Many agriculturalists are concerned that climate change may increase pest migration and population increases, which could have very detrimental effects on the productivity and profitability of agriculture. The authors assess how current climate variations affect pesticide costs per acre in the U.S. as an indicator of the impacts of pest population changes. Examining pesticide costs independently for corn, cotton, potatoes, soybeans, and wheat, they found that all the studied crops required increased pesticide expenditures when rainfall increased, and all but wheat had higher costs with higher temperatures. Increased rainfall also increased the cost variability for cotton, while decreasing variability for the other crops. Higher temperatures corresponded to increased cost variability for corn, potatoes, and wheat and decreased variance for soybeans.