Deception and the big "IF"

In "Protecting Many Species to Help Our Own" (NY Times, June 1, 2012), Richard Pearson wrote nearly the whole of his opinion piece under the cover of an "if:"  "if all species listed as threatened on the Red List were lost over the coming century, and that rate of extinction continued, we would be on track to lose three-quarters or more of all species within a few centuries." (the Red List is maintained by the International Union for Conservation of Nature. The statement is attributed to an article in Nature: "Has the Earth’s sixth mass extinction already arrived?" Nature 471, 51–57 (03 March 2011).)

The problem is that the article is accompanied by graphics concerning species extinction that seem to make it very clear that rate of species extinction is nowhere near the rate suggested by "all in Red List lost over the coming century."  Using the graphics figures for estimated extinctions in the past 500 years and the total number of known species in each category, we see that the extinction rate is more typically 1 – 2% in the last 500 years.  We can't assume that endangered species are lost at a vastly faster pace than this because we don’t know what levels of "endangered" might be “normal” or at least inconsistent with a catastrophic loss of species. Surely there are always some species in danger, and it’s quite possible that some species might remain for many centuries—or might always be—in an endangered state.
Nonetheless, by using the "if" clause, the article creates the misimpression that scientists are predicting a mass extinction.  So remember, when you see that "IF,"  it means "all this may be wrong:."

NOTE: My criticism is targeted to Dr. Pearson's piece, which does a poor and slanted job of summarizing what the Nature article says.  The Nature article does present a more cogent--and cautious--argument.