Humid periods over western Sahara during the Middle Miocene Climate Transition and their implications on the carbon cycle

Zammit, Ray, Lear, Caroline H. ORCID: https://orcid.org/0000-0002-7533-4430, Lourens, Lucas J., Pearson, Paul N. ORCID: https://orcid.org/0000-0003-4628-9818, Thomas-Sparkes, Amy and Badger, Marcus P. S. 2026. Humid periods over western Sahara during the Middle Miocene Climate Transition and their implications on the carbon cycle. Science Advances 12 (45) , eaec7963. 10.1126/sciadv.aec7963

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Abstract

The Middle Miocene expansion of the Antarctic Ice Sheet coincides with major sedimentological changes in Malta. This interval also saw reorganisations in ocean circulation linked to closure of the Mesopotamian Seaway (MSR-events) and perturbations in the carbon cycle (CM events). The final CM event (CM-6), slightly lags the main glacial phase and remains difficult to interpret due to competing mechanisms and conflicting pCO2 reconstructions. To explore links between cryosphere, circulation, hydroclimate, and the carbon cycle, we present new geochemical records from Malta. Our records show that cryospheric expansion was followed by large, precessionally paced variations in sea-surface salinity and a marked regional increase in biological productivity. The results indicate a shift toward stronger monsoonal influence, delivering enhanced freshwater and nutrient fluxes to the region. This enhanced local biological carbon pump may have acted as a positive feedback to a global CO2 drawdown. However, any contribution to global CO2 drawdown remains tentative and cannot be confirmed without contemporaneous high-resolution open-ocean records.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Earth and Environmental Sciences Schools > Physical, Chemical & Environmental Sciences
Publisher:	American Association for the Advancement of Science
ISSN:	2375-2548
Date of First Compliant Deposit:	12 November 2026
Date of Acceptance:	23 September 2026
Last Modified:	12 Nov 2026 14:45
URI:	https://orca.cardiff.ac.uk/id/eprint/190889

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