A Dead Zone the Size of New Jersey Is Growing in the Gulf of Mexico

Every year, a massive "dead zone" blooms in the Gulf of Mexico. Inside its amorphous boundaries almost all life is extinguished. There's simply not enough oxygen for marine creatures to survive.

The phenomenon is caused by what the National Oceanic and Atmospheric Administration calls "excessive nutrient pollution"—a surplus of nitrate-heavy fertilizer runoff produced by agricultural operations along the Mississippi River. That runoff bleeds out from farms and ranches across the south into the nation's mightiest—and dirtiest—river, and eventually winds its way into the Gulf.

All those nutrients cause massive algae feeding-frenzies that suck up all of the available oxygen, creating what scientists call "hypoxic" (very low oxygen) and "anoxic" (no oxygen) zones. Dead zones. They occur in oceans all over the place, but the one that consumes vast swaths of the Gulf of Mexico is especially huge. Here's how huge: this year, NOAA expects that dead zone will be between 7,286 and 8,561 miles wide.

Or, in the NOAA report's words, "That would range from an area the size of Connecticut, Rhode Island and the District of Columbia combined on the low end to the New Jersey on the upper end." That puts this year's aquatic death radius in the running to be the biggest ever—the largest Gulf dead zone on record thus far was the 8,481 square mile behemoth that grew in 2002.

"It's the largest in the Atlantic. The second largest in the world," R. Eugene Turner tells me in an interview. Turner is an oceanographer at LSU; he created one of the models behind NOAA's startling projections.

"We know it's manmade. We know it wasn't there in the 50s and 60s," Turner says. "And one third of U.S. fisheries are harvested in that region—or were."

So why is the dead zone so big this year? Mostly because of all the flooding in the Midwest. The unusually stormy spring and early summer seasons have led to larger-than-usual nitrate-rich runoff to flood the Mississippi. By way of comparison, last year, a time of epic drought, saw the fourth smallest dead zone on record.

And that means dead zones like this one are likely to continue expanding. As climate change continues, the warmer air will hold more moisture—scientists expect to see more extreme weather events like flooding in already wet regions as carbon continues to concentrate in our skies.

"Climate variability and climate change are part of the reason we have variability in the prediction every year," Turner says. "And it's part of the reason it's getting bigger ever year." Climate affects the discharge of the river, he says. The more runoff upstream, the larger the dead zone. He also notes that it warms the waters, which ripens conditions for the deadly algal blooms.

Meanwhile, that excessive carbon is also getting absorbed by oceans—which crowds out oxygen and further expands dead zones. A 2009 study from the Monteray Bay Research Institute foungt that "low-oxygen 'dead zones' in the ocean could expand significantly over the next century. These predictions are based on the fact that, as more and more carbon dioxide dissolves from the atmosphere into the ocean, marine animals will need more oxygen to survive."

Furthermore, these dead zones also cause more climate change, too. A 2010 study from scientists at the University of Maryland found that hypoxic zones produced more of the greenhouse gas nitrous oxide—thus perhaps making the dead zones a dangerous feedback loop to take into account.

Clearly, aquatic life in the Gulf of Mexico—fish to plankton to very endangered sea turtles—can't catch a break. On top of record-breaking oil spills and regular industrial pollution, it's now got a dead zone that will regularly kill everything within an area about the size of New Jersey.

"It's really pretty amazing we're having this kind of effect," Turner says. "It's not exactly taking care of mother Earth."