2025-01-01 カーディフ大学
＜関連情報＞
- https://www.cardiff.ac.uk/news/view/2887586-past-climate-change-shifts-ocean-currents-and-winds,-altering-heat-and-carbon-exchange-in-the-southern-ocean,-study-finds
- https://www.science.org/doi/10.1126/sciadv.adp1692
過去190万年間にアフリカの南で変動した南極循環極海流 Shifting Antarctic Circumpolar Current south of Africa over the past 1.9 million years
Aidan Starr, Ian R. Hall, Stephen Barker, Alexandra Nederbragt, […], and Sidney R. Hemming
Science Advances Published:1 Jan 2025
DOI:https://doi.org/10.1126/sciadv.adp1692
Abstract
The Antarctic Circumpolar Current (ACC) dominates the transfer of heat, salt, and tracers around the Southern Ocean (SO), driving the upwelling of carbon-rich deep waters around Antarctica. Paleoclimate reconstructions reveal marked variability in SO circulation; however, few records exist coupling quantitative reconstructions of ACC flow with tracers of SO upwelling spanning multiple Pleistocene glacial cycles. Here, we reconstruct near-bottom flow speed variability in the SO south of Africa, revealing systematic glacial-interglacial variations in the strength and/or proximity of ACC jets. These are superimposed by warmer-than-present “super-interglacials,” whereby extreme slowdown in the midlatitude ACC (41°S) is opposed by faster flow at higher latitudes (>54°S), implying poleward strengthening of the ACC. Coupled with reconstructions of the subsurface-deep stable carbon isotope gradient, we show that the reorganization of ACC coincides with the upwelling of isotopically light deep waters around Antarctica, likely contributing to the interglacial rise in atmospheric carbon dioxide (CO2) levels.
