The Effect of Climate Change on Iran's Agricultural Production: A Case Study of Wheat Crop

Introduction
Climate change, with less access to water, results in product yields, and as a result of declining production, the economic consequences are affected by these changes, and the farmer experiences a reduction in income resulting from a decline in his performance (Gohar & Kashman, 2016) .
Iran's presence in the dry and semi-arid belt of the world has always been caused by dehydration and alternate droughts. Climate change, with a decline in access to water, yields products, and as a result of declining production, the economic consequences are affected by these changes and the farmer experiences a decline in income resulting from a decline in his performance.
Wheat is one of the products affected by these changes. In Iran, this product is considered to be the most important and most cultivated crop. In the 2012-2015 crop year, the level of wheat cultivation in Iran was 5928728 hectares and its production was 14592003 tons. It is a statistic that indicates both the level of cropping and the production of this product in a high level and volume. This product is 50.39% of the total cultivation and 17.58% of total crop production in the mentioned crop year (Agricultural Statistics, 2017).

Materials and Methods
Using a positive mathematical programming as well as information on the wheat crop during the years 1339-1394, the trend of cultivars, incomes and prices of wheat climatic assumptions over 20 years is discussed. This goal was pursued using GAMS software in the present study. CROPWAT software was used to calculate the need for water in the cost and product sector. The method of pmp was first introduced by Hawait. As the most commonly used method for calibration, a mathematical programming model is performed in three steps. In the first step, the linear programming model is determined by considering the calibration limitations, and in the second stage, with the help of the dual values of the previous stage model, a nonlinear objective function is formed. In the third step, the calibrated target function is used as a nonlinear programming model for policy analysis (Moghadasi & Bakhshi, 2014).
Climate scenarios in this study will be achieved with regard to climate variability and change in average annual rainfall. Research scenarios include: normal climate change, climate change, climate Variability, and Double Exposure.

Results & Discussion
Climate change can be mentioned as an unavoidable phenomenon around the world, which is unlikely to be much more severe in Iran due to its particular geography and dry and semi-arid climate. In the meantime, the agricultural sector has been and will be more vulnerable to these natural changes due to the strong dependence on natural phenomena. Following the variability of this part of the climate change, agricultural production is affected first and foremost. In fact, climate change will change the price of products and income of farmers by changing production levels. In this study, the effects of climate change on agricultural production have been evaluated to study the effect of four different climate scenarios on rainfall, cropping area, yield and price of wheat products as one of the most important agricultural products in Iran. The results show that among the four scenarios studied, climate change and climate change scenarios have more severely affected the studied cases. The first issue is the effect of different scenarios on rainfall, which results in a significant reduction in precipitation over a period of 20 years. This would be to a degree where the average rainfall in both the climate change and climate change will decrease by an average of 50% annually, as compared to two other situations. Under these two scenarios (climate change and climate change), cropping levels and income levels will fall further than the other two scenarios. In these two scenarios, wheat prices will be higher than other scenarios. Based on the results of this study, the continuation of climate change and the lack of appropriate policies to confront and adapt to these changes will be unavoidable. Reducing income and rising prices will lead to a reduction in the welfare of producers and consumers.
Key words: Climate change, Climate variability, Wheat production, Iran.