With increased consumption of fossil fuels has come warnings that the global atmosphere could be overtaxed with carbon dioxide and other combustion byproducts. The most popular scenario suggests a warming of the subpolar area with an extension of the grain belt. This warming could place the present grain belt in a warmer and drier climate. Each time a portion of the grain belt experiences a temperature or precipitation anomaly, the suggestion of a climatic change is raised. The present paper addresses the question of medium-term, 95-year change in Iowa annual precipitation as well as linkage between precipitation and temperature anomalies. Similar studies in Europe and the United Kingdom, where unbroken precipitation records extend back almost 300 years, show periods up to 50 or 75 years where a jump in the annual mean has occurred. The fact that such anomalies extend back before the industrial revolution suggests other factors may cause such changes. With only about 100 years of climatological records here in the grain belt, it may not be possible to identify long-term, natural oscillations or a true, long-term trend. Records at four sites, Cedar Rapids, Des Moines, Dubuque, and Storm Lake, were analyzed in search of true jumps or trends in the climatic record. There was no question that the record had dry and wet periods, some extending over a period of ten or fifteen years. The conclusions were that, although extended periods seemed to be above or below the long-term mean, these anomalies had tenuous linkage between sites across the state. Possibly because of the sample size, no statistically significant trends were observed between sites through the years 1890-1984. Several poorly defined single site jumps were observed in the precipitation record, however, these were not clearly linked to companion temperature perturbations.
Proceedings of the Iowa Academy of Science
© Copyright 1987 by the Iowa Academy of Science, Inc.
Vaughan, Harry C.; Berning, Daniel J.; and White, Gary R.
"Variability of Annual Iowa Precipitation During the Past 95 Years,"
Proceedings of the Iowa Academy of Science: Vol. 94:
, Article 7.
Available at: http://scholarworks.uni.edu/pias/vol94/iss3/7