ABSTRACT
Trade is dependent on co-existent surpluses and deficiencies. The century-old Canadian wheat trade is based on the surplus production of the Prairies and the global market environment. The trade has enabled Canada to prosper, and changes therein have affected Canada dramatically. The variability in supply and demand is highly dependent on climate. Periods of favourable weather and drought have been associated with prosperity and disaster to the western plains. Society may react in distinctive ways, for example through migration. Nevertheless, it will be useful to review the possible significance of long-term climatic shifts when confronted by adverse climatic trends. There are many examples, of course, where people remain in areas near the limits of climatic thresholds of crop production. A more variable climate is the more probable source of the more urgent agricultural risks. The yield per hectare of Canadian wheat has been highly variable throughout history.
