PALEOCEANOGRAPHY: Thermohaline circulation crisis and impacts during the mid-Pleistocene transition

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The mid-Pleistocene transition (MPT) marked a fundamental change in glacial-interglacial periodicity, when it increased from ˜41-thousand-year to 100-thousand-year cycles and developed higher-amplitude climate variability without substantial changes in the Milankovitch forcing. Here, we document, by using Nd isotopes, a major disruption of the ocean thermohaline circulation (THC) system during the MPT between marine isotope stages (MISs) 25 and 21 at ˜950 to 860 thousand years ago, which effectively marks the first 100-thousand-year cycle, including an exceptional weakening through a critical interglacial (MIS 23) at ˜900 thousand years ago. Its recovery into the post-MPT 100-thousand-year world is characterized by continued weak glacial THC. The MPT ocean circulation crisis facilitated the coeval drawdown of atmospheric CO2 and high-latitude ice sheet growth, generating the conditions that stabilized 100-thousand-year cycles.

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