Land-ocean changes on orbital and millennial time scales and the penultimate glaciation

• Published in: Geology
• Main Authors: argari, Vasiliki, Skinner, Luke C., Hodell, David A., Martrat, Belen, Toucanne, Samuel, Grimalt, Joan O., Gibbard, Philip L., Lunkka, Juha Pekka, Tzedakis, Polychronis Chronis
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2015
• Subjects: Bipolar seesaw; Climate oscillation; European ice sheets; Extreme events; Freshwater discharge; Heat transport; Meridional overturning circulations; Natural experiment; Ice Sheet
• Online Access: http://hdl.handle.net/10261/117716; https://doi.org/10.1130/G35070.1

Past glacials can be thought of as natural experiments in which variations in boundary conditions influenced the character of climate change. However, beyond the last glacial, an integrated view of orbital- and millennial-scale changes and their relation to the record of glaciation has been lacking. Here, we present a detailed record of variations in the land-ocean system from the Portuguese margin during the penultimate glacial and place it within the framework of ice-volume changes, with particular reference to European ice-sheet dynamics. The interaction of orbital- and millennial-scale variability divides the glacial into an early part with warmer and wetter overall conditions and prominent climate oscillations, a transitional mid-part, and a late part with more subdued changes as the system entered a maximum glacial state. The most extreme event occurred in the mid-part and was associated with melting of the extensive European ice sheet and maximum discharge from the Fleuve Manche river. This led to disruption of the meridional overturning circulation, but not a major activation of the bipolar seesaw. In addition to stadial duration, magnitude of freshwater forcing, and background climate, the evidence also points to the influence of the location of freshwater discharges on the extent of interhemispheric heat transport. a Environmental Change Research Centre, Department of Geography, University College London, London WC1E 6BT, United Kingdom b Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, United Kingdom c Institute of Environmental Assessment and Water Research (IDAEA), Spanish Council for Scientific Research (CSIC), 08034 Barcelona, Spain d IFREMER, Laboratoire Environnements Sédimentaires, F-29280 Plouzané, France e Department of Geography, University of Cambridge, Cambridge CB2 3EN, United Kingdom f Institute of Geosciences, University of Oulu, Oulu, FIN-90014, Finland No