What is El Niño?
El Niño is a complex climate pattern characterized by an unusual warming of the ocean surface waters in the central and eastern tropical Pacific Ocean. This warming is part of a larger climate cycle known as the El Niño-Southern Oscillation (ENSO), which significantly influences global weather and climate patterns.
Key Characteristics and Causes
During an El Niño event, the normal east-to-west trade winds across the Pacific weaken or even reverse. This allows the warm surface water that typically accumulates in the western Pacific to spread eastward towards the coast of South America, raising sea surface temperatures. This shift alters atmospheric pressure systems and changes where rainfall occurs, affecting temperatures and precipitation worldwide.
Global Impacts and Examples
El Niño has far-reaching effects on weather. For example, it can lead to increased rainfall and flooding in parts of Peru and Ecuador, while causing droughts in Australia, Indonesia, and parts of India and Africa. It can also bring warmer-than-average winters to the northern United States and Canada, and shift hurricane activity in the Atlantic and Pacific basins.
How it Compares to La Niña
El Niño is one phase of the ENSO cycle; its counterpart is La Niña. While El Niño is associated with warmer-than-average Pacific waters, La Niña involves cooler-than-average ocean temperatures in the same region. La Niña typically brings opposite weather impacts, such as drier conditions in the southern U.S. and wetter conditions in the Pacific Northwest.