UNCERTAINTY OF CLIMATE CHANGE IMPACTS ON SOIL EROSION FROM CROPLAND IN CENTRAL OKLAHOMA

Impacts of climate change on soil erosion and the potential need for additional conservation actions are typically estimated by applying a hydrologic and soil erosion model under present and potential future climate conditions. Projecting future climate conditions harbors several sources of uncertainty that, in turn, lead to uncertainty in projected soil erosion rates. Awareness of these uncertainties is essential to the development of flexible and affordable conservation and adaptation measures that remain effective over the broad range of climate projections. In this study, three climate-associated sources of uncertainties were selected to examine their effect on projected soil erosion for winter-wheat cropland in central Oklahoma. Forty soil erosion distributions representing various combinations of two emission scenarios, ten climate projection models (incl. downscaling), and two storm intensification alternatives were developed and evaluated. The total uncertainty range of 40 projected soil erosion distributions was 2.1 to 18.2 Mg ha(-1) yr(-1) at the median, and 25.0 to 114.0 Mg ha(-1) yr(-1) at the 10% Probability of Exceedance level. For the selected climate change scenarios, climate models, and Oklahoma climate conditions, the uncertainty due to imperfect prediction tools (climate models, downscaling methods) and model choices (storm intensification) was found to be sizably larger than the inherent uncertainty associated with the realization of a future climate outcome (emission scenario). It was concluded that uncertainties in projected soil erosion rates can potentially be large and should be given full consideration in planning future conservation needs.