U.S. Environmental Protection Agency
EPA Science Advisory Board
Background Information

Document NameFuture perspectives for hypoxia in the northern Gulf of Mexico
Document AuthorJustić, D.
Rabalais, N.N.
Turner, R.E.
Short DescriptionPp 435-449 in N. N. Rabalais and R. E. Turner (eds.), Coastal Hypoxia: Consequences for Living Resources and Ecosystems. Coastal and Estuarine Studies 58, American Geophysical Union, Washington, D.C.
CategorySubgroup 1: Characterization of the Cause(s) of Hypoxia
Publication Year2001

Abstract: General circulation models predict that Mississippi River runoff would increase 20% if the concentration of atmospheric CO2 doubles. This hydrologic change would be accompanied by an increase in winter and summer temperatures over the Gulf of Mexico coastal region of a 4.2oC and 2.2oC, respectively. Using a coupled physical-biological model, we examined the potential effects of climate variability on the Gulf of Mexico hypoxic zone. Model simulations suggest that increased freshwater inflow and surface oxygen cycling in the coastal waters of the northern Gulf of Mexico. In simulation experiments, a 20% increase in annual runoff of the Mississippi River, relative to a 1985-1992 average, resulted in a 50% increase in net primary productivity of the upper water column (0-10 m) and a 30 to 60% decrease in summertime subpycnoclincal oxygen content within the present day hypoxix zone. These model projections are in agreement with the observed increase in severity and areal extent of hypoxia during the Great Mississippi River Flood of 1993.