Forecasting Gulf’s hypoxia: The next 50 years?

This review discusses the use of hypoxia models in synthesizing the knowledge about the causes of Gulf of Mexico hypoxia, predicting the probable consequences of management actions, and building a consensus about the management of hypoxia. It also offers suggestions for future efforts related to simulating and forecasting Gulf hypoxia. The existing hypoxia models for the northern Gulf of Mexico range from simple regression models to complex three-dimensional simulation models, and they capture very different aspects of the physics, chemistry, and biology of this region. Several of these models were successfully calibrated to observations relevant for their process formulations and spatial-temporal scales. Available model results are compared to reach the consensus that large-scale hypoxia probably did not begin in the Gulf of Mexico until the mid 1970s, and that the 30% nitrogen load reduction that is called for by the Action Plan may not be sufficient to achieve its goal. The present models results suggest that a 40–45% reduction in riverine nitrogen load may be necessary to achieve the desired reduction in the areal extent of hypoxia. These model results underscore the importance of setting this goal as a running average because of significant interannual variability. Caution is raised for setting resource management goals without considering the long-term consequences of climate variability and change.