Cause of El Nino

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- The warming of surface waters in the central and eastern Pacific Ocean disrupts the usual atmospheric circulation patterns in the region. The trade winds in the Pacific Ocean blow from east to west. These winds push warm surface water towards Asia, piling it up in the western Pacific. In the eastern Pacific, near South America, colder water from deeper layers rises to the surface, a process known as up-welling. To be specific, the trade winds in the equatorial Pacific weaken or change direction, disrupting the typical westward flow of warm surface waters.

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- During an El Niño event, these trade winds weaken or may reverse. When these winds diminish, the eastern movement of warm water across the Pacific towards South America is less impeded. Warm water from the western Pacific moves eastward across the equatorial Pacific, disrupting the usual up-welling of cold, nutrient-rich water along the western coast of South America

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- As a result of weaker trade winds, the warm water that is typically concentrated in the western Pacific spreads back towards the east. This eastward movement of warm water across the equatorial Pacific leads to an increase in sea surface temperatures in the central and eastern Pacific. Moreover, El Niño's warmer ocean temperatures and altered atmospheric circulation can cause various global weather impacts, such as increased rainfall in some areas, droughts in others, and disturbances to marine ecosystems.