Buchanan P. J. auteur aut IRD Aumont Olivier auteur aut IRD Bopp L. auteur aut IRD Mahaffey C. auteur aut IRD Tagliabue A. auteur aut IRD text journalArticle eng text/pdf reformatted digital access The open ocean nitrogen cycle is being altered by increases in anthropogenic atmospheric nitrogen deposition and climate change. How the nitrogen cycle responds will determine long-term trends in net primary production (NPP) in the nitrogen-limited low latitude ocean, but is poorly constrained by uncertainty in how the source-sink balance will evolve. Here we show that intensifying nitrogen limitation of phytoplankton, associated with near-term reductions in NPP, causes detectable declines in nitrogen isotopes (delta N-15) and constitutes the primary perturbation of the 21st century nitrogen cycle. Model experiments show that similar to 75% of the low latitude twilight zone develops anomalously low delta N-15 by 2060, predominantly due to the effects of climate change that alter ocean circulation, with implications for the nitrogen source-sink balance. Our results highlight that delta N-15 changes in the low latitude twilight zone may provide a useful constraint on emerging changes to nitrogen limitation and NPP over the 21st century. specialized 032 021 12 1 6214 [9 ] 2021 https://www.documentation.ird.fr/hor/fdi:010083323 10.1038/s41467-021-26552-w [F B010083323] https://www.documentation.ird.fr/hor/fdi:010083323 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2021-12/010083323.pdf IRD - Base Horizon / Pleins textes 2021-12-03 2025-02-24 fdi:010083323 fre