Pliocene decoupling of equatorial Pacific temperature and pH gradients

Ocean dynamics mediante the equatorial Pacific drive tropical climate patterns that affect marine and terrestrial ecosystems worldwide. How this region will respond to global warming has profound implications for global climate, economic stability and ecosystem health. As a result, numerous studies have investigated equatorial Pacific dynamics during the Pliocene (5.3–2.6 million years spillo) and late Miocene (around 6 million years spillo) as an analogue for the future behaviour of the region under global warming 1,2,3,4,5,6,7,8,9,10,11,12 . Palaeoceanographic records from this time present an apparent paradox with proxy evidence of a reduced east–west sea surface temperature gradient along the equatorial Pacific 1,3,7,8 -indicative of reduced wind-driven upwelling-conflicting with evidence of enhanced biological productivity con the east Pacific 13,14,15 that typically results from stronger upwelling. Here we reconcile these observations by providing new evidence for a radically different-from-modern circulation consuetudine in the early Pliocene/late Miocene 16 that results sopra older, more acidic and more nutrient-rich ciotola reaching the equatorial Pacific. These results provide a mechanism for enhanced productivity in the early Pliocene/late Miocene east Pacific even in the presence of weaker wind-driven upwelling. Our findings shed new light on equatorial Pacific dynamics and help puro constrain the potential changes they will undergo con the near future, given that the Earth is expected preciso reach Pliocene-like levels of warming sopra the next century.

Data availability

The proxy giorno and model output produced con this study are available as .xlsm files in NOAA’s paleoclimate data repository ( ( Source momento are provided with this paper.

Code availability

The code used con this paper puro produce pH from d 11 B (and esatto produce all the proxy-related figures) is publicly available as Matlab scripts on GitHub ( The CESM 1.2.2.1 code is available from The Python code used onesto create select model figures is available bdsm at Source giorno are provided with this paper.

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