Q. For years, we’ve heard that Louisiana loses a football field of coastal land every hour. We’ve even seen some references to every 45 minutes and every 30 minutes. Is it possible that much land has disappeared over the years and there’s still any coast left?
A. We went to The Advocate’s environmental reporter, Amy Wold, for help on this one. She tells us the short answer is yes on both counts.
Doing the math, the loss of a football field an hour is 8,760 football fields a year.
A football field is 1.3 acres. Multiply that by 8,760 and you get 11,388 acres a year lost.
Since there are 640 acres in a square mile, that comes up to a loss rate of about 17.7 square miles a year.
That’s pretty darn close to the United States Geological Survey’s report of 16.5 square miles of loss every year from 1985 to 2010.
It’s important to remember that’s the average just for those years. Land loss is highly variable over time. During some periods, there may be little land loss and then a tropical storm could erase the equivalent of thousands of footballs fields in just an hour, says Brady Couvillion, research geographer with USGS.
“This comparison to something people can visualize has helped tremendously with people understanding the scope of the problem,” Couvillion wrote in an email response. “When we say ‘16.6 square miles per year,’ that is hard for anyone to visualize. Put it in terms of a football field, something everyone has seen, and now everyone can understand what a significant problem our state is facing.”
Although the average annual coastal land loss has been about a football field an hour since 1985, in the 1970s that loss rate was much higher, somewhere in the range of a football field every 15 to 37 minutes.
So how could we still have coastal wetlands left?
First, Couvillion says, consider how much wetlands Louisiana had.
In 1932, the Louisiana coastal zone had an area of wetlands equal to 3.72 million football fields. Now, about 25 percent of that, or about 1 million of those football fields, are gone.
“What happens to the remaining 2.8 million football fields remains to be seen,” Couvillion says.
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