Mid-holocene expansion of the Indian Ocean warm pool documented in coral Sr/Ca records from Kenya

• Verfasst von: Leupold, Maike [VerfasserIn]
• Verfasst von: Pfeiffer, Miriam [VerfasserIn]
• Verfasst von: Watanabe, Takaaki K. [VerfasserIn]
• Verfasst von: Nakamura, Nobuko [VerfasserIn]
• Verfasst von: Reuning, Lars [VerfasserIn]
• Verfasst von: Blume, Alina [VerfasserIn]
• Verfasst von: McClanahan, Tim [VerfasserIn]
• Verfasst von: Mohammed, Mchulla [VerfasserIn]
• Verfasst von: Kiriama, Herman [VerfasserIn]
• Verfasst von: Garbe-Schönberg, Dieter [VerfasserIn]
• Verfasst von: Schröder-Ritzrau, Andrea [VerfasserIn]
• Verfasst von: Zinke, Jens [VerfasserIn]
• Titel: Mid-holocene expansion of the Indian Ocean warm pool documented in coral Sr/Ca records from Kenya
• Verf.angabe: Maike Leupold, Miriam Pfeiffer, Takaaki K. Watanabe, Nobuko Nakamura, Lars Reuning, Alina Blume, Tim McClanahan, Mchulla Mohammed, Herman Kiriama, Dieter Garbe-Schönberg, Andrea Schröder Ritzrau & Jens Zinke
• E-Jahr: 2023
• Jahr: 14 January 2023
• Umfang: 13 S.
• Fussnoten: Gesehen am 05.04.2023
• Titel Quelle: Enthalten in: Scientific reports
• Ort Quelle: [London] : Macmillan Publishers Limited, part of Springer Nature, 2011
• Jahr Quelle: 2023
• Band/Heft Quelle: 13(2023) vom: Jan., Artikel-ID 777, Seite 1-13
• ISSN Quelle: 2045-2322
• DOI: doi:10.1038/s41598-023-28017-0
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: Environmental chemistry
• Sach-SW: Palaeoclimate
• K10plus-PPN: 1841331287

Abstract

Proxy reconstructions suggest that mid-Holocene East African temperatures were warmer than today between 8 and 5 ka BP, but climate models cannot replicate this warming. Precessional forcing caused a shift of maximum insolation from boreal spring to fall in the mid-Holocene, which may have favored intense warming at the start of the warm season. Here, we use three Porites corals from Kenya that represent time windows from 6.55 to 5.87 ka BP to reconstruct past sea surface temperature (SST) seasonality from coral Sr/Ca ratios in the western Indian Ocean during the mid-Holocene. Although the Indian monsoon was reportedly stronger in the mid-Holocene, which should have amplified the seasonal cycle of SST in the western Indian Ocean, the corals suggest reduced seasonality (mean 3.2 °C) compared to the modern record (mean 4.3 °C). Warming in austral spring is followed by a prolonged period of warm SSTs, suggesting that an upper limit of tropical SSTs under mid-Holocene conditions was reached at the start of the warm season, and SSTs then remained stable. Similar changes are seen at the Seychelles. Bootstrap estimates suggest a reduction in SST seasonality of 1.3 ± 0.22 °C at Kenya and 1.7 ± 0.32 °C at the Seychelles. SST seasonality at Kenya corresponds to present-day SST seasonality at 55° E-60° E, while SST seasonality at the Seychelles corresponds to present day SST seasonality at ~ 65° E. This implies a significant westward expansion of the Indian Ocean warm pool. Furthermore, the coral data suggests that SST seasonality deviates from seasonal changes in orbital insolation due to ocean-atmosphere interactions.