Closure of the Bering Strait caused Mid-Pleistocene Transition cooling.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 30568245.
- Also identified by DOI 10.1038/s41467-018-07828-0 and PMC identifier 6300599.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
The Mid-Pleistocene Transition (MPT) is characterised by cooling and lengthening glacial cycles from 600-1200 ka, thought to be driven by reductions in glacial CO<sub>2</sub> in particular from ~900 ka onwards. Reduced high latitude upwelling, a process that retains CO<sub>2</sub> within the deep ocean over glacials, could have aided drawdown but has so far not been constrained in either hemisphere over the MPT. Here, we find that reduced nutrient upwelling in the Bering Sea, and North Pacific Intermediate Water expansion, coincided with the MPT and became more persistent at ~900 ka. We propose reduced upwelling was controlled by expanding sea ice and North Pacific Intermediate Water formation, which may have been enhanced by closure of the Bering Strait. The regional extent of North Pacific Intermediate Water across the subarctic northwest Pacific would have contributed to lower atmospheric CO<sub>2</sub> and global cooling during the MPT.