Fig. 4: Conceptual diagram depicting climatic dynamics surrounding the termination of HS4.
From: Onset and termination of Heinrich Stadial 4 and the underlying climate dynamics
a, b show centennial-scale changes in the Amazon River runoff and the SWW position prior to the abrupt HS4 termination in Greenland. The SWW and STF shifted poleward, which enhanced the Agulhas Current off the southern coast of South Africa, increased the Agulhas leakage and thus the salt/heat transport from the Indo-Pacific Ocean. Striking reduction of the Amazon runoff into the Atlantic Ocean, inferred from SAM records, increased the sea-surface salinity in the Amazon plume region (APR) and therefore increased the northward salt transport by the mean oceanic circulation (red route). Both processes ultimately contributed to AMOC strengthening. ACC Antarctic circumpolar current, SWW Southern Westerly wind, STF subtropical front, SAF Subantarctic front, PF Polar front. White dashed line in a depicts the modern APR, while the APR in b is rather arbitrary. Red dots show locations of SAM speleothem records of the South American Monsoon. Black dots show ice-core locations. The map was created using ArcGIS software and the world map background data are from the Environmental Systems Research Institute (ESRI, https://www.arcgis.com/apps/mapviewer/index.html?layers=10df2279f9684e4a9f6a7f08febac2a9).
