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To: Selectric II who wrote (229943)	2/22/2002 3:14:51 AM
From: KLP	Read Replies (1) \| Respond to of 769667

Speaking of Global Warming: Study: El Nino About 6,000 Years Old By PAUL RECER .c The Associated Press WASHINGTON (Feb. 21) - El Nino, the periodic warming of Pacific Ocean waters that affects the weather worldwide, started about 6,000 years ago, according to a study of ancient fish bones. Researchers report Friday in the journal Science that fish bones from refuse left about *6,000 years ago by ancient peoples in Peru show that ocean catfish lived in water that averaged six to seven degrees warmer* than now and that there was little variation in the temperature.** C. Fred T. Andrus of the University of Georgia, the first author of the study, said that if El Nino was occurring at the modern rate, one every two to seven years, then the bones from the fish would have reflected the temperature variation. ''We don't see that,'' said Andrus. ''Our data strengthen the argument that El Nino, as we know it, began relatively recently - since about 6,000 years ago.'' Earlier studies, using chemicals trapped in the shells of ancient mollusks, also suggested that El Nino was absent thousands of years ago, but that work was not widely accepted by others. Andrus said the new study supports the earlier findings. During non-El Nino times, deep, cold Pacific waters well up to the surface off the South American coast, bringing up nutrients and chilling the surface waters. When El Nino starts, the upwelling diminishes and the surface waters warm. This changes weather worldwide. For instance, during the 1997-98 El Nino, there was flooding in California, heavy rains across Texas and the southeast, and mild winters in western Canada. Andrus said that water temperatures off Peru were warmer 6,000 years ago and the climate was more stable. The climate did not experience the rapid changes typically caused by El Nino. ''Given the enormous global impact of El Nino, it's important to understand that climate is a naturally variable system and that just 6,000 years ago El Nino was less frequent,'' said Andrus. Amy Clement, a University of Miami physical oceanographer and climate researcher, said that the Andrus finding is important because it combines physical evidence with other observations to search for an understanding of the ancient climates. But she said the work is not strong enough to draw firm conclusions about El Nino's history. ''It raises questions that need to be tested in computer models,'' said Clement. ''The work contradicts some of the existing climate models.'' In the study, Andrus and his colleagues analyzed the deposition of oxygen isotope 18 in the ear bones - called otoliths - of a species of ocean catfish that have lived off the coast of Peru for thousands of years. The fish's ear bones grow a little bit each year, leaving marks rather like tree rings. The amount of oxygen-18 deposited in the bone marks directly reflects the temperature of the water where the fish lived during the period that the bone was growing. The fish typically live about eight years. Andrus said the researchers captured modern catfish and showed that their ear bones carried the chemical signature of the 1997-98 El Nino. In warmer waters, more oxygen-18 is deposited. The researchers then analyzed 12 otoliths recovered from the refuse piles of ancient peoples who lived along the Peruvian coast and regularly feasted on the catfish. The refuse heaps where the bones were found were age-dated at 6,200 to 6,400 years. Andrus said that out of the dozen otoliths analyzed, the researchers found suggestions of only two El Nino events. If the phenomenon had been as common then as now, he said, each of the otoliths in the catfish, which typically live about eight years, should have borne evidence of a water temperature change caused by El Nino. AP-NY-02-21-02 1553EST Copyright 2002 The Associated Press. The information contained in the AP news report may not be published, broadcast, rewritten or otherwise distributed without the prior written authority of The Associated Press. All active hyperlinks have been inserted by AOL.