This year’s survey of the dead zone in the Gulf of Mexico was just completed. And although it didn’t shatter record size as previously thought, the findings still show the problem worsening.
The dead zone is caused by a phenomenon known has hypoxia. When nutrients from farming fertilizers run into rivers and pour into the ocean, massive amounts of phytoplankton grow. As the excess phytoplankton get consumed by bacteria, the decomposition process depletes oxygen and creates an uninhabitable area. According to a 2008 study, there are 400 dead zones around the world making up an area about half the size of California.
At 6,765 square miles, this year’s dead zone in the Gulf of Mexico was above average. Researchers were expecting to find a record-breaking zone of between 8,500 and 9,400 square miles due to high water levels on the Mississippi River, but a tropical storm whipped up dissolved oxygen around the zone and decreased the area. According to an interview with one of the researchers in the New York Times, the problem is still getting worse:
“It would have been the largest if we had been out there at the right time, I suppose,” Rabalais said in a phone interview this morning.
The dead zone will likely re-form as the waters calm, said Rabalais. The scientists will set out again for their regularly scheduled two-day follow-up cruises in August and September to take additional measurements before the zone recedes in the fall, although the official size verdict likely will not change.
Along with above-average size of the existing dead zone, researchers found a new zone east of the Mississippi that is almost as big.
A changing climate will only exacerbate the problem. In May, the Army Corps of Engineers had to blow up a levee and flood 130,000 acres of farmland due to a record-smashing flood. With 100 and 500-year floods coming with ever-increasing frequency, erosion and fertilizer run-off will continue to get worse, expanding the dead zone to new areas. As this year’s survey shows, that expansion is underway.