Hennissen J.A.IHead M.JDe Schepper SJEROEN GROENEVELD2022-11-112022-11-11201502773791https://www.scopus.com/inward/record.uri?eid=2-s2.0-84952052100&doi=10.1016%2fj.quascirev.2015.10.010&partnerID=40&md5=7e4619db48d3f8e9866fbe615d79b8a0https://scholars.lib.ntu.edu.tw/handle/123456789/624768Near the Pliocene-Pleistocene (Neogene-Quaternary) boundary during Marine Isotope Stage (MIS) 104 at around 2.6 Ma, the intensification of Northern Hemisphere glaciation (iNHG) was marked by a southward shift of the North Atlantic Current and Arctic Front and a concurrent drop in sea surface temperature (SST) in the mid-latitudes of the North Atlantic. Here we evaluate two Mg/Ca-based sea-surface temperature reconstructions for the 2.78-2.52 Ma interval using the planktonic foraminifera Globigerina bulloides and Globigerinoides ruber (white) sensu stricto as the biotic carriers (SSTbul and SSTrub), and a reconstruction based on the alkenone saturation index (SSTalk). The Mg/Ca-based SST estimates begin to diverge from one another significantly during MIS G3 (~2.66 Ma), culminating during MIS 104 (~2.60 Ma), and remaining distinctly different for the remaining 80 kyr of the studied interval. The magnitude of this divergence (δSSTrub-bul) is caused mainly by a decrease in SSTbul, with SSTrub remaining relatively constant. We attribute this difference to a drop in SST during the early-spring blooming season of G. bulloides that was less pronounced during the late-summer blooming season of G. ruber. Using δSSTrub-bul as a seasonality indicator, we show that seasonality increased significantly owing to a drop in early spring temperatures from MIS 104 onwards, and peaked during glacial episodes. Maximum seasonality occurred during MIS 104 in coincidence with a major expansion of the circum-Atlantic ice sheets, particularly the North American ice sheet. This expansion appears to have had a critical influence on global climate and especially seasonality. © 2015 Elsevier Ltd.North Atlantic; Palaeoclimatology; Paleoceanography; Pliocene; Quaternary; SeasonalityArctic vehicles; Atmospheric temperature; Climate change; Drops; Glacial geology; Glaciers; Submarine geophysics; Surface properties; Surface waters; North Atlantic; Palaeoclimatology; Paleoceanography; Pliocene; Quaternary; Seasonality; Oceanography; glaciation; ice sheet; marine isotope stage; Northern Hemisphere; paleoceanography; paleoclimate; planktonic foraminifera; Pliocene-Pleistocene boundary; reconstruction; sea surface temperature; seasonality; Arctic Ocean; Atlantic Ocean; North Atlantic Current; Foraminifera; Globigerina bulloides; Globigerinoides ruberjournal article10.1016/j.quascirev.2015.10.0102-s2.0-84952052100