Previous simulations of martian global dust storms with a simple low-order model showed the desired interannual variability of storms if one of the model parameters-the threshold wind speed for starting saltation and lifting dust from the surface-was finely tuned. In this paper we show that the fine-tuning of this parameter could be the result of negative feedback in which processes associated with global dust storms raise the threshold and small-scale processes like dust devils, which are active in years between the storms, lower the threshold.