damages of the world's industrial activities and human societies in the past two centuries. This phenomenon has different effects on different economic sectors such as agriculture, industry, tourism, water and health. Therefore, according to what has been said, it can be concluded that climate change as a phenomenon will inevitably happen in Iran. The occurrence of such a thing will be a fundamental issue for the agricultural sector, considering the climatic situation, hydrological characteristics and the limitations of the country's agricultural sector. It has created a special climatic situation for the country of Iran due to its location in the middle latitude. First of all, due to the high-pressure rule of the tropical zone, the total amount of precipitation in Iran is low. Secondly, the relatively warm climate has dominated the country due to the expansion of Iran between 25 – and 10-degree north latitude.



Material and Methods

One of the models that are used for exponential micro-scale GCM models is the LARS-WG model. This model is one of the best for generating random weather data, which is used to generate rainfall, radiation, and maximum and minimum daily temperatures in a station for the current and future climate. The LARS-WG model uses complex statistical distributions to model meteorological variables. The length of dry and wet periods, daily precipitation and radiation series, and semi-empirical distribution are the basis of this model for modeling. Climatic parameters of minimum temperature, maximum temperature, precipitation and solar radiation are the inputs of LARS-WG model, which are all in the daily time frame. In this model, the radiation is modeled independently of the temperature, and the sundial can be used instead. From the semi-empirical distribution of the rainfall of the month in question and independent of the wet series with the amount of precipitation in the previous day, the amount of precipitation of one day is calculated. In this model, the temperature is estimated by Fourier series. The daily minimum and maximum temperatures are modeled as random processes with the average and standard deviation of the daily standards, which depend on whether the day is wet or dry. To simulate the mean and standard deviation of the seasonal temperature, the third-order Fourier series is used. The residual values are calculated by subtracting the average values from the observed values, and the minimum and maximum data are used in time autocorrelation analysis. Minimum temperature, maximum temperature, precipitation and radiation form the outputs of this model. Calibrating, evaluating and creating meteorological data are three stages of LARS-WG model data generation. In the next step, using LARS-WG models under RCP 2.6, 4.5, and 8.5 scenarios and the micro-scale exponential LARS-WG generating model of Jiroft City climate changes during the planting period of each crop in the periods of 2011-2045, 2065-2046, 2066-2079 and 2080-2099. In the last stage, the effect of climate change scenarios on the planting pattern of Jiroft City was investigated by using the predicted climate change results and with the help of positive mathematical programming model. In this section, the current cultivation pattern of Jiroft city and the effects of changes in climate parameters predicted under different climate scenarios and patterns in the periods 2011-2045, 2046-2065, 2066-2079 and 2080-2099 are discussed. In the previous step, we will discuss the current cultivation pattern. In this regard, a positive mathematical programming model and GAMS25 software have been used. In the table, the area under cultivation, the production and performance of selected agricultural products and the consumption of inputs are shown separately for the agricultural year 2021-2022.



Results and Discussion

The results showed that the climatic parameters of temperature and precipitation have a significant effect on the performance of selected products. Also, by applying the forecast of climate variability in the cultivation pattern model of all selected crops in the periods 2011-2045, 2046-2065, 2066-2079 and 2080-2099 based on the noses of the HadCM3 model are affected by different climate scenarios. Considering the effects of climate change and improving the productivity of agricultural products, it is one of the bad effects of this phenomenon. The results of this research can be useful in the agricultural planning and economic development of Hamadan province.