Millennial meridional dynamics of the Indo-Pacific Warm Pool during the last termination

Abstract

To develop an in-depth understanding of the natural dynamics of the Indo-Pacific Warm Pool (IPWP) during the last deglaciation, stacked north- (N-) and south-IPWP (S-IPWP) thermal and hydrological records over the past 23–10.5 ka were built using planktonic foraminiferal geochemistry data from a new core, MD05-2925 (9.3° S, 151.5° E water depth 1661 m) in the Solomon Sea and eleven previous sites. Ice-volume-corrected seawater δ18O (δ18OSW-IVC) stacks show that S-IPWP δ18OSW-IVC values are indistinguishable from their northern counterparts through glacial time. The N-IPWP SST (sea surface temperature) stacked record features an increasing trend of 0.5 °C ka−1 since 18 ka. Its S-IPWP counterpart shows an earlier onset of temperature increase at 19 ka and a strong teleconnection to high-latitude climate in the Southern Hemisphere. Meridional SST gradients between the N- and S-IPWP were 1–1.5 °C during the Bølling/Allerød period and 1 °C during both Heinrich event 1 and the Younger Dryas, due to a warmer S-IPWP. A warm S-IPWP during the cold events could weaken the southern hemispheric branch of the Hadley cell and reduce precipitation in the Asian monsoon region.