Taking Earth's Temperature In "Less Coral to Go Around" [R&D;, December] marine scientist Ove Hoegh-Guldberg says that as a result of global warming, coral reefs as we know them will be gone in 50 years. This kind of sensationalist rhetoric makes me doubt that scientists have the faintest clue about what is happening. During previous warm spells in Earth's history, reefs existed in some form; the exposed rock of prehistoric reefs is visible all over the world. The estimated temperatures during some of these earlier warm periods were comparable to the worst estimates for global warming, and yet somehow the reefs survived.
Ed Puntin—Brigantine, New Jersey
Ove Hoegh-Guldberg responds: The majority of recent scientific evidence has led to the conclusion that reefs as we know them will be gone in 50 years. This is neither a sensational nor an unsupported statement. I refer Discover readers to the Third Assessment Report of the Intergovernmental Panel on Climate Change published last year (www.ipcc.ch) and the extensive scientific literature that supports it. This sobering, qualified account will help readers appreciate the serious nature of the climate-change threat to coral reefs. The reader has also missed the major point of the article. The survival of reefs over geological time is not the problem; the problem is how long coral reefs take to reappear if or when sea temperatures have stabilized. The absence of healthy coral reefs, whether for 10 or 1,000 years, is a serious threat to the millions of people who depend on them.
Hearing Is Believing I am puzzled by Michael Abrams's "Name That Tone" [The Biology of. . .Perfect Pitch, December]. The ability to understand or speak a tonal language like Vietnamese or Mandarin does not require perfect pitch. It requires that one learn to recognize and reproduce small changes in pitch. Meaning is not conveyed by the pitch of the syllable but by the direction the pitch is going. It may well be that speakers of tonal languages are more likely than speakers of nontonal languages to hit pretty much the same pitch all the time. That would make sense, because every voice has a limited range, and the need to vary one's pitch to express meaning may force the speaker to stay within certain limits. But this has nothing to do with perfect pitch—the ability to immediately identify where a particular note lies on the musical scale.
David Clotfelter—Northridge, California
Diana Deutsch, professor of psychology at the University of California at San Diego, responds: Mandarin and Vietnamese tones do have characteristic pitch contours, but they also have characteristic pitch ranges: Both the pitch and the contour of a word in a tone language may be degraded in fluent speech, and the meaning of the word can still be reconstructed from the surrounding context. The article refers to our finding that Mandarin and Vietnamese speakers showed extraordinary pitch consistency in reading the same list of words on different days. This consistency is far too great to be explained by the pitch range of the speaking voice and shows that the speakers were using perfect pitch in enunciating the words. Details of this study, including sound examples, are posted at www.acoustics.org/press/138th/deutsch.htm.
Erratum The temple identified on page 20 of November's R&D; as that of Apollo is the Tholos in the sanctuary of Athena Pronaia.
