2024-03-29T05:47:46Z
https://repository.dl.itc.u-tokyo.ac.jp/oai
oai:repository.dl.itc.u-tokyo.ac.jp:00005452
2022-12-19T03:47:03Z
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気候変動による中国とアメリカのトウモロコシ生産への影響とリスク緩和戦略の研究
Impacts of Climate Change on Maize Production in China and the U.S. and Possible Risk Mitigation Strategies
Li, Xiang
11380
climate change, maize production, interrelationship, climate and socioeconomic inputs, risk, mitigation
University of Tokyo (東京大学)
博士(農学)
It has become increasingly clear among scientists that a continuous increase in atmospheric greenhouse emission is changing the climate of earth. Among various climate change sensitive ecosystem, agriculture is a key sector to support the sustainable economic development of our society in this century. Given the backdrop of the fact that the share of maize production in China and the U.S. is over 50% of total maize production amount in the world, this thesis analyzed the interrelationship between climate change and maize production in China and the U.S. with a multidisciplinary approach, predicted the potential effects of climate change on maize production, and proposed alternative risk mitigation strategies to reduce the whole-country risk of maize reduction. This thesis did three case studies in China and the U.S., where climate inputs, socioeconomic inputs, and technology improvement (with and without) were taken into the consideration. While the first study analyzed the maize production in the Midwestern United States and Middle China with a semi-optimized supply function, the following two studies separately analyzed maize production responses in the North and the South of two countries with a regression function (Cobb-Douglas production function) and converted supply functions. The major finding of the first case study is that climate change will not universally cause negative impacts of maize yields in the United States and China. The results of a simulation of climate change on maize yields over the period 2008–2030 showed that variation in regional climatic and economic conditions could make the impacts of climatic change on maize yields substantially different in different regions. Even with significant changes in climate conditions that alter the maize crop‟s growing environment and affect crop yields, a decrease in maize supply due to a decrease in maize yields would lead to an increase in the maize price, which in turn would induce farmers to add more investments in production inputs to raise yields. Thus, the decrease in actual yields may not be as dramatic as predicted in cases where only climate factor are considered. The second study indicates that the impacts on maize production will likely be the opposite in the Northeast and the Southwest of China. The results indicate that a higher flexibility of production timing in the Southwest region allows farmers to better adapt to climate change than the Northeast region. Moreover, the gains in the Southeast may outweigh the potential reduction of maize production in the Northeast region. When a further reduction of agricultural labor population occurs, maize production decreases more in the Southwest region, even the substitution of more machinery for human labor is allowed. This result reflects that terraced, sloped lands in the Southwest region limit the effective use of machinery. The third case study indicates that under the same climate change South region tends to respond oppositely relative to the North Central region in the U.S., implying that one region‟s losses could be partially offset by the other region‟s gains. The different responses imply that the South region could provide potential risk mitigation to climate change within the United States and could help the nation maintain its maize production balance. All simulated results indicated that maize production could respond oppositely among different countries and regions through 2030. It has been noticed that advanced international and inter-regional contracts and cooperation as well as policies could mitigate the entire-country risk of reduced production and to stabilize regional agricultural labor force. Moreover, the gains in the Southeast may outweigh the potential reduction of maize production in the North region in China and the U.S. The risk mitigation strategies provided in this thesis are expected to impact the stability of food production self-sufficiency in China and the U.S. and the price stability of the international commodity market, as well as to be applied to other countries like Japan.
thesis
2013-03-25
2013-03-25
application/pdf
https://repository.dl.itc.u-tokyo.ac.jp/record/5452/files/H24_3943_Li.pdf
eng