Study assesses long-term costs of El Niño, with losses amounting to trillions of dollars. Most of the losses were borne by the world's poorest countries in the tropics.
El Niño is a climate phenomenon that occurs over periods of 4 to 12 years in the Pacific Ocean. Forecasters expect El Niño events to return by the end of this year, with fears growing that the event could be strong as sea surface temperatures rise particularly in Pacific Ocean and will have a significant impact on global temperatures.