Warm waters spreading across the tropical Pacific are driving the buildup of a major El Niño, the World Meteorological Organisation has confirmed, sharpening fears of higher global temperatures and a fresh surge in extreme weather and heavy rainfall in the months ahead. The agency said its forecasting models show an 80% chance that above-average temperatures will be recorded across almost the entire globe from June to August. It also said there is a 90% probability that El Niño’s warming influence will persist and strengthen…