Dead Sea scrolls: In the red part, "habitats that would normally be teeming with life become, essentially, biological deserts," NOAA says. NOAA.
First, the good news: The annual "
dead zone"
that smothers much of the northern Gulf of Mexico—caused by an
oxygen-sucking algae bloom mostly fed by Midwestern farm runoff—is
smaller this year than scientists had expected. In the wake of heavy
spring rains, researchers at the National Oceanic and Atmospheric
Administration had been projecting 2013's fish-free region of the Gulf
to be at least 7,286 square miles and as large as 8,561 square
miles—somewhere between the size of
New Jersey on the low end to
New Hampshire on the high end. Instead, NOAA
announced, it has clocked in at 5,840 square miles—a bit bigger than
Connecticut. It's depicted in the above graphic.
Now, for the bad news: This year's "biological desert" (NOAA's
phrase)
is much bigger than last year's, below, which was relatively tiny
because Midwestern droughts limited the amount of runoff that made it
into the Gulf. At about
2,900 square miles, the 2012 edition measured up to be about a third as large as
Delaware.
NOAA. Data source: Louisiana Universities Marine Consortium (LUMCON)
Smaller than expected though it may be, this year's model is still
more than twice as large as NOAA's targeted limit of less than 2,000
square miles. Here's how recent dead zones stack up—note that the NOAA
target has been met only once since 1990. Low years, like 2012 and 2009,
tend to marked by high levels of drought, and high years, like 2008, by
heavy rains and flooding.
Dead zones over time NOAA
Why such massive annual dead zones? It's a matter of geography and
concentration and intensification of fertilizer-dependent agriculture.
Note that an enormous swath of the US landmass—41 percent of it—drains
into the Mississippi River basin, as shown below. It's true that even
under natural conditions, a river that captures as much drainage as the
Mississippi is going to deliver some level of nutrients to the sea,
which in turn will generate at least some algae. But when US Geological
Survey researchers
looked at the fossil record in 2006,
they found that major hypoxia events (the technical name for dead
zones) were relatively rare until around 1950—and have been increasingly
common ever since. The mid-20th century is also when farmers turned to
large-scale use of synthetic fertilizers. Now as much a part of
Mississippi Delta life as crawfish boils, the Gulf dead zone wasn't even
documented as a phenomenon until 1972, according to
NOAA.
Source: LUMCON
The very same land mass that drains into the Gulf is also the site of
an enormous amount of agriculture. The vast majority of US corn
production—which uses titanic amounts of nitrogen and phosphorus, the
two main nutrients behind the dead zone—occurs there.
US Department of Agriculture
The region is also where we shunt much of our factory-scale meat farms. This
Food and Water Watch map depicts concentration of beef cow, dairy, hog, chicken, and egg farms—the redder, the more concentrated.
Big Ag interests like t
o deflect blame for the annual dead zone,
claiming that other factors, like runoff from lawns and municipal
sewage, drive it. But the US Geological Service has traced flows of
nitrogen and phosphorus into the Gulf, and there's no denying the link
to farming. "In total, agricultural sources contribute more than 70
percent of the nitrogen and phosphorus delivered to the Gulf, versus
only 9 to 12% from urban sources," the USGS
reports.
The Gulf of Mexico isn't the only water body that bears the brunt of
our concentrated ag production. Much of the eastern edge of the Midwest
drains into the Great Lakes, not the Gulf. And they, too, are
experiencing fertilizer-fed algae blooms—particularly
Lake Erie.
The below satellite image depicts the record-setting, oxygen-depleting
bloom that smothered much of Lake Erie in 2011, which peaked at 2,000
square miles (about Delaware-size). "That's more than three times larger
than any previously observed Lake Erie algae bloom, including blooms
that occurred in the 1960s and 1970s, when the lake was famously
declared dead," a University of Michigan
report
found. The culprit: severe storms in the spring, plus "agricultural
practices that provide the key nutrients that fuel large-scale blooms."
University of Michigan
Then there's the Chesapeake Bay region, site of a stunning concentration of factory-scale chicken facilities (
Food and Water Watch map)…
Food and Water Watch
…and a massive annual dead zone. "Livestock manure and poultry litter
account for about half of the nutrients entering the Chesapeake Bay,"
the Chesapeake Bay Program
reports:
Source: NOAA
All of which raises the question: Are dead zones inevitable, a
sacrifice necessary to feeding a nation of 300 million people? Turns
out, not so much. A 2012 Iowa State University
study
found that by simply adding one or two crops to the Midwest's typical
corn-soy crop rotation, farmers would reduce their synthetic nitrogen
fertilizer needs by 80 percent, while staying just as productive. And
instead of leaving fields bare over winter, they could plant them with
cover crops—a practice that, according to the
US Department of Agriculture,
"greatly reduces soil erosion and runoff" (among many other ecological
benefits)—meaning cleaner streams, rivers, and ultimately, lakes, bays,
and gulfs. Moreover, when animals are rotated briskly through
pastures—and not crammed into
factorylike structures where their manure accumulates into a dramatic waste problem—they, too, can
contribute to healthy soil that traps nutrients, protecting waterways from runoff.
The
IDF launched an airstrike on Gaza early Wednesday morning in response
to rockets fired into southern Israel from the territory, the army said
in a statement.
