This isn’t the first time I’ve complained about innumeracy, and I’m sure it won’t be the last. Just to get off on the right foot, let me give the definition of the word from thesite innumeracy.com:

A term meant to convey a person’s inability to make sense of the numbers that run their lives. Innumeracy was coined by cognitive scientist Douglas R Hofstadter in one of his Metamagical Thema columns for Scientific American in the early nineteen eighties. Later that decade mathematician John Allen Paulos published the book Innumeracy. In it he includes the notion of chance as well to that of numbers.

The example of innumeracy found in this post is somewhat more interesting than most, because it comes from a source that really should know better: Discover Magazine.

In the July 2008 of Discover Magazine, I was reading an article titled Ocean Acidification: A Global Case of Osteoporosis, and saw this quote:

One such event occurred 55 million years ago at the so-called Paleocene-Eocene Thermal Maximum (PETM), when 4.5 million tons of greenhouse gases were released into the atmosphere.

Now, we’re supposedly talking about an event in which so much greenhouse gas was emitted that extraordinary climate change occurred. Is 4.5 million tons really a lot? Checking the Wikipedia article on greenhouse gas emissions gave this interesting quote:

According to a preliminary estimate by the Netherlands Environmental Assessment Agency, the largest national producer of CO2 emissions since 2006 has been China with an estimated annual production of about 6200 megatonnes. China is followed by the United States with about 5,800 megatonnes.

So the US and China produce 12 million billion tons of CO2 in a year, while the PETM produced 4.5 million tons. And the PETM was a major event that we are blowing away every year, year after year? Something is not right here.

Check the Source

Fortunately, Discover references the source of their information right on the web page, and quick check of the paper shows what the actual number is supposed to be:

Atmospheric temperatures inferred from surface ocean (references in Zachos et al. [2005]) and terrestrial (e.g., Wing et al. [2005]) proxies warmed by 5 – 9° C globally during the PETM. Warming was closely associated with the release of between ~1500 and 4500 Gt of carbon to the ocean and atmosphere, resulting in large but poorly quantified increases in atmospheric CO2 levels [Zachos et al., 2005].

Okay, so in my book, Gt means Gigatonne, and regardless of whether we are using English or Metric units, that’s going to be measured in billions, not millions of tons.

How did Discover take this number from the paper and mangle it by three orders of magnitude? We’ll never know. But avoid innumeracy, try to be aware of just how big the earth is, and realize that what seem like big numbers don’t always do it justice.