El Niño Cometh

The meteorological behemoth has arrived on the west coast of USA. But what does this actually mean?

For drought-struck California, not a lot right now. But as we move later into the year, the effect of the weather system might become more extreme.

The El Niño effect is caused by a warming of a band of the Pacific Ocean near the equator, in a complex cycle linking ocean and atmosphere. El Niño is accompanied by high air pressure in the western Pacific and low air pressure in the eastern Pacific. The effects of the weather event are complex and wide reaching, affecting the entire world in different ways throughout the year; it can cause floods and droughts, and affect snowfall later in the year. Five years ago, in the most recent extreme case of the weather effect, there was drastically reduced rainfall in Southeast Asia, Australia, the Philippines and Ecuador, leading to droughts, the USA was hit by blizzards and Mexico was destroyed by flooding.

Sea surface temperature anomalies during the 1997-98 El Nino event. Credit: NASA/NOAA
Sea surface temperature anomalies during the 1997-98 El Nino event. Credit: NASA/NOAA

A strong El Niño effect usually means increased rainfall for Central America and the southwestern US. This year, the effect for Californian farmers just isn’t enough to help after a prolonged drought affecting the region. American scientists described the effect as weak and predicted it wouldn’t bring the rainfall needed. In South America, this might be a good thing since heavy, warm rainfall can affect fish populations vital for food.

However, scientists from Australia have turned the American predictions on their head. They predict that the effect will strengthen over the coming months (especially in September) into a substantial event, potentially causing more meteorological chaos. British scientists are more reserved, commenting that “the likelihood of El Niño is high but its eventual strength in the winter when it has its major impacts worldwide is still unknown. We will know in the summer how strong it is going to be.”

H/T BBC News, HuffPo

Image credit: TOPEX/Poseidon/NASA/CNES

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