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Scott Hagen talks models and marshes

Scott Hagen - Hannah Hwang
Hagen discussed how his research intersects with his upbringing. Photo by Hannah Hwang.

Growing up on an Iowa farm, Scott Hagen knew a lot about the mechanics of agriculture. It was only after he stepped down from the tractor and into a research position at Louisiana State University, however, that he was able to see the other side of Iowan farming.

For the past 17 years, Hagen has been modeling issues related to global warming on the north coast of the Gulf of Mexico. He recently took an interest in the issue of hypoxia, or oxygen deficiency, in the region, otherwise known as the “dead zone,” off the coast of Louisiana. On Wednesday, Oct. 7, Hagen came to Grinnell to give a presentation about the relationship between the “dead zone” and agriculture in his home state.

Hagen began his talk by explaining some of his own research that he had been doing mapping the effects of rising sea levels on the southern shoreline. Looking at the varying predictions for sea level rise, Hagen spelled out for the audience what the abstract numbers might physically look like in the future. He emphasized that, rather than rising topographically like water in a bathtub would, rising sea levels will cause more extensive damage due to their interactions with tides and the resulting erosion.

“As we have higher sea levels, we erode away the coast,” Hagen said. “What it does is it leads to a landward encroachment … that landward encroachment makes our coastal infrastructure more vulnerable.”

More than just threatening infrastructure, this erosion can also target the natural marshes that grow along the delta. These marshes act as filters, to absorb much of the excess nitrogen that flows down the river.

This, he argues, is where climate change interacts with the nitrogen surplus produced by American farmland to exacerbate the problem of the large dead zone. There are, however, still enough marshes to help mitigate the effects of excess nitrogen if some fundamental reengineering of the Mississippi were to take place.

“One of the solutions that has been posed to deal with hypoxia on a very large scale, that will also benefit the loss of a coastline, is river diversions … to allow high flows of the Mississippi river and enough base flow, so we are sending the sentiment and nutrient laden waters out along the coast as they have been historically,” Hagen said.

Some efforts have been started to reduce hypoxia in the Gulf in recent years, although these have overwhelmingly proved ineffective. The goal that was laid out for 2015, to reduce the zone to 5,000 square kilometers, had to be re-evaluated and the benchmark pushed back to 2035. Part of the reason for these delays is the difficulty in reducing nitrogen usage on farms upstream. Growing up on a farm himself, Hagen understood the difficulties of this burden on farmers firsthand.

“Do I think that if we had green zones all along these streams and rivers, would that be beneficial? Hell yes, that’s the way it ought to be. But, you buy a farm, you try to make a living from it, and tell me what you’ve done 10 years from now,” Hagen said.

Despite these setbacks, Hagen was optimistic that real change could be accomplished in time. He pointed to the example of the Cuyahoga River in Ohio, which caught fire 13 times and is now a relatively clean waterway after large environmental initiatives were enacted. He argued that with time and concentrated effort, the enlarged hypoxia in the Gulf could go the way of the Cuyahoga and become a healthy, functioning marine ecosystem once again.


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