What phenomenon is accompanied by unusually warm ocean temperatures in the Pacific Ocean?

The phenomenon characterized by unusually warm ocean temperatures in the Pacific Ocean is known as El Niño. This climate pattern occurs when the typical westward trade winds weaken, allowing warm water from the western Pacific to flow eastward toward the South American coasts. As the sea surface temperatures rise, it can lead to significant changes in weather patterns not only in the Pacific region but also globally, influencing precipitation, temperature, and storm activity in various parts of the world.

In contrast, La Niña is associated with cooler ocean temperatures and intensified trade winds, which typically results in opposite weather patterns to those seen during El Niño. Trade winds themselves refer to the consistent east-to-west winds that can influence ocean temperatures but are not characterized as a phenomenon. Jet streams are high-altitude air currents that also affect weather but are not directly tied to ocean temperature variations in the Pacific. Understanding these distinctions highlights why El Niño is the correct answer in this context.