A one-dimensional time-dependent model is developed to characterize qualitatively and quantitatively the combined effects of bioturbation and burial on sedimentary signals related to abrupt climatic changes. This model is based on the widely used advection-diffusion equation and simulates rapid climatic transitions by representing the deposition flux at the sediment-water interface by a steep ramp function of time. This model is applied to both planktonic foraminifera abundance curves and δ18O distributions. Output signals, obtained at the bottom of the bioturbated layer for these rapid transitions, have been generated for a broad range of sedimentation rates (5--50 cm kyr-1), biodiffusion coefficients (10-3 -1 cm2 yr-1), and mixed layer thicknesses (2--15 cm). Numerical results clearly demonstrate the importance of a dynamic description of sediment mixed layers. Properties of the sedimentary response to fast transitions appear to be highly and nonlinearly dependent upon the sedimentation rate and the relative values of the original transition length and the time required to bury the signal below the mixed layer. Moreover, for low sedimentation rates (≤10 cm kyr-1) we show that signals occurring over a 50- to a 250-year timescale are indistinguishable. To quantify the distortion of sedimentary signals, we determined the transition length of the bioturbated simulated signals and compare it to the initial transition length for given sets of bioturbation and sedimentation rates and mixed layer thicknesses. Comparison between model predictions and experimental results reveals a good agreement, showing that transition timescales are compatible with ice core-derived transitions (<100 years) for environments in which bioturbation can be approximated by a diffusive process. Tests performed on δ18O distributions have illustrated the effect of bioturbation on the stratigraphic offsets between isotopic compositions of cold and warm species of foraminifera during climatic transitions.