Enhanced North Pacific subtropical gyre circulation during the late Holocene

The North Pacific Subtropical Gyre circulation redistributes heat from the Western Pacific Warm Pool towards the mid- to high-latitude North Pacific. However, the driving mechanisms of this circulation and how it changed over the Holocene remain poorly understood. Here, we present alkenone-based sea surface temperature reconstructions along the Kuroshio, California and Alaska currents that cover the past ~7,000 years. These and other paleorecords collectively demonstrate a coherent intensification of the boundary currents, and thereby the basin-scale subtropical gyre circulation, since ~3,000–4,000 years ago. Such enhanced circulation during the late Holocene appears to have resulted from a long-term southward migration of the Intertropical Convergence Zone, associated with Holocene ocean cooling. Our results imply that the North Pacific Subtropical Gyre circulation could be weakened under future global warming.
Long-term variability of the North Pacific Subtropical Gyre (NPSG) circulation is not well understood. Here, the authors present data from different boundary currents that shows an enhanced NPSG circulation since ~3000-4000 years ago, linked to a southward migration of the Intertropical Convergence Zone.