Research Data Leeds Repository

Citation

Snoll, Brooke and Ivanovic, Ruza and Gregoire, Lauren and Sherriff-Tadano, Sam and Rome, Yvan (2025) Competing effects of sea ice change control the pace and amplitude of millennial-scale climate oscillations. University of Leeds. [Dataset] https://doi.org/10.5518/1624

Dataset description

Despite an increasing number of climate simulations showing millennial-scale oscillatory regimes, such as Dansgaard-Oeschger cycles, the mechanisms behind past abrupt climate changes remain elusive. Based on previous experiments that simulated such variability under Last Glacial Maximum boundary conditions forced with fixed freshwater snapshots derived from the early last deglaciation ice sheet history, this paper investigates the AMOC oscillatory mechanisms under different climate forcings (i.e., different levels of CO2 concentrations and varying orbital parameters). Our results show that sea ice plays a key role as a pacer, regulating AMOC transitions between strong/interstadial and weak/stadial modes. At lower CO2 levels, sea-ice volume increases and the warm-mode duration is reduced through enhanced summer sea ice melt. In contrast, higher levels of CO2 lead to thinner sea ice and in turn, cooler North Atlantic subsurface temperatures and suppressed oscillations. Orbital changes influence seasonality and localised sea ice dynamics, shortening or lengthening strong AMOC periods based on obliquity variations. These simulations, performed with the HadCM3 general circulation model, show that small climate changes can impact the shape and existence of oscillations in glacial climates, potentially explaining the variability in the periodicity and amplitude of Dansgaard-Oeschger cycles and transitions from weak to strong AMOC states.

Keywords:	Millennial-scale variability, AMOC, general circulation model, convection-advection oscillator, climatic controls
Divisions:	Faculty of Environment > School of Earth and Environment
Related resources:	Location Type https://doi.org/10.5281/zenodo.17177067 Software
License:	Creative Commons Attribution 4.0 International (CC BY 4.0)
Date deposited:	22 Sep 2025 20:06
URI:	https://archive.researchdata.leeds.ac.uk/id/eprint/1462
Additional details Additional details Alternative title: HadCM3 millennial-scale climate oscillations with changes in CO2 and orbit Creators or authors: Creators ORCID Other ID Email Primary affiliation Primary affiliation ID Primary affiliation ID type Secondary affiliation Secondary affiliation ID Secondary affiliation ID type Snoll, Brooke https://orcid.org/0000-0002-3091-4394 University of Leeds https://ror.org/024mrxd33 ror Ivanovic, Ruza https://orcid.org/0000-0002-7805-6018 University of Leeds https://ror.org/024mrxd33 ror Gregoire, Lauren https://orcid.org/0000-0003-0258-7282 University of Leeds https://ror.org/024mrxd33 ror Sherriff-Tadano, Sam https://orcid.org/0000-0002-4378-9166 University of Leeds https://ror.org/024mrxd33 ror Rome, Yvan https://orcid.org/0000-0003-3343-1459 University of Leeds https://ror.org/024mrxd33 ror Type of data: Dataset Research funders: Natural Environment Research Council, Doctoral Training Partnership Panorama Grant numbers: NE/S007458/1 Publication date: 2025 Resource language: English Metadata language: English Publisher: University of Leeds Contact email: earbsn@leeds.ac.uk Last Modified: 25 Sep 2025 07:02

Files

Documentation

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Data

CO2_180ppm [2GB] CO2_180ppm [2GB] CO2_180ppm [2GB] Security: Anyone File name: CO2_180ppm.zip Content type: Data Description: Folder with March sea ice concentration (iceconc), March sea ice thickness (icedepth), AMOC streamfunction (merid), annual and winter mixed layer depth (oceanmixedpf), sea surface temperature (oceansurftemppf), ocean temperature at 50 and 500 metres, and Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 2GB

CO2_180ppm_cont [1GB] CO2_180ppm_cont [1GB] CO2_180ppm_cont [1GB] Security: Anyone File name: CO2_180ppm_cont.zip Content type: Data Description: Folder with ONDJF sea surface salinity (oceansalipf), ocean salinity at 500 and 50 metres depth, annual surface air temperature Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 1GB

CO2_200ppm [2GB] CO2_200ppm [2GB] CO2_200ppm [2GB] Security: Anyone File name: CO2_200ppm.zip Content type: Data Description: Folder with March sea ice concentration (iceconc), March sea ice thickness (icedepth), AMOC streamfunction (merid), annual and winter mixed layer depth (oceanmixedpf), sea surface temperature (oceansurftemppf), ocean temperature at 50 and 500 metres, and Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 2GB

CO2_200ppm_cont [575MB] CO2_200ppm_cont [575MB] CO2_200ppm_cont [575MB] Security: Anyone File name: CO2_200ppm_cont.zip Content type: Data Description: Folder with ONDJF sea surface salinity (oceansalipf), ocean salinity at 500 and 50 metres depth, annual surface air temperature Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 575MB

