Subsurface Heat Channel Drove Sea Surface Warming in the High‐Latitude North Atlantic During the Mid‐Pleistocene Transition

Abstract

Between 1.2 and 0.6 Ma, the character of the glacial/interglacial cyclicity shifted from a 41-kyr period to the ∼100-kyr long, saw-toothed cycles characteristic of the Late Pleistocene (Imbrie et al., 1993;Ruddiman et al., 1989). This cyclicity shift involved profound changes in the climatic system such as larger glacial ice-sheets (Berger & Jansen, 1994;Raymo, 1997), an abrupt drop in glacial atmospheric CO 2 (Hönisch et al., 2009), and more pronounced precession pacing of the glacial/interglacial rhythm (Imbrie et al., 1993). Although there have been numerous studies on the Mid-Pleistocene Transition (MPT) (e.g., Clark et al., 2006;McClymont et al., 2013), the mechanisms responsible for the cyclicity shift in the absence of significant change in the orbital configuration remain elusive.

Phylogeography of Paramuricea: The Role of Depth and Water Mass in the Evolution and Distribution of Deep-Sea Corals

“…This transition period was marked by changes in deep water formation and ocean circulation (Pena and Goldstein, 2014;Poirier and Billups, 2014). In addition, there was increased warming at depth and outflow of Mediterranean Outflow Water from the Mediterranean Sea (Catunda et al, 2021). Changes in deep ocean circulation over the past 1 million years could have sparked the spread and diversification of Paramuricea throughout the deep North Atlantic.…”

Moist and warm conditions in Eurasia during the last glacial of the Middle Pleistocene Transition

“… 3 ) and provide evidence for the high production of warm thermocline waters off Iberia. Atmospheric moisture provided by the accumulation of warm subtropical waters in the mid-latitude eastern North Atlantic could have contributed through the westerlies to the recorded extended mild-humid and forested conditions in central and South-East Europe from MIS 21 to 17 3 , 5 . Surprisingly, the subduction of warm waters to thermocline level during MIS 18 was similar and even stronger compared to both interglacials MIS 17 and 19, respectively, despite that insolation 26 , summer energy 27 , atmospheric CO 2 concentrations 28 and relative sea level 29 , 30 were lower during MIS 18 (Fig.…”

“…Imbrie et al’s conceptual model 2 shows that the growth and decay of ice-sheets amplify, through albedo, winds and ocean mass properties, the system’s initial modest responses to orbital forcing by changing the transport of heat to boreal latitudes and atmospheric CO 2 concentration. At the end of the MPT (Marine Isotope Stage-MIS 19 to 17, ~800–670 ka), which is marked by the manifestation of large continental ice-sheets, paradoxical responses are observed with warm sea surface temperatures (SST) in the North Atlantic mid-latitudes generating excess moisture that fuelled ice-sheet growth in Europe and further north 3 – 5 . This climatic evolution culminated in the maximum southern extent of the Eurasian inland ice-sheets during MIS 16 at ~650 ka 6 contemporaneously with a shift to greater ice accumulation in North America 7 .…”

Palaeontological evidence for community-level decrease in mesopelagic fish size during Pleistocene climate warming in the eastern Mediterranean

“…Cold-water (temperate and subpolar) mesopelagic species show a higher relative abundance in the glacial than in the interglacial assemblages. In the Early–Middle Pleistocene Transition, North Atlantic subsurface waters experienced warming phases during glacials after MIS 24 due to pulses of increased outflow of Mediterranean waters [73], which would enhance water mixing and facilitate the functional connectivity between the mesopelagic fish populations of the two regions. This pattern may explain the establishment of subpolar species in the Mediterranean during Middle and Late Pleistocene glacials [11,12,58,59] and the higher relative abundance of cold-water species in MIS 20 and MIS 18 observed in this study.…”