Amplifying effects of multiyear La Niña on phytoplankton biomass in the tropical Pacific

Tools

Lin, Lei and Xu, Kun and Tan, Wei and Liu, Jinliang and Chen, Bingzhang and Liu, Dongyan (2026) Amplifying effects of multiyear La Niña on phytoplankton biomass in the tropical Pacific. Limnology and Oceanography Letters, 11 (3). e70143. ISSN 2378-2242 (https://doi.org/10.1002/lol2.70143)

[thumbnail of Lin-etal-LOL-2026-Amplifying-effects-of-multiyear-La-Nina-on-phytoplankton-biomass]
Preview
 Text. Filename: Lin-etal-LOL-2026-Amplifying-effects-of-multiyear-La-Nina-on-phytoplankton-biomass.pdf
Final Published Version
License: Creative Commons Attribution 4.0 logo
Download (17MB)| Preview

Abstract

Traditional views suggest that overall phytoplankton biomass in the tropical Pacific should be proportional to La Niña intensity because of enhanced nutrient supplies from equatorial upwelling associated with La Niña intensity. Here, composite analysis of satellite-derived chlorophyll a (Chl a, a proxy for biomass) data across five multiyear La Niña (M-LN) events (1997–2023) showed a double increase in the tropical Pacific average Chl a in the 2nd/3rd years [La Niña(2)] of M-LN compared to the 1st year [La Niña(1)], despite declining La Niña intensities. This unexpected rise is attributed to a ∼ 1-yr lagged response of the off-equatorial phytoplankton to La Niña/El Niño. The lagged response of off-equatorial Chl a to La Niña(1) superimposed with the immediate response of equatorial Chl a to La Niña(2) amplifies overall Chl a levels during La Niña(2). Simulations from Earth System Models support this mechanism. Our findings imply that increased M-LN events may mitigate warming-induced biomass decline in the tropical Pacific.

ORCID iDs

Lin, Lei, Xu, Kun, Tan, Wei, Liu, Jinliang, Chen, Bingzhang ORCID logoORCID: https://orcid.org/0000-0002-1573-7473 and Liu, Dongyan;
CORE (COnnecting REpositories)