PCMIP Experiments

Millenium diagnostic Carbon Dioxide (PMIP/PCMIP)

• Goals: (1) To diagnose carbon partitioning between land and ocean on centennial time scales and (2) to use the Medieval Warm Period/LIA as a constraint on carbon-climate sensitivity
• Experiment: Simulations from 850 AD to 1850 AD will be run using prescribed CO₂. Other forcings (orbital, solar, volcanic, GHGs, land-use, fossil fuel emissions) will also be prescribed. The implied carbon fluxes will be calculated and used to calculate a "diagnostic" CO₂ which however will not influence the simulated climate. This is the PMIP Millennium experiments as run by those modelling groups with an explicit carbon cycle, and is a Tier 2 experiment in CMIP5. PCMIP will be responsible for the carbon-cycle analyses of these simulations (Experimental protocols)
• Model evaluation: Comparison of "diagnostic" CO₂ with the ice-core CO₂ and use of the ¹³CO₂ records for constraints on land/ocean partitioning. PCMIP will seek to use high resolution records of fire, vegetation productivity and ocean parameters (Datasets)
• Simulations could be extended up to 2005 (or 2100, for one RCP scenario)

Millennium prognostic Carbon Dioxide (PCMIP)

• Goals: (1) to improve earth system models and (2) understand the controls on CO₂ on decadal to centennial timescales
• Experiment: Prognostic carbon-cycle simulations will be run from 850 AD to 1850 AD. Other forcings (orbital, solar, volcanic, other GHGs, land-use, fossil fuel emissions) will be prescribed
• Model evaluation: Comparison of simulated CO₂ with the ice-core CO₂ and use of the ¹³CO₂ records for constraints on land/ocean partitioning. PCMIP will seek to use high resolution records of fire, vegetation productivity and ocean parameters (Datasets)
• Simulations could be extended up to 2005 (or 2100, for one RCP scenario)

LGM diagnostic Carbon Dioxide (PCMIP)

• Goals: (1) to diagnose whether current earth-system models can produce the observed lowering of CO₂ at the LGM, (2) to evaluate the relative importance of different mechanisms in explaining the observed CO₂ drawdown
• Experiment: Snapshot simulations of the Last Glacial Maximum (21ka) will be run using prescribed glacial CO₂. Other forcings (orbital, other GHGs, land-sea geography, ice sheets, atmospheric dust loading) will also be prescribed following the PMIP protocols. Vegetation will be prescribed in those earth-system models without fully dynamic vegetation. The equilibrium land and ocean carbon pools will be used to calculate a "diagnostic" LGM CO₂
• Model evaluation: Comparison of "diagnostic" CO₂ with the ice-core CO₂ and use of the ¹³CO₂ records for constraints on land/ocean partitioning. PCMIP will use benchmark data sets being produced or updated by the MARGO, MARGO DEEP, and BIOME 6000 groups. PCMIP will seek to use improved data sets of marine production/export, vegetation cover, and terrestrial ¹³C. It would also be useful to develop an inventory of peat extent and volume at 21ka (Datasets)

Experimental Protocols

Full experimental protocols for the PCMIP experiments will be posted here by August 2009.