Scientists are changing how they measure El Niño as rising global temperatures distort long-used data. As global warming heats the entire tropical Pacific, the differences have become harder to detect. Since February 2026, forecasters at the National Oceanic and Atmospheric Administration (NOAA) have introduced a new measuring tool: the Relative Oceanic Niño Index (RONI). The method subtracts warming in the broader Pacific from the core El Niño zone, allowing scientists to capture the true extent of the phenomenon.
Before February, researchers relied on the Oceanic Niño Index, which compared temperatures in a key Pacific region to a 30-year average. A more precise tool could help prevent floods, droughts, and billions in damage across the globe.
El Niño occurs when waters in the tropical Pacific become much warmer than average. Its cooler counterpart, La Niña, can trigger opposite effects.
It greatly impacts ocean temperatures, as well as the speed and strength of ocean currents, marine life, and weather patterns. The El Niño phenomenon occurs at intervals of two to seven years, but it is highly unpredictable.
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