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The SSP scenario experiments can be understood in terms of two pathways, a Shared Socioeconomic Pathway (SSP) and a Representative Concentration Pathway (RCP). The two pathways are represented by the three digits that make up the experiment’s name. The first digit represents the SSP storyline for the socio-economic mitigation and adaptation challenges that the experiment represents (Figure 1). The second and third digits represent the RCP climate forcing that the experiment follows. For example, experiment ssp245 follows SSP2, a storyline with intermediate mitigation and adaptation challenges, and RCP4.5 which leads to a radiative forcing of 4.5 Wm-2 by the year 2100.
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Figure 1 - The socioeconomic “Challenge Space” to be spanned by the CMIP6 SSP experiments (O’Neil et al. 2014).
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| title | Click here to expand... CMIP6 experiments included in the CDS |
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Experiment name | Extended Description | historical | The historical experiment is a simulation of the recent past from 1850 to 2014, it is performed with a coupled atmosphere-ocean general circulation model (AOGCM). In the historical simulations the model is forced with changing conditions (consistent with observations) which include atmospheric composition, land use and solar forcing. The initial conditions for the historical simulation are taken from the pre-industrial control simulation (piControl) at a point where the remaining length of the piControl is sufficient to extend beyond the period of the historical simulation to the end of any future "scenario" simulations run by the same model. The historical simulation is used to evaluate model performance against present climate and observed climate change. | SSP5-8.5 | SSP5-8.5 | ssp585 | ssp585 is a scenario experiment extending into the near future from 2015 to 2100, it is performed with a coupled atmosphere-ocean general circulation model (AOGCM). The forcing for the CMIP6 SSP experiments is derived from shared socioeconomic pathways (SSPs), a set of emission scenarios driven by different socioeconomic assumptions, paired with representative concentration pathways (RCPs), global forcing pathways which lead to specific end of century radiative forcing targets. SSP5-8. ssp585 5 is based on SSP5 in which climate change mitigation challenges dominate and RCP8.5, a future pathway with a radiative forcing of 8.5 W/m2 in the year 2100. The ssp585 scenario represents the high end of plausible future forcing pathways. ssp585 SSP5-8.5 is comparable to the CMIP5 experiment RCP8.5. | SSP3-7.0 | SSP3-7.0 | ssp370 | ssp370 is a scenario experiment extending into the near future from 2015 to 2100, it is performed with a coupled atmosphere-ocean general circulation model (AOGCM). The forcing for the CMIP6 SSP experiments is derived from shared socioeconomic pathways (SSPs), a set of emission scenarios driven by different socioeconomic assumptions, paired with representative concentration pathways (RCPs), global forcing pathways which lead to specific end of century radiative forcing targets. SSP3-7. ssp370 0 is based on SSP3 in which climate change mitigation and adaptation challenges are high and RCP7.0, a future pathway with a radiative forcing of 7.0 W/m2 in the year 2100. The ssp370 SSP3-7.0 scenario represents the medium to high end of plausible future forcing pathways. SSP3-7. ssp370 0 fills a gap in the CMIP5 forcing pathways that is particularly important because it represents a forcing level common to several (unmitigated) SSP baseline pathways. | SSP2-4.5 | SSP2-4.5 | ssp245 | ssp245 is a scenario experiment extending into the near future from 2015 to 2100, it is performed with a coupled atmosphere-ocean general circulation model (AOGCM). The forcing for the CMIP6 SSP experiments is derived from shared socioeconomic pathways (SSPs), a set of emission scenarios driven by different socioeconomic assumptions, paired with representative concentration pathways (RCPs), global forcing pathways which lead to specific end of century radiative forcing targets. SSP2-4. ssp245 5 is based on SSP2 with intermediate climate change mitigation and adaptation challenges and RCP4.5, a future pathway with a radiative forcing of 4.5 W/m2 in the year 2100. The ssp245 scenario represents the medium part of plausible future forcing pathways. SSP2-4. ssp245 5 is comparable to the CMIP5 experiment RCP4.5. | SSP1-2.6 | SSP1-2.6 | ssp126 | ssp126 is a scenario experiment extending into the near future from 2015 to 2100, it is performed with a coupled atmosphere-ocean general circulation model (AOGCM). The forcing for the CMIP6 SSP experiments is derived from shared socioeconomic pathways (SSPs), a set of emission scenarios driven by different socioeconomic assumptions, paired with representative concentration pathways (RCPs), global forcing pathways which lead to specific end of century radiative forcing targets. SSP1-2. ssp126 6 is based on SSP1 with low climate change mitigation and adaptation challenges and RCP2.6, a future pathway with a radiative forcing of 2.6 W/m2 in the year 2100. The ssp126 SSP1-2.6 scenario represents the low end of plausible future forcing pathways. SSP1-2. ssp126 6 depicts a "best case" future from a sustainability perspective. | SSP4-6.0 | SSP4-6.0 | ssp460 | ssp460 is a scenario experiment extending into the near future from 2015 to 2100, it is performed with a coupled atmosphere-ocean general circulation model (AOGCM). The forcing for the CMIP6 SSP experiments is derived from shared socioeconomic pathways (SSPs), a set of emission scenarios driven by different socioeconomic assumptions, paired with representative concentration pathways (RCPs), global forcing pathways which lead to specific end of century radiative forcing targets. SSP4-6. ssp460 0 is based on SSP4 in which climate change adaptation challenges dominate and RCP6.0, a future pathway with a radiative forcing of 6.0 W/m2 in the year 2100. The ssp460 SSP4-6.0 scenario fills in the range of medium plausible future forcing pathways. ssp370 SSP4-6.0 defines the low end of the forcing range for unmitigated SSP baseline scenarios. | SSP4-3.4 | SSP4-3.4 | ssp434 | ssp434 is a scenario experiment extending into the near future from 2015 to 2100, it is performed with a coupled atmosphere-ocean general circulation model (AOGCM). The forcing for the CMIP6 SSP experiments is derived from shared socioeconomic pathways (SSPs), a set of emission scenarios driven by different socioeconomic assumptions, paired with representative concentration pathways (RCPs), global forcing pathways which lead to specific end of century radiative forcing targets. SSP4-3. ssp434 4 is based on SSP4 in which climate change adaptation challenges dominate and RCP3.4, a future pathway with a radiative forcing of 3.4 W/m2 in the year 2100. The ssp434 SSP4-3.4 scenario fills a gap at the low end of the range of plausible future forcing pathways. SSP4-3.ssp370 4 is of interest to mitigation policy since mitigation costs differ substantially between forcing levels of 4.5 W/m2 and 2.6 W/m2. | ssp534SSP5-over3.4OS | ssp534SSP5-over 3.4OS is a scenario experiment with simulations beginning in the mid-21st century running from 2040 to 2100, it is performed with a coupled atmosphere-ocean general circulation model (AOGCM). The forcing for the CMIP6 SSP experiments is derived from shared socioeconomic pathways (SSPs), a set of emission scenarios driven by different socioeconomic assumptions, paired with representative concentration pathways (RCPs), global forcing pathways which lead to specific end of century radiative forcing targets. ssp534SSP5-over 3.4OS is based on SSP5 in which climate change mitigation challenges dominate and RCP3.4-over, a future pathway with a peak and decline in forcing towards an eventual radiative forcing of 3.4 W/m2 in the year 2100. The ssp534SSP5-over 3.4OS scenario branches from ssp585 SSP5-8.5 in the year 2040 whereupon it applies substantially negative net emissions. ssp534SSP5-over 3.4OS explores the climate science and policy implications of a peak and decline in forcing during the 21st century. SSP5-3. ssp534 4OS fills a gap in existing climate simulations by investigating the implications of a substantial overshoot in radiative forcing relative to a longer-term target. | SSP1-1.9 | SSP1-1.9 | ssp119 | ssp119 is a scenario experiment extending into the near future from 2015 to 2100, it is performed with a coupled atmosphere-ocean general circulation model (AOGCM). The forcing for the CMIP6 SSP experiments is derived from shared socioeconomic pathways (SSPs), a set of emission scenarios driven by different socioeconomic assumptions, paired with representative concentration pathways (RCPs), global forcing pathways which lead to specific end of century radiative forcing targets. SSP1-1. ssp119 9 is based on SSP1 with low climate change mitigation and adaptation challenges and RCP1.9, a future pathway with a radiative forcing of 1.9 W/m2 in the year 2100. The ssp119 SSP1-1.9 scenario fills a gap at the very low end of the range of plausible future forcing pathways. SSP1-1. ssp119 9 forcing will be substantially below ssp126 SSP1-2.6 in 2100. There is policy interest in low-forcing scenarios that would inform a possible goal of limiting global mean warming to 1.5°C above pre-industrial levels based on the Paris COP21 agreement. |
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Frequency | Number of Levels | Pressure Levels (hPa) |
Daily | 8 | 1000., 850., 700., 500., 250., 100., 50., 10. |
Monthly | 19 | 1000., 925., 850., 700., 600., 500., 400., 300., 250., 200., 150., 100., 70., 50., 30., 20., 10., 5., 1. |
Ensembles
Each modelling centre typically run the same experiment using the same model with slightly different settings several times to confirm the robustness of results and inform sensitivity studies through the generation of statistical information. A model and its collection of runs is referred to as an ensemble. Within these ensembles, four different categories of sensitivity studies are done, and the resulting individual model runs are labelled by four integers indexing the experiments in each category
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CDS parameter name for CMIP5 | Variable ESGF variable id | Long name to be used in CMIP6 | Units | 2m temperature | tas | Near-Surface Air Temperature | KelvinKelvin | Maximum 2m temperature in the last 24 hours | tasmax | Daily Maximum Near-Surface Air Temperature | KelvinKelvin | Minimum 2m temperature in the last 24 hours | tasmin | Daily Minimum Near-Surface Air Temperature | Kelvin | Kelvin | | Maximum 10m wind speed in the last 24 hours | sfcwindmax | Daily Maximum Near-Surface Wind Speed | m s-1 | | Skin temperature | ts | Surface Temperature | Kelvin | | Mean sea level pressure | psl | Sea Level Pressure | Pa | | Surface pressure | ps | Surface Air Pressure | Pa | | 10m u component of wind | uas | Eastward Near-Surface Windm | m s-1 | | 10m v component of wind | vas | Northward Near-Surface Windm | m s-1 | | 10m wind speed | sfcWind | Near-Surface Wind Speedm | m s-1 | | 2m relative humidity | hurs | Near-Surface Relative Humidity | 1 | | 2m specific humidity | huss | Near-Surface Specific Humidity | 1 | | Mean precipitation flux | pr | Precipitation | kg m-2s-1 | | Snowfall | prsn | Snowfall Flux | kg m- | 2 2 s-1 | | Evaporation | evspsbl | Evaporation Including Sublimation and Transpiration | kg m- | 2 2 s-1 | | Atmosphere water vapor content | prw | Atmosphere Water Vapor Content | kg m-2 | | Eastward turbulent surface stress | tauu | Surface Downward Eastward Wind Stress | Pa | | Northward turbulent surface stress | tauv | Surface Downward Northward Wind Stress | Pa | | Surface latent heat flux | hfls | Surface Upward Latent Heat Flux | W m-2 | | Surface sensible heat flux | hfss | Surface Upward Sensible Heat Flux | W m- | 2 2 | | Surface thermal radiation downwards | rlds | Surface Downwelling Longwave Radiation | W m-2 | Surface upwelling longwave radiation | rlus | Surface Upwelling Longwave Radiation | W m-2 | Surface solar radiation downwards | rsds | Surface Downwelling Shortwave Radiation | W m-2 | Surface upwelling shortwave radiation | rsus | Surface Upwelling Shortwave RadiationRadiation | W m-2 | TOA incident solar radiation | rsdt | TOA Incident Shortwave Radiation | W m-2 | | TOA outgoing shortwave radiation | rsut | TOA Outgoing Shortwave Radiation | W m-2 | | TOA outgoing longwave radiation | rlut | TOA Outgoing Longwave Radiation | W m-2 | | TOA outgoing clear-sky shortwave radiation | rsutcs | TOA Outgoing Shortwave Flux Assuming Clear Sky | W m-2 | | TOA outgoing clear-sky longwave radiation | rlutcs | TOA Outgoing Longwave Flux Assuming Clear Sky | W m-2 | | Total cloud cover | clt | Total Cloud Cover Percentage | 1 | | Air temperature | ta | Air Temperature | K | | U-component of wind | ua | Eastward Windm | m s-1 | | V-component of wind | va | Northward Windm | m s-1 | | Relative humidity | hur | Relative Humidity | 1 | | Specific humidity | hus | Specific Humidity | 1 | | Geopotential height | zg | Geopotential Height | m | | Surface snow amount | snw | Surface Snow Amountkg m | kg m-2 | | Snow depth | snd | Snow Depth | m | | Surface runoff | mrros | Surface Runoff Flux | kg m-2 s-1 | | Runoff | mrro | Total Runoff | kg m- | 2 2 s-1 | | Soil moisture content | mrsos | Moisture in Upper Portion of Soil Column | kg m-2 | | Sea-ice area percentage | siconc | Sea-Ice Area Percentage (Ocean Grid) | 1 | | Sea ice thickness | sithick | Sea Ice Thickness | m | | Sea ice plus snow amount | simass | Sea-Ice Mass per Area | kg m-2 | | Sea ice surface temperature | sitemptop | Surface Temperature of Sea Ice | K | | Sea surface temperature | tos | Sea Surface Temperature | K | | Sea surface salinity | sos | Sea Surface Salinity1e-3 | PSU | | Sea surface height above geoid | zos | Sea Surface Height Above Geoid | m | | Grid-cell area for ocean variables | areacello | Grid-Cell Area for Ocean Variables*m2 | m2 | | Sea area percentage | sftof | Sea Area Percentage* | % | | Grid-cell area for atmospheric grid variables | areacella | Grid-Cell Area for Atmospheric Grid Variables*m2 | m2 | | Capacity of soil to store water (field capacity) | mrsofc | Capacity of Soil to Store Water (Field Capacity)* | kg m-2 | | Percentage of grid cell occupied by land (including lakes) | sftlf | Percentage of the Grid Cell Occupied by Land (Including Lakes)* | % | | Land ice area percentage | sftgif | Land Ice Area Percentage* | 1 | | Orography | orog | Surface Altitude* | m |
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Data Format
The CDS subset of CMIP6 data are provided as NetCDF files. NetCDF (Network Common Data Form) is a file format that is freely available and commonly used in the climate modelling community. See more details: What are NetCDF files and how can I read them
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