Revisiting the mid-Pleistocene transition ocean circulation crisis

Area of Science:

• Paleoceanography
• Climate Science
• Geochemistry

Background:

• The mid-Pleistocene transition (~1.25 to 0.85 million years ago) marked a significant change in glacial-interglacial climate cycles.
• A leading hypothesis proposed a deep ocean circulation crisis around 0.90 Ma as the cause of the mid-Pleistocene transition.

Purpose of the Study:

• To investigate the role of deep ocean circulation changes during the mid-Pleistocene transition.
• To test the hypothesis of a circulation "crisis" at approximately 0.90 Ma.

Main Methods:

• Analysis of high-resolution paired neodymium, carbon, and oxygen isotope data.
• Reconstruction of past deep ocean circulation and carbon storage in the South Atlantic Ocean (Cape Basin).

Main Results:

• No evidence for a substantial change in deep ocean circulation across the mid-Pleistocene transition was found.
• Glacial deep ocean variability before and during the early MPT mirrored that of the most recent glacial cycle.
• Developing deep ocean stratification required only modest circulation adjustments for carbon storage.

Conclusions:

• The mid-Pleistocene transition was not driven by a fundamental change or crisis in deep ocean circulation.
• Ocean circulation exhibited stability, with minor adjustments accommodating increased carbon storage through stratification.