El Nino Is Relatively Recent, Fossils Show

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. Georgia researchers reported in the Feb. 22 issue of 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 6 degrees to 7 degrees warmer than now and that there was little variation in the temperature.

C. Fred T. Andrus of the University of Georgia said that if El Nino was occurring at the modern rate, once 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.”