CO2_210ppm [3GB] CO2_210ppm [3GB] CO2_210ppm [3GB] Security: Anyone File name: CO2_210ppm.zip Content type: Data Description: Folder with March sea ice concentration (iceconc), March sea ice thickness (icedepth), AMOC streamfunction (merid), annual and winter mixed layer depth (oceanmixedpf), sea surface temperature (oceansurftemppf), ocean temperature at 50 and 500 metres, and Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 3GB

CO2_210ppm_cont [1GB] CO2_210ppm_cont [1GB] CO2_210ppm_cont [1GB] Security: Anyone File name: CO2_210ppm_cont.zip Content type: Data Description: Folder with ONDJF sea surface salinity (oceansalipf), ocean salinity at 500 and 50 metres depth, annual surface air temperature Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 1GB

Orbit_10k [1GB] Orbit_10k [1GB] Orbit_10k [1GB] Security: Anyone File name: Orbit_10k.zip Content type: Data Description: Folder with March sea ice concentration (iceconc), March sea ice thickness (icedepth), AMOC streamfunction (merid), sea surface temperature (oceansurftemppf), ocean temperature at 50 and 500 metres Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 1GB

Orbit_10k_cont [2GB] Orbit_10k_cont [2GB] Orbit_10k_cont [2GB] Security: Anyone File name: Orbit_10k_cont.zip Content type: Data Description: Folder with ONDJF sea surface salinity (oceansalipf), ocean salinity at 500 and 50 metres depth, annual surface air temperature Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 2GB

Orbit_10k_cont2 [1GB] Orbit_10k_cont2 [1GB] Orbit_10k_cont2 [1GB] Security: Anyone File name: Orbit_10k_cont2.zip Content type: Data Description: Folder with annual and winter mixed layer depth and March meridional surface ocean velocity (oceanvvel). Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 1GB

Orbit_21.5 [2GB] Orbit_21.5 [2GB] Orbit_21.5 [2GB] Security: Anyone File name: Orbit_21.5k.zip Content type: Data Description: Folder with March sea ice concentration (iceconc), March sea ice thickness (icedepth), AMOC streamfunction (merid), annual and winter mixed layer depth (oceanmixedpf), sea surface temperature (oceansurftemppf), ocean temperature at 50 and 500 metres. Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 2GB

Orbit_21.5k_cont [2GB] Orbit_21.5k_cont [2GB] Orbit_21.5k_cont [2GB] Security: Anyone File name: Orbit_21.5k_cont.zip Content type: Data Description: Folder with ONDJF sea surface salinity (oceansalipf), ocean salinity at 500 and 50 metres depth, annual surface air temperature, and March meridional surface ocean velocity (oceanvvel). Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 2GB

Orbit_30k [1GB] Orbit_30k [1GB] Orbit_30k [1GB] Security: Anyone File name: Orbit_30k.zip Content type: Data Description: Folder with March sea ice concentration (iceconc), March sea ice thickness (icedepth), AMOC streamfunction (merid), annual and winter mixed layer depth (oceanmixedpf), ocean temperature at 50 and 500 metres. Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 1GB

Orbit_30k_cont [1GB] Orbit_30k_cont [1GB] Orbit_30k_cont [1GB] Security: Anyone File name: Orbit_30k_cont.zip Content type: Data Description: Folder with ONDJF sea surface salinity (oceansalipf), sea surface temperature (oceansurftemppf), ocean salinity at 500 and 50 metres depth, annual surface air temperature, and March meridional surface ocean velocity (oceanvvel). Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 1GB

REF [2GB] REF [2GB] REF [2GB] Security: Anyone File name: REF.zip Content type: Data Description: Folder with March sea ice concentration (iceconc), March sea ice thickness (icedepth), AMOC streamfunction (merid), annual and winter mixed layer depth (oceanmixedpf), sea surface temperature (oceansurftemppf), ocean temperature at 50 and 500 metres. Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 2GB

REF_cont [2GB] REF_cont [2GB] REF_cont [2GB] Security: Anyone File name: REF_cont.zip Content type: Data Description: Folder with ONDJF sea surface salinity (oceansalipf), ocean salinity at 500 and 50 metres depth, annual surface air temperature, and March meridional surface ocean velocity (oceanvvel). Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 2GB

REF2 [2GB] REF2 [2GB] REF2 [2GB] Security: Anyone File name: REF2.zip Content type: Data Description: Folder with March sea ice concentration (iceconc), March sea ice thickness (icedepth), AMOC streamfunction (merid), sea surface temperature (oceansurftemppf), ocean temperature at 50 and 500 metres Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 2GB

REF2_cont [2GB] REF2_cont [2GB] REF2_cont [2GB] Security: Anyone File name: REF2_cont.zip Content type: Data Description: Folder with ONDJF sea surface salinity (oceansalipf), ocean salinity at 500 and 50 metres depth. Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 2GB

REF2_cont2 [1GB] REF2_cont2 [1GB] REF2_cont2 [1GB] Security: Anyone File name: REF2_cont2.zip Content type: Data Description: Folder with annual and winter mixed layer depth, annual surface air temperature, March meridional surface ocean velocity (oceanvvel). Mime-Type: application/zip License: Creative Commons Attribution 4.0 International (CC BY 4.0) File size: 1GB

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