Spatially contrasted response of Devonian anoxia to astronomical forcing
Gerard, J.; Pohl, A.; Sablon, L.; Huygh, J.; DaSilva, A.; Crucifix, M. (2026). Spatially contrasted response of Devonian anoxia to astronomical forcing. Clim. Past 22(5): 1003-1021. https://dx.doi.org/10.5194/cp-22-1003-2026
In: Climate of the Past. Copernicus: Göttingen. ISSN 1814-9324; e-ISSN 1814-9332, more
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| Author keywords |
earth system model;continental configuration;parameter sensitivity;climate;trigger;phosphorus;transport;patterns;impact;cycle |
| Authors | | Top |
- Gerard, J.
- Pohl, A.
- Sablon, L.
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- Huygh, J.
- DaSilva, A., more
- Crucifix, M., more
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| Abstract |
The Devonian period, spanning from 419 to 359 million years ago, was marked by a warmer-than-present climate and recurring ocean anoxic events, with evidence increasingly suggesting a link between these events and astronomical forcing. Here, we explore how astronomical forcing influences ocean oxygenation by modulating the continental weathering flux of phosphate within a Late Devonian climate framework. To investigate this, we performed transient simulations spanning 1.1 Myr, crossing a 2.4 Myr eccentricity node using the cGENIE Earth system model. These simulations were driven by spatially resolved fluxes of reactive phosphorus from continents, computed using the emulator developed by , trained on GEOCLIM and HadSM3 outputs. Our results provide new evidence supporting eccentricity maxima as a driver of Late Devonian anoxic events. Additionally, global analysis reveals that obliquity variations can leave an imprint on global ocean oxygen levels via their influence on biological productivity, suggesting a potential pathway for obliquity-driven anoxia under greenhouse conditions. Regional analysis revealed pronounced spatial heterogeneity in the biogeochemical response to astronomical forcing. Local ocean circulation emerged as a critical factor in shaping these patterns. The simulations indicate that astronomical forcing can, through its impact on continental weathering fluxes, exert a dominant influence on ocean oxygenation, with regional oxygen concentrations varying by up to 35 % and driving changes in regional anoxic volume of up to 19 %. Finally, these findings help explain why proxy records from different locations may show divergent expressions of astronomical signals, potentially leading to contrasting interpretations of their role in driving ocean anoxia. |
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