There is no simple answer "to explain the exceptional phenomena, sometimes deadly, observed both in Europe and the United States, Australia and Latin America, said Jerome Lecou, forecaster engineer at Météo-France. "It was a combination" of factors, approves climatologist Herve Le Treut. The El Niño weather phenomenon plays an "obvious" role in some of the phenomena observed on the planet, notes Hervé Le Treut.
El Nino, which occurs every four to seven years on average, is caused by a change in direction of the trade winds over the equatorial Pacific. The warm surface waters, which normally accumulate in the eastern Pacific, moving westward, resulting in increased rainfall on the west coast of America and more droughts in South-east Asia and Australia.
It "strongly affects the climate of the United States currently," "it is the major cause" of what is happening, says Hervé Le Treut. Deadly tornadoes in Texas, unusual in this season, as the softness observed in the northeast of the country is partly due to this phenomenon, he adds.
The 2015 El Niño episode, the most powerful in 100 years
El Niño is a natural phenomenon but the 2015 episode is "probably the strongest in the last 100 years," says Jérôme Lecou. The World Meteorological Organization (WMO), a UN agency, warned in November that it would gain in intensity by the end of the year. This "El Niño event extremely powerful" example explains "particularly intense floods of Paraguay side and the north of Argentina," said Jerome Lecou. The very hot weather in Australia also match "quite logically El Niño periods"
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