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theses

Anthropogenic climate changes could affect agricultural productivity due to changes in temperature, precipitation, solar radiation and CO2 concentration. To be well prepared for possible futures, it is necessary to study yield changes of major crops under different climate scenarios. Here I consider two situations: solar radiation management geoengineering and a regional nuclear war. Although I certainly do not advocate either scenario, we cannot exclude the possibilities: if global warming is getting worse, the world might consider deliberately manipulating global temperature; if nuclear weapons still exist, we might face a nuclear war catastrophe. I used the Decision Support System for Agrotechnology Transfer (DSSAT) crop model to simulate crop yield changes in China under different climate scenarios. Before agriculture simulations, I first evaluated DSSAT for rice, maize and wheat yields in China. Both G3S geoengineering (reducing solar radiation to balance radiative forcing of Representative Concentration Pathway 4.5 (RCP4.5)) and G2 geoengineering hve no significant impact on Chinese rice production and combined with the CO2 fertilization effect, the cooling effect due to geoengineering would improve Chinese maize production by 10% and 14%, respectively. The different responses to G3S and G2 are due to the stronger cooling effect of G2 compared with their reference cases, RCP4.5 and 1pctCO2, respectively. The termination of G2 geoengineering shows negligible impacts on rice production but a 20 Mt (12%) reduction of maize production. The CO2 fertilization effect compensates for the deleterious impacts of climate changes due to G2 geoengineering on rice production, increasing rice production by 8.6 Mt and enhances maize production in G2, contributing 8 Mt (42%) to the total increase. A regional nuclear war would reduce annual rice production by 23 Mt (24%), maize production by 41 Mt (23%), and wheat production by 23 Mt (50%). This reduction of food availability would continue, with gradually decreasing amplitude, for more than a decade. Assuming these impacts are indicative of those in other major grain producers, a nuclear war using much less than 1% of the current global arsenal could produce a global food crisis and put a billion people at risk of famine.

ETD_5407

Ph.D.

Includes bibliographical references

by Lili Xia

doi:10.7282/T3VH5M45

ETD doctoral

The author owns the copyright to this work.