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- PP41D-1176: A 0.5-Million-Year Benthic Stable Isotope Record of Climate and Deep North Atlantic Circulation at the Iberian Margin
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Board 1176‚ Hall EFG (Poster Hall)NOLA CC
Author(s):Generic 'disconnected' Message
Macy Matthews, Lamont-Doherty Earth Observatory (First Author, Presenting Author)
Jerry McManus, Columbia U. / LDEO
Celeste Pallone, Massachusetts Institute of Technology
Apollonia Arellano, Lamont -Doherty Earth Observatory
From 800,000 to 300,000 years ago, Earth’s climate experienced some of the coldest and longest ice ages of the Quaternary, punctuated by repeated climate oscillations and rapid transitions into notably warm, CO₂-rich interglacial periods. To elucidate how deep-ocean circulation responded to these climate variations, we analyzed a newly recovered core from the Iberian Margin, located where northern- and southern-sourced deep waters mix at a depth of 3,479 meters. We measured oxygen and carbon isotopes (δ¹⁸O and δ¹³C) from bottom-dwelling foraminifera, whose calcium carbonate shells record the chemical properties of deep waters at the times they lived. By comparing these new isotope records with data from a nearby, shallower site, we reconstructed changes in the vertical structure of the deep ocean throughout varying climatic states. We found that during intense glaciations, the deep ocean became more stratified and stored more carbon, as demonstrated by strong vertical δ¹³C gradients between the sites, whereas the gradients weakened during rapid deglaciations, suggesting less deep-ocean stratification and enhanced ocean-atmosphere carbon exchange. These findings underscore the dynamic role of deep-ocean circulation in amplifying the global impacts of abrupt climate change, while highlighting the challenge of anticipating how the deep ocean will respond to ongoing global warming.
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