A. It has been estimated that the world's water use could triple in the next two decades.
B. Plant and animal species are becoming extinct at a greater rate now than at any time in earth's history.
C. The overuse of antibiotics (抗生素) both in humans and in farm animals has contributed to the growth of antibiotic resistant micro-organisms (微生物).
D. Yet, there is reason to have hope for the future.
E. Until recently, very little information was documented about changes and consequences of land usage.
F. Such changes cause changes in local and regional climate, and will determine the future of agriculture.