AICE Marine Science Practice Exam

The El Niño phenomenon has profound effects on ocean temperatures and currents, which are critical components of the Earth's climate system. During an El Niño event, the warm water in the central and eastern Pacific Ocean shifts eastward, leading to alterations in oceanic and atmospheric circulation patterns. This shift can disrupt typical weather patterns across the globe, causing variations such as increased rainfall in some regions while leading to droughts in others.

The changes in ocean temperatures during El Niño influence marine ecosystems significantly, often resulting in decreased productivity in certain fisheries due to the reduction in upwelling – the process where nutrient-rich water rises to the surface. Additionally, these alterations can affect not only local climates but also global weather systems, including monsoons, hurricanes, and even temperature fluctuations far removed from the Pacific.

Options involving increased sea levels globally, a reduction in the number of fish species, or increased nutrient levels in all oceans don't accurately reflect the direct impact of El Niño. While sea levels can rise due to a variety of factors including thermal expansion and ice melt, they are not a direct or significant impact of El Niño itself. Similarly, while there may be localized effects on fish populations as a consequence of changes in temperature and currents, El Niño is more about the immediate influence on