What is already known:
What this study adds:
A 16 GCM ensemble was used to assess the future climate of Oklahoma and its Blue River Basin under three IPCC emissions scenarios. Output from the models was then applied to a monthly water balance model to predict changes in the hydrologic cycle. By the end of the century ensemble median warming is predicted to be 2.2 to 4.6 °C for the state depending on the scenario. Precipitation trends depended on the emissions scenario, with the state experiencing almost no annual change. The Blue River Basin is expected to receive slightly more precipitation under the lower emissions scenario and less under the higher scenario. Change in temperature along with little change in precipitation led to predicted increase in both potential evapotranspiration and actual evapotranspiration. Soil moisture and runoff are both expected to decrease significantly. Runoff changes by 2100 ranged from ensemble mean of -9.6% for the lower emission scenario to -29.8% for the higher.