What is referred to when cool water is replaced by warm, sterile water in the ocean?

The phenomenon where cool water is replaced by warm, sterile water in the ocean is characterized by El Niño. During an El Niño event, the usual patterns of ocean currents and temperature are disrupted, leading to a significant warming of surface waters in the central and eastern tropical Pacific Ocean. This warming can inhibit the upwelling of colder, nutrient-rich waters from the depths of the ocean. As a result, marine life that thrives in these cooler waters may be negatively impacted, leading to a decrease in biological productivity.

El Niño is part of a larger climatic cycle known as the El Niño-Southern Oscillation (ENSO), which includes both El Niño and its counterpart, La Niña, the latter being associated with cooler ocean temperatures. Understanding these temperature shifts is crucial, as they have wide-ranging impacts not only on marine ecosystems but also on global weather patterns, including precipitation and storm intensity across different regions.