We warmly invite you to join the Szczecin Marginal Seas Webinar on January 26, 2023, 2:00 pm (CET) in addition to the regular program of this winter semester.
Please, join our meeting for the lecture:
Last Glacial Maximum lake sediments capture High Arctic surface ocean warming during Heinrich Event 2
to be presented by:
Dr. Willem G. M. van der Bilt
Department of Earth Sciences, University of Bergen,
Bjerknes Centre for Climate Research, Bergen, NO
Abstract
Throughout the Last Glacial period, widespread deposition of Ice Rafted Debris (IRD) marks phases of North Atlantic ice sheet instability during cold Stadial conditions. The causes for these so-called Heinrich Events (HEs) remain debated: while initially attributed to internal ice sheet dynamics, there is mounting evidence for an external ocean-climate forcing. In the latter scenario, ice rafting is thought to be driven by basal melt from a build-up of sub-surface heat in response to weakening ocean circulation. However, coeval shifts from perennial to seasonal sea ice conditions suggest that some heat may have escaped to the surface. We strengthen this notion, by presenting biomarker-based evidence for atmospheric warming from a unique Last Glacial Maximum (30-20 ka BP) lake sediment sequence from High Arctic Svalbard. Alkenone-derived changes in temperature (UK37) and hydroclimate (δD) indicate a rapid shift towards warmer surface conditions and more locally sourced precipitation at the onset of HE 2. These findings are supported by XRF evidence for lake water stratification and a shift towards n-alkane distributions indicative of less arid conditions. In conclusion, our data suggests that climate-forced Arctic ice sheet instability during HEs was triggered from below as well as above.
The seminar will be held in a hybrid form, in room 111 building Mickiewicza 16 and parallel on the MS Teams platform.
The meeting room will be open from 1:30 pm (CET), but the seminar will begin at 2:00 pm (CET).
To join the meeting please use the link:
https://teams.microsoft.com/l/meetup-join/19%3a0ee21c3b364e4709810bc45b7fbb4284%40thread.tacv2/1674495333830?context=%7b%22Tid%22%3a%22af892dd6-4563-4455-9c05-a398a43f2362%22%2c%22Oid%22%3a%221e9df312-5fc1-4e40-bc0d-ab7f66ee7bd8%22%7d
Meeting ID: 360 349 589 998
Access code: mXMpCg