Multi-model ensembles (MME) are commonplace in Earth system modeling. Here we perform MME integration using a 10-member ensemble of terrestrial biosphere models (TBMs) from the Multi-scale synthesis and Terrestrial Model Intercomparison Project (MsTMIP). We contrast optimal (skill-based for present-day carbon cycling) versus naïve (“one model – one vote”) integration. MsTMIP optimal and naïve mean land sink strength estimates (–1.16 vs. –1.15 Pg C per annum respectively) are statistically indistinguishable. This holds also for grid cell values and extends to gross uptake, biomass, and net ecosystem productivity. TBM skill is similarly indistinguishable. The added complexity of skill-based integration does not materially change MME values. This suggests that carbon metabolism has predictability limits and/or that all models and references are misspecified. Resolving this issue requires addressing specific uncertainty types (initial conditions, structure, references) and a change in model development paradigms currently dominant in the TBM community.
Schwalm, Christopher R., et al. "Toward “optimal” integration of terrestrial biosphere models." Geophysical Research Letters, vol. 42, no. 11, Jun. 2015. https://doi.org/10.1002/2015GL064002
Schwalm, Christopher R., Huntingzger, Deborