The world according to moss.

Moss may be mute, but it has quite a story to tell about changes in Earth's climate, according to researchers who studied a peat bo in Tierra del Fuego, at the tip of South America. Because the cool weather of this region prevents decay, mosses and other plants have piled layer upon layer in the bog, recording information about the climate during the last 14,000 years, say Ray Kenny of New Mexico Highlands University in Las Vegas and co-workers at the University of Colorado at Boulder.

To track ancient conditions, the researchers analyzed the ratio of two hydrogen isotopes within the moss. That ratio indicates the temperature of precipitation taken up by the plants. The scientists believe that the moss data offer clues about global fluctuations in climate because they match information obtained from ice in Antarctica and Greenland, suggesting that all three sites have recorded the same events.

Because scientists can date the layers of moss with the carbon-14 method, they can pinpoint the timing of such climate shifts, something that cannot be done as easily with ice cores and sea-sediment cores, says Kenny. Moss studies, however, have their own limitations. Scientists can only study bogs in cool regions, and the peat records do not reach nearly as far back as some other forms of climate information.