Experiment title 
: TRENDY-GCB2026
Summary : This proposal is to use the CABLE-POP model to contribute to this year’s TRENDY-MIP, which is part of the annual carbon budget assessment (GCB) of the Global Carbon Project. The whole setup as well as the results will be available for the CABLE and ACCESS communities.
Scientific motivation: The model simulations will form part of an ensemble of DGVMs and TBMs that are used to assess the magnitude of the terrestrial carbon sink and its response to changes in climate, CO2 and land use.
Experiment Name : TRENDY-GCB2026
People : Juergen Knauer, Ian Harman
Model: CABLE-POP
Configuration: branch CABLE-POP_TRENDY on github
Initial conditions: The model will use CRU-JRA(3Q) climate data, LUH2 data on land use change. The model will make use of its standard spinup process, starting at zero biomass.
Run plan: The experiment consists of 7 factorial runs. Runs comprise a spinup period and main simulations from 1700 - 2025, all run globally at 1degree resolution.
Simulation details: See Run plan. This year, three additional simulations will be run: 1) LUC only (fixed climate and CO2), 2) LUC and CO2 with fixed climate, 3) Climate and LUC with fixed CO2.
Total KSUs required : 60 kSUs
Total storage required : 12TB for 2026.q3
Outputs: 12TB (only needed for Q3/2026) on /g/data/rp23/experiments. Final results can be stored/archived in other locations, which will need to be discussed. In total, ~70 variables will be delivered.
Restarts: A series of restart files during and after spinup will be produced.
Related articles:
Sitch, S. et al. Trends and Drivers of Terrestrial Sources and Sinks of Carbon Dioxide: An Overview of the TRENDY Project. Global Biogeochemical Cycles 38, e2024GB008102 (2024).
Friedlingstein, P. et al. Global Carbon Budget 2025, Earth Syst. Sci. Data, 18, 3211–3288 (2026).
Analysis:
Outputs from previous years are freely available here: Global Carbon Budget Data Browser
Model evaluation results are available here: ILAMB Analysis for TRENDYv13
Conclusion:
The TRENDY project is part of the annual global carbon assessment effort, which is published in Earth System Science Data or a similar journal end of this year. Results will also be freely available to the community and can be used for model benchmarking and follow-up scientific analyses.
The CABLE-POP model has consistently shown above-average performance among the participating models (see Figure S11 in Friedlingstein et al. 2026).
