The Missouri River Basin (MRB) is the largest river basin in the U. S. A., and is one of the most important crop and livestock-producing regions in the world. A study of statistical associations between decadal climate variability (DCV) phenomena and hydro-meteorological (HM) variability in the MRB found that positive and negative phases of the Pacific Decadal Oscillation (PDO), the tropical Atlantic sea-surface temperature gradient variability (TAG), and the west Pacific Warm Pool temperature variability (WPWP) were significantly associated with decadal variability in precipitation and surface air temperature in the MRB, with combinations of various phases of these DCV phenomena associated with drought, flood, or neutral HM conditions.

We have developed a methodology, based on hydrology and land use models, to assess whether the aforementioned DCVs directly affect the hydrology and crop yields in the MRB. The results of our research show that realistic valuses of indices of the three DCV phenomena can change water yields by as much as ±20% of average water yield in some locations; and dryland corn and spring and winter wheat by as much as 40-50% of average yield in some locations in the MRB. These impacts are also evident in MRB-aggregated water and crop yields. The combined and cumulative effects of these DCV phenomena on the MRB HM, water availability, and crop yields can be dramatic with important consequences for the MRB.

In view of these quantified impacts of decadal droughts (and wet epochs) on water and crop yields in the MRB, we have conducted a series of related activities to assess decadal climate information (DCI) needs for decision support in water and food production sectors in the MRB. This assessment was carried out via workshops and individual meetings involving 120 representative stakeholders. In this oral presentation, the aforementioned decadal drought impacts on water and crop yields, major conclusions about users' awareness of decadal dry and wet epochs, and their societal impacts in the MRB that are substantially and qualitatively different from impacts of seasonal to interannual climate variability; their DCI needs; potential barriers to using decadal climate predictions/outlooks; lessons for climate scientists; and recommendations from users will be described.