Spontaneous Dansgaard-Oeschger type oscillations in climate models

Start date
1 January, 2020
End date
1 August, 2021

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 190-217 ppm (Klockmann et al., 2018, 2020) (See figure below). 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). Authors term this behaviour as a “kicked” salt oscillator.



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 SDOO is currently gathering model output for any spontaneously oscillating simulations (published or unpublished).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.


ModelTime period of the simulationLengthAtmospheric trace gasesInsolationIce sheets
MPI-ESMMixed forcing12000CO2 = 206ppm
CH4 = 444ppb
N2O = 218ppb
Mixed forcing8000CO2 = 206ppm
CH4 = 444ppb
N2O = 218ppb
Mixed forcing8000CO2 = 195ppm
CH4 = 396ppb
N2O = 209ppb
GISS E2-R (TCADI)Future warming scenario2500CO2 = 4 x PI CO2modernmodern
Future warming scenario2500CO2 = CO2 increases at 1%/year until 4x CO2 and then held constantmodernmodern
Future warming scenario4300RCP85 emissionsmodernmodern
GISS E2.1-G (NINT)Future warming scenario650SSP45 emissionsmodernmodern
EC-Earth3-Veg-LRHolocene transient from 8K4000 (8ka-4ka)Köhler et al (2017)Berger (1978)PI
LIG transient from 127K3000 (127ka – 124ka)Köhler et al (2017)Berger (1978)PI
UVIC 2.819 ka10000CO2 = 190ppm19 ka19 ka – ICE 4G
UofT CCSM4LGM500021 ka21 ka21 ka – ICE 6G (VM5a)
CLIMBER-3αDevoninian (415 Ma & 380 Ma)5000CO2 = 1500ppm, a few runs with 500ppm, 800ppm, 2000ppmVarious obliquity values, eccentricities, precession anglesnone
Mesozoic (240-145 Ma)5000CO2 = 500-1700 ppm depending on time slicecircular orbit, obliquity 23.5 °none
PlaSim v16 TransientDeglaciation transient (21ka – 6ka)15000Transiently changing following PMIP4Transienttransient following GLAC1-D
PLaSim v17-SEDGES38ka1000CO2 = 185ppm
CH4 = 405ppb
N2O = 207.5ppb
38ka38ka – GLAC1-D

SDOO is organized by:

and has contributions from Marlene Klockmann (MPI-ESM), Gavin A. Schmidt (GISS E2-R and GISS E2.1-G), Qiong Zhang (EC-Earth3-Veg-LR), Olivier Arzel (UVIC 2.8), Dick Peltier and Guido Vettoretti (UofT CCSM4), Georg Feulner (CLIMBER-3α), Andres Heather (PlaSim v16 and PlaSim v17-SEDGES) and Yvan Rome (HadCM3).