A new study shows that global warming has likely made El Niños and La Niñas "more frequent and more extreme."

Global warming is likely to have intensified a climate pattern in the Pacific since the 1960s that has caused extreme droughts, floods and heat around the world, according to a new study. Scientists say they have shown for the first time that greenhouse gas emissions are already likely to make El Niños and La Niñas more severe. Shifts in ocean temperatures and atmospheric conditions in the Pacific—known as the El Niño Southern Oscillation (Enso)—affect the world's weather, threaten food supplies, spread disease, and affect societies and ecosystems. Scientists tried to find out whether adding greenhouse gases to the atmosphere - trapping huge amount of heat in the ocean – has already changed Enso. But because the system has natural fluctuations lasting decades, and actual observations were too rare, the scientists instead looked at more than 40 climate models, analyzed in several ways. Dr Wenju Cai, lead author studies from Australia's CSIRO science agency, said the models showed a "human fingerprint" from the 1960s. That meant climate change likely made both El Niños and La Niñas "more frequent and more extreme," he said.(Graham Readfearn)