The Effects Of Climate On Agricultural Product Price ——A Case Study Of Corn Price

Food is the necessities of people's life and the basis to maintain social stability.Maintaining stable food supply and stable food prices is the primary condition for ensuring and improving people's livelihood.In recent years,with the increasing frequency of extreme weather events,its impacts on the food supply stability has become stronger and stronger.It is thus imminent to develop a climate-informed food security early warning system.This thesis takes the corn price in the United States,the world's largest corn trading market,as an example to analyze the price fluctuation between 1981 and 2019.Ten periods in the corn growth season are analyzed,which are May to June,May to July,May to August,May to September,June to July,June to August,June to September,July to August,July to September and August to September.The relationship between corn price fluctuations and temperature,rainfall and vapor pressure deficit through different periods is explored.Corn price prediction models are established based on the most suitable combinations of climate indicators.The fitting and prediction performance of the models are investigated to evaluate the explanatory ability and prediction skill of the climate-informed models of different periods.The research conclusions of the thesis are as follows:(1)There is no obvious trend and autocorrelation of corn price between months.The sharp fluctuations of corn prices are related to extreme weather,for the price fluctuations in different periods reach the highest at the years of extreme high temperature and extreme rainfall.In terms of the relationship between price and temperature,extreme high temperature will push up the corn prices,while extreme low temperatures will lower the corn prices.Regarding the relationship between price and rainfall,both lack of rainfall and excessive rainfall can elevate corn prices.(2)Based on the growth characteristics of corn,17 climate indicators are defined to represent the climatic conditions,including heat stress,cold stress,atmospheric dryness,soil dryness and water stress.The impacts of heat stress and atmospheric dryness on corn price fluctuation are mainly observed in July and August,while the effects of cold stress and soil dryness on corn price fluctuation are mainly detected in May and June.Among all climate stress indices,heat stress has the most significant impact on the corn price fluctuation.(3)According to the established models,the price fluctuation variance explained by climate indices in different periods is between 16% and 75%,and the accuracy of the models in predicting the direction of price ups and downs is between 59% and 85%.The prediction performance is related to climate condition.Under the condition of extreme high temperature and extreme dry condition,the model's ability to accurately predict the magnitude of price fluctuation will decrease,while it will still maintain a high accuracy rate in predicting the direction of price fluctuations.