Ethanol Production and the Gulf of Mexico Dead Zone

The issue of the Gulf of Mexico Dead Zone always comes up at this time of year. It is around this time every year that the predictions for the size of the dead zone come out. And over the last few years it is also around this time that talk of the relationship between ethanol production and the size of the dead zone ramps up.

This year is no exception. I have seen several articles in the news suggesting that the size of the dead zone is growing because of ethanol production. I have looked at the numbers before and honestly it is hard to make a case that the dead zone is growing and even harder to make the case that ethanol is having an effect. First let's look at the size of the dead zone over the last few years.

2009 - 3000 square miles
2008 - 7988 square miles
2007 - 7903 square miles
2006 - 6662 square miles
2005 - 4564 square miles
2004 - 5800 square miles
2003 - 3220 square miles
2002 - 8484 square miles
2001 - 8006 square miles

Looking at the numbers it is easy to see that they bounce around quite a bit from year to year. And even though the 2007 and 2008 numbers are quite large they aren't as large as the 2001 and 2002 numbers. So it is hard to make a case that over the last few years that the size of the dead zone is getting larger.

Now let's look at the same numbers with the totals for ethanol production added.

2009 - 3000 square miles - 10,758,258,000 gallons
2008 - 7988 square miles - 9,000,000,000 gallons
2007 - 7903 square miles - 6,500,000,000 gallons
2006 - 6662 square miles - 4,855,000,000 gallons
2005 - 4564 square miles - 3,904,000,000 gallons
2004 - 5800 square miles - 3,400,000,000 gallons
2003 - 3220 square miles - 2,800,000,000 gallons
2002 - 8484 square miles - 2,130,000,000 gallons
2001 - 8006 square miles - 1,770,000,000 gallons

As you can see ethanol production was five times greater last year than it was in 2002 when the record was set. It is hard to see any direct correlation between ethanol production and the size of the dead zone.

This year NOAA is predicting the dead zone will be larger than average.

Scientists are predicting the area could measure between 6,500 and 7,800 square miles, or an area roughly the size of the state of New Jersey. The average of the past five years is approximately 6,000 square miles.

And just how did they come up with that number?

This forecast is based on Mississippi River nutrient flows compiled annually by the U.S. Geological Survey. Dead zones off the coast of Louisiana and Texas are caused by nutrient runoff, principally from agricultural activity, which stimulates an overgrowth of algae that sinks, decomposes, and consumes most of the life-giving oxygen supply in the water.

And yet they say that nutrient runoff is less this year than in years past.

“The 2010 spring nutrient load transported to the northern Gulf of Mexico is about 11 percent less than the average over the last 30 years,” said Matthew Larsen, Ph.D., USGS associate director for water.

It is hard to understand how they came up with a higher than average prediction based on lower than average nutrient runoff.

It is worth noting that last year they predicted the dead zone would measure between 7,450 and 8,456 square miles. The actual size turned out to be less than half that at 3,000 square miles.

In 2008 they predicted the dead zone would measure 8,800 square miles and the actual size turned out to be right at 8,000 square miles. So they are usually closer than they were last year. But I have been watching this for several years now and the prediction is always higher than the actual total turns out to be. The problem with that is that the prediction always gets more attention focused on it than the actual total does. So the public is left with the impression that the dead zone just keeps growing and growing.