Nigerian poet and novelist Ben Okri wrote, "The magician and the politician have much in common: they both have to draw our attention away from what they are really doing." I wonder if the American Coal Ash Association had similar tricks up its sleeve with a recent graph it produced.
I recently wrote a series of posts on coal ash waste in the United States. In one piece, I examined the fate of the stuff, specifically how much is produced, how much is recycled, and how much is just dumped somewhere. Some of our information came from the American Coal Ash Association (ACAA). (I bet most of you didn't know that there was a coal ash trade group or even that one was needed. Same here, but given the amount of coal ash we produce each year, I now understand why there is one.)
In the graphic below, the ACAA presents the data on:
- how much coal waste (or coal combustion product [CCP], as it's known in the trade) is produced in the United States,
- how much is put to use, and
Take a quick glance at the graph and come on back here.
The blue line (labeled "production") and the orange line (labeled "percent use") lie almost on top of each other, right? I don't know about you, but to me that visual left me with a first impression that virtually all of the coal waste produced was put to use. It was only after a closer look and further research that I finally figured out that in fact only about 40 percent has been used in recent years.
Why the Graphic Is Accurate but Misleading
One of the reasons that the graph is so easily misinterpreted is that the right-hand axis uses a scale that tops out at 50 percent. Coincidence? Maybe, but take a look at the graph below the original (at the bottom of the page).
The Green Grok team redid the graph, using the entire scale: 0 to 100 percent for the right-hand y-axis. Now the percent use runs right next to the amount used, down near the bottom of the graph and way below the production line. In other words, the United States has produced a lot of waste, but only a fraction of it has been put to use.
Which graph gives a more accurate "picture" of how much coal waste is used? Why do you suppose the ACAA chose to use the one they did?
Got a graphic you find confusing or misleading? Give us a shout, and we'll investigate. For those of you interested in such graphic sleuthing, check out our post "Understanding Oil" in which we blue line (in big red corrections) a graphic produced by a well-respected news organization.
ACAA's Coal Ash Graph
The Green Grok's Coal Ash Graph
Bill Chameides, dean of Duke University's Nicholas School of the Environment and a member of the National Academy of Sciences, blogs regularly at theGreenGrok.com. Follow him on Twitter: thegreengrok