El Niño and La Niña (IMAGE) U.S. National Science Foundation Caption El Niño and La Niña "alternate," but both have effects on extreme events such as flooding and fires. Credit USGCRP Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.