How Industrial Agriculture Makes us Vulnerable to Climate Change, Mississippi Floods Edition

Nancy Rabalais, marine scientist and executive director of the Louisiana Universities Marine Consortium, is probably our foremost authority on the vast, oxygen-depleted "dead zone" that rears up annually in the Gulf of Mexico, fed by fertilizer...

May 23, 2011 | Source: Grist | by Tom Philpott

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Nancy Rabalais, marine scientist and executive director of the Louisiana Universities Marine Consortium, is probably our foremost authority on the vast, oxygen-depleted “dead zone” that rears up annually in the Gulf of Mexico, fed by fertilizer runoff from large Corn Belt farms. (I interviewed her for my podcast last year.)

In a report on the PBS Newshour blog, Rabelais delivers some bad news: Floods in the Mississippi River watershed this spring are washing tremendous amounts of fertilizer into Gulf, promising to generate the largest dead zone on record.

In addition to carrying in fertilizer runoff, the floods threaten to worsen the dead-zone problem by flushing in much more fresh water than normally makes it into the Gulf, PBS reports:

 A surge of fresh water creates a layering effect in the seawater, which compounds the problem. The freshwater sits above the heavier saltwater, acting as a cap that prevents oxygen from reaching the deeper water levels.

Agribusiness interest groups like to sow doubt about the cause of the annual dead zone by claiming that other factors, such as residential lawns, contribute more fertilizer runoff than agriculture. I obliterated that notion in this post last year.

The fact that heavy rains in the Midwest translate to the ruin of larger swaths of the Gulf fishery points to an uncomfortable truth about industrial agriculture: It makes us more vulnerable, not less, to the very weather shocks (e.g., severe flooding) that we can expect from unchecked climate change.