Persistent eastern equatorial Pacific Ocean upwelling since the warm Pliocene

• 成果类型: Article
• 署名作者: Rafter, Patrick A.; Farmer, Jesse R.; Martinez-Garcia, Alfredo; Ravelo, Ana Christina; Karnauskas, Kristopher B.; Batista, Fabian C.; Bernasconi, Stefano M.; Ren, Haojia; Auderset, Alexandra; Haug, Gerald H.; Sigman, Daniel M.
• 署名单位: State University System of Florida; University of South Florida; University of California System; University of California Irvine; University of Massachusetts System; University of Massachusetts Boston; Princeton University; Max Planck Society; University of California System; University of California Santa Cruz; University of Colorado System; University of Colorado Boulder; University of Colorado System; University of Colorado Boulder; Swiss Federal Institutes of Technology Domain; ETH Zurich; National Taiwan University; University of Southampton; NERC National Oceanography Centre
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-8075; 1095-9203
• DOI: 10.1126/science.ads8720
• 发表日期: 2025-10-02
• 页码: eads8720
• 关键词: tropical pacific; CARBONIC-ACID; nitrogen-fixation; isotopic analysis; temperature; seawater; constants; EVOLUTION; nitrate; teleconnections

摘要

Upwelling generates a nutrient-rich cold tongue in the eastern equatorial Pacific Ocean (EEP), with impacts on global climate, oceanic biological productivity, and the carbon cycle. The cold tongue was reduced during the Pliocene Epoch, a feature attributed to weaker upwelling and an associated deepening of the surface mixed layer in the EEP. Here, we report nitrogen-isotope evidence that modern-like upwelling occurred in the EEP during the Pliocene and has persisted over the past 5 million years. We explain the reduced Pliocene cold tongue as an expression of the reduced temperature difference between surface and subsurface waters in the tropical Pacific. The attendant reduction in the vertical density gradient may have maintained EEP upwelling despite the expected slackening of the trade winds under Pliocene warmth.