Spontaneous Dansgaard-Oeschger type Oscillations in climate models (SDOO)

Start date
1 January, 2020
End date
31 December, 2024

Abrupt warming episodes punctuate Greenland ice core records throughout the last glacial period. These events were first identified in two Greenland stable water isotope records (Dansgaard et al., 1993), and are generally referred to as Dansgaard-Oeschger (DO) events. During an event, Greenland transitions from cold stadial (GS) to warmer Greenland Interstadial (GI) conditions within a decade (Kindler et al., 2014; Huber et al., 2006). Surface air temperatures (SATs) over Greenland increase by 10-15°C and local snow accumulation almost doubles (Andersen et al., 2006; Kindler et al., 2014; Huber et al., 2006). These events occur at the onset of an oscillation that is of millennial timescale and are rather pronounced during Marine Isotope Stage3 (MIS3; between approximately 25 – 60 thousand of years BP, hereafter ka) (Fig. 1; Johnsen et al. (2001), Voelker et al.(2002)).

There are currently few examples of spontaneous DO-type oscillations occurring in coupled climate models, under any climate conditions, glacial-state or otherwise. For example the Max-Planck Institute Earth System Model (MPI-ESM) model is able to reproduce spontaneous millennial-scale AMOC oscillations when implementing PI ice sheet distribution in combination with a CO2 concentration range of 195-217 ppm (Klockmann et al., 2018, 2020) (See Figure 1). Under full glacial conditions, Peltier and Vettoretti (2014) found regular cycles of DO-type oscillations with the University of Toronto version of CCSM4 (UofT CCSM4) (See Figure 1). Authors term this behaviour as a “kicked” salt oscillator. Under late glacial conditions, at 30 ka, a quasi-oscillating AMOC is produced by the HadCM3 model (Armstrong et al., 2021) and results from a North Atlantic salt oscillator mechanism similar to that in UofT CCSM4 (Peltier and Vettoretti, 2014; Vettoretti and Peltier, 2016; Peltier et al., 2020) (See Figure 1).


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Figure 1. MIS3 temperature reconstruction from North Greenland Ice Core Project (NGRIP) based on δ18O and  δ15N records (NGRIP Project Members, 2004; Kindler et al., 2014). Also shown, stack of anomalous (relative to the past millennium) Antarctic Temperature based on δD and δ18O records from six ice cores: EPICA Dronning Maud Land(EDML), EPICA Dome C, Talos Dome, Vostok, WAIS Divide Core and Dome Fuji as published in (Pedro et al., 2018). (b-d) MPI-ESM, (e-h) HadCM3 and (i-l) CCSM4 time series of modelled surface air temperature in Greenland and Antarctica at the grid points closest to the NGRIP (blue) and WDC (red) ice core sites, respectively. Modelled data is in timeseries of decadal average and smoothed with a 100-year running mean.



SDOO is an ongoing model intercomparison project to study spontaneous, DO-type oscillations in climate models. SDOO is currently gathering model output for any spontaneously oscillating simulations (published or unpublished). The main goal of SDOO is to cross compare existing simulations using a common set of diagnostics so we can analyse the mechanisms and the characteristics of the oscillations.

The only condition to participate is a simulation that shows spontaneous, long time scale, oscillations. The table below shows the simulations and models currently involved in this initiative.


Model Time period of the simulation Run Length Atmospheric trace gases Insolation Ice sheets
MPI-ESM Mixed forcing +12000 CO2 = 206ppm

CH4 = 444ppb

N2O = 218ppb

21ka PI
8000 CO2 = 206ppm

CH4 = 444ppb

N2O = 218ppb

8000 CO2 = 195ppm

CH4 = 396ppb

N2O = 209ppb

CCSM4 LGM 8000 – 10000 CO2 range between 185 and 230 ppm 21 ka 21ka – ICE-6G (VM5a)
HadCM3 MIS3 30 ka 4700 – 10000 CO2 range between 190 and 220 ppm 30 ka 30 ka
5000 – 10000 30 ka Orbital configurations between 26 – 34 ka 30 ka
5000 – 10000 30 ka 30 ka Varying 30 ka Laurentide Ice Sheet configurations
UVIC 2.8 19 ka 10000 CO2 = 190ppm 19 ka 19 ka – ICE 4G
CLIMBER-3α Devoninian (415 Ma & 380 Ma) 5000 CO2 = 1500ppm, a few runs with 500ppm, 800ppm, 2000ppm Various obliquity values, eccentricities, precession angles none
Mesozoic (240-145 Ma) 5000 CO2 = 500-1700 ppm depending on time slice circular orbit, obliquity 23.5° none

Data already uploaded to JASMIN ( and available for analysis.

SDOO is organized by:

and has contributions from Marlene Klockmann (MPI-ESM), Qiong Zhang (EC-Earth3-Veg-LR), Olivier Arzel (UVIC 2.8), Dick Peltier and Guido Vettoretti (UofT CCSM4), Georg Feulner (CLIMBER-3α), John Slaterry and Yvan Rome (HadCM3).

This project is TiPES contribution #123: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 820970.