Record Mississippi River flooding could cause Gulf of Mexico’s largest “dead zone”

Just off the coast of Louisiana, Texas, Mississippi, and Alabama, a large dead zone is anticipated to grow in the next few weeks, largely due to record amounts of water flowing down the Mississippi River. A dead zone is an area of water that is void of oxygen needed to support plant and animal life.

The dead zone phenomenon happens every year but scientists with the National Oceanic and Atmospheric Administration believe this year could be one of the largest ever, due to abnormally high levels of water being discharged from the Mississippi River system.

The Mississippi River is the longest river in the United States and the second-largest drainage system on our continent (behind Hudson Bay). As water flows out of farm fields and cities, it enters the tributaries of the Mississippi River. Locally, this includes the Cedar, Rock, Maquoketa, Wapsipinicon, and Iowa Rivers. River flood warnings are in effect from the Quad Cities, all the way to New Orleans right now.The water in the Mississippi has high levels of nutrients and sewage (which acts as a fertilizer) that flows directly into the Gulf of Mexico. There, the fresh water (which is less dense than ocean water), sits on top of the salty water. As water temperatures warm into the upper 80s and lower 90s, algae blooms and can be significant. The northern Gulf of Mexico is interesting because it doesn't have an overwhelming amount of current.

The "Loop Current" is the body of water's strongest, which takes water out of the Caribbean, sending it from west to east through the Florida Straits.

The blooming algae that is stuck along the Gulf Coast eventually dies and the decomposition process takes most of the oxygen out of the water.

This lack of oxygen kills most sea life including plants and fish, having a direct effect on the people along the Gulf Coast that depend on fishing and shrimping for a living.

Those are the human and nature impacts. But you'd be surprised at how much humans are causing this. It's not just agriculture and urbanization, human-caused climate change has a significant effect on how often this occurs.

Extreme rain and snow are direct effects of human-caused climate change. Near-record amounts of snow fell across much of the Midwest this season, due to an imbalance in the jet stream, caused by human-caused climate change.

We are seeing significant flooding of the Mississippi River every 5 years or so these days. If you're having trouble wrapping your head around the significance, think about this: we're having a "hundred-year flood" every few years. That's not a natural occurrence.

-Meteorologist Eric Sorensen



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