ldeo.columbia.edu
Interglacials of the 41kyr-world and the Middle Pleistocene Transition
Sponsored by PAGES and the LDEO Climate Center
Logistics
Date: 19-21 September 2022
Location: Lamont Doherty Earth Observatory (LDEO) of Columbia University, New York, USA
Type of workshop: In-person and remote participation will be number limited
Overview
The goals of the proposed workshop are to examine whether there are any fundamental differences between interglacials of the 41kyr- and 100kyr-worlds and to assess hypotheses on the causes of the Middle Pleistocene Transition (MPT).
The proposed structure of the workshop is:
Part 1 will address the following questions:
- Does the distinction between 'saw-toothed'-shaped glacial cycles of the 100kyr-world and more 'symmetric' cycles of the 41kyr-world reflect the influence of ice-sheet size?
- What was the duration of interglacials of the 41kyr-world?
- Does the association of bipolar seesaw variability with glacial Terminations extend into the 41kyr-world and, therefore, is the interaction of orbital- and millennial-scale variability a necessary component of deglaciation?
Part 2 will consider hypotheses on the causes of the MPT, including:
- The gradual removal of regolith by land ice changed ice-sheet dynamics and led to the emergence of larger ice sheets by 900 ka; the larger ice-sheets, in turn, led to the skipping of insolation cycles and the appearance of ~ 100-kyr glacial cycles (Clark et al., 2006).
- Long-term cooling starting at ~1.55 Ma led to a gradual rise in the insolation threshold required for deglaciation, which in turn led to an increase of skipped obliquity cycles after 1 Ma; the emergence of longer glacials allowed the accumulation of larger ice-sheets (Tzedakis et al., 2017).
- The combined effect of a long-term decline in CO2 and regolith removal controlled the transition from 41kyr- to 100kyr-world (Willeit et al., 2019).
- Antarctic ice sheet growth (from land-based to marine-based margins) and a weaker AMOC led to CO2 drawdown between 950 and 900 ka, which then led to the increase in NH ice sheets and the 100kyr cycle (e.g., Peña & Goldstein, 2014; Farmer et al., 2019; Ford & Raymo, 2020).
Applications
There will be a limited amount of space available for the workshop.
Expressions of interest should be sent to Baerbel Hoenisch: hoenisch@ldeo.columbia.edu, Jerry McManus: jmcmanus@ldeo.columbia.edu and Chronis Tzedakis: p.c.tzedakis@ucl.ac.uk by 29 April 2022 and should include a short description of research experience on the topic. A track record on the themes of the workshop is essential.
Please indicate whether you are an early career researcher (within 5 years of PhD). Notifications will be sent in early May.
We particularly welcome applications from early-career researchers and from those based in developing economies working on relevant topics (partial financial support will be provided, subject to availability).
More information
To contact the local organizers directly, you can email Baerbel Hoenisch: hoenisch@ldeo.columbia.edu and/or Jerry McManus: jmcmanus@ldeo.columbia.edu directly.
For further details, please contact a member of the QUIGS working group leadership team: https://pastglobalchanges.org/science/wg/quigs/people
For more information on the QUIGS working group, visit the website: https://pastglobalchanges.org/science/wg/quigs/intro