Preprints
https://doi.org/10.5194/cp-2023-81
https://doi.org/10.5194/cp-2023-81
04 Oct 2023
 | 04 Oct 2023
Status: a revised version of this preprint was accepted for the journal CP and is expected to appear here in due course.

New estimation of critical insolation – CO2 relationship for triggering glacial inception

Stefanie Talento, Matteo Willeit, and Andrey Ganopolski

Abstract. It has been previously proposed that glacial inception represents a bifurcation transition between interglacial and glacial states, and is governed by the non-linear dynamics of the climate-cryosphere system. To trigger glacial inception, the orbital forcing (defined as the maximum of summer insolation at 65° N and determined by Earth’s orbital parameters) must be lower than a critical level, which depends on the atmospheric CO2 concentration. While paleoclimatic data do not provide a strong constraint on the dependence between CO2 and critical insolation, its accurate estimation is of fundamental importance for predicting future glaciations and the effect that anthropogenic CO2 emissions might have on them.

In this study, we use the novel Earth system model of intermediate complexity CLIMBER-X with interactive ice sheets to produce a new estimation of the critical insolation – CO2 relationship for triggering glacial inception. We perform a series of experiments in which different combinations of orbital forcing and atmospheric CO2 concentration are maintained constant in time. We analyse for which combinations of orbital forcing and CO2 glacial inception occurs and trace the critical relationship between them, separating conditions under which glacial inception is possible from those where glacial inception is not materialised. We also provide a theoretical foundation for the proposed critical insolation – CO2 relation.

We find that the use of the maximum summer insolation at 65° N as a single metric for orbital forcing is adequate for tracing the glacial inception bifurcation. Moreover, we find that the temporal and spatial patterns of ice sheet growth during glacial inception are not always the same but depend on the critical insolation and CO2 level. The experiments evidence that during glacial inception, ice sheets grow mostly in North America, and only under low CO2 conditions ice sheets are also formed over Scandinavia. The latter is associated with a weak Atlantic Meridional Overturning Circulation (AMOC) for low CO2. We find that the strength of AMOC also affects the rate of ice sheet growth during glacial inception.

Stefanie Talento, Matteo Willeit, and Andrey Ganopolski

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2023-81', Anonymous Referee #1, 18 Oct 2023
    • AC1: 'Reply on RC1', Stefanie Talento, 19 Dec 2023
  • RC2: 'Comment on cp-2023-81', Anonymous Referee #2, 06 Nov 2023
    • AC2: 'Reply on RC2', Stefanie Talento, 19 Dec 2023

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on cp-2023-81', Anonymous Referee #1, 18 Oct 2023
    • AC1: 'Reply on RC1', Stefanie Talento, 19 Dec 2023
  • RC2: 'Comment on cp-2023-81', Anonymous Referee #2, 06 Nov 2023
    • AC2: 'Reply on RC2', Stefanie Talento, 19 Dec 2023
Stefanie Talento, Matteo Willeit, and Andrey Ganopolski

Model code and software

Code and data: New estimation of critical insolation – CO2 relationship for triggering glacial inception Stefanie Talento https://doi.org/10.17605/OSF.IO/2MHKY

Stefanie Talento, Matteo Willeit, and Andrey Ganopolski

Viewed

Total article views: 671 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
490 161 20 671 20 14
  • HTML: 490
  • PDF: 161
  • XML: 20
  • Total: 671
  • BibTeX: 20
  • EndNote: 14
Views and downloads (calculated since 04 Oct 2023)
Cumulative views and downloads (calculated since 04 Oct 2023)

Viewed (geographical distribution)

Total article views: 682 (including HTML, PDF, and XML) Thereof 682 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Latest update: 06 May 2024
Download
Short summary
To trigger glacial inception, the summer maximum insolation at high latitudes in the Northern Hemisphere must be lower than a critical value. This value is not constant but depends on the atmospheric CO2 concentration. Paleoclimatic data do not tell enough information to derive the relationship between the critical threshold and CO2. However, the knowledge of such a relation is important for predicting future glaciations and the impact anthropogenic CO2 emissions might have on them.