Paleoproxy data track how El Niño changes nutrient availability



The 1997–1998 El Niño was one of the strongest on record, and the installation of a widespread sensor network in the Pacific before its onset meant that it was also one of the best studied. The El Niño phase of the El Niño–Southern Oscillation (ENSO) brings reduced upwelling of deeper water and leads to warmer sea surface temperatures in the tropical Pacific Ocean. During the 1997–1998 El Niño, shipboard measurements showed that this reduced upwelling caused nutrient availability in the region to drop by roughly half. However, putting in context the effect of this El Niño on nutrient variability and ocean productivity is difficult because high temporal resolution measurements for earlier El Niño events are in short supply.