El Niño Event Declared

Tuesday 12th May 2015 by theWeather Club

Image: Before an El Niño event the trade winds weaken leading to a reduction in the upwelling of cold water in the ocean, thus opening the way for warmer tropical waters in the eastern Pacific. 

According to Australia’s Bureau of Meteorology, a potentially "substantial" El Niño event has begun in the tropical Pacific for the first time in five years.

El Niño is a warming of the Pacific Ocean as part of a complex cycle linking atmosphere and ocean. Equatorial trade winds in the Pacific weaken or even reverse their normal east-to-west pattern. Rainfall shifts eastwards away from Australia and south-east Asia, while countries on the eastern Pacific fringe receive more rain than usual. (Read more about El Niños here)

This El Niño is still in its early stages, but has the potential to disrupt weather patterns and cause extreme weather around the world, including droughts and flooding. Indeed, El Niños are linked with monsoons in Southeast Asia, heavy rainfall in South America, the Galapagos Islands and California, reduced rainfall in Indonesia, Malaysia and Australia, droughts in southern Australia, the Philippines and Ecuador, blizzards in the United States, heatwaves in Brazil and extreme flooding in Mexico. El Niño also affects global atmospheric circulation features, such as the jet streams. The consequences of El Niños are much less clear for Europe and the UK. 

An El Niño event had been expected during last year's record-breaking temperatures, but failed to emerge. In April 2015, scientists announced that a ‘weak’ El Niño had arrived, but computer models suggested it could strengthen from September onwards, but it was too early to determine with confidence how strong it could be. 

"There's always a little bit of doubt when it comes to intensity forecasts, but across the models as a whole we'd suggest that this will be quite a substantial El Niño event," said David Jones, manager of climate monitoring and prediction at the Bureau of Meteorology.

Extreme El Niño events are predicted to double over the next century. Until recently it was thought that this phenomenon would be relatively unaffected by climate change, but a new study, published in Nature Climate Change, says we’re now likely to see an extreme El Niño every decade.