Articles | Volume 18, issue 8
Research article
 | Highlight paper
22 Aug 2022
Research article | Highlight paper |  | 22 Aug 2022

Effects of orbital forcing, greenhouse gases and ice sheets on Saharan greening in past and future multi-millennia

Mateo Duque-Villegas, Martin Claussen, Victor Brovkin, and Thomas Kleinen


Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on cp-2022-26', Zhengyu Liu, 03 Apr 2022
    • AC1: 'Reply on CC1', Mateo Duque-Villegas, 10 May 2022
  • RC1: ' Review by Chris Brierley (UCL) of cp-2022-26', Chris Brierley, 05 Apr 2022
    • AC2: 'Reply on RC1', Mateo Duque-Villegas, 10 May 2022
  • RC2: 'Comment on cp-2022-26', Anonymous Referee #2, 18 Apr 2022
    • AC3: 'Reply on RC2', Mateo Duque-Villegas, 09 Jun 2022
  • RC3: 'Comment on cp-2022-26', Anonymous Referee #3, 25 Apr 2022
    • AC4: 'Reply on RC3', Mateo Duque-Villegas, 09 Jun 2022

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision
ED: Publish subject to minor revisions (review by editor) (09 Jun 2022) by Ran Feng
AR by Mateo Duque-Villegas on behalf of the Authors (01 Jul 2022)  Author's response    Author's tracked changes    Manuscript
ED: Publish as is (17 Jul 2022) by Ran Feng
The alternation of vegetated and arid Sahara has long attracted wide interest in paleoclimate field. This study presents a suite of highly interesting simulations of the past 190,000 years with a state-of-the-art Earth system model of intermediate complexity. This set of experiments are rigorously designed and analyzed, which allow the authors to make an important discovery of what controls the onset of African Humid Period: i.e. a threshold in orbital forcing, which decreases at elevated CO2 concentration. Moreover, maximum rates of change in simulated vegetation extent during the onset and termination of African Humid Period correlate strongly with the rates of change of the orbital forcing. A factor separation analysis further confirms the dominant role of the orbital forcing in driving the amplitude of precipitation and vegetation extent for past African Humid Period. These results have broad implications to future variability of Sahara climate in response to orbital forcing changes and non-linear earth system feedbacks.
Short summary
Using an Earth system model of intermediate complexity, we quantify contributions of the Earth's orbit, greenhouse gases (GHGs) and ice sheets to the strength of Saharan greening during late Quaternary African humid periods (AHPs). Orbital forcing is found as the dominant factor, having a critical threshold and accounting for most of the changes in the vegetation response. However, results suggest that GHGs may influence the orbital threshold and thus may play a pivotal role for future AHPs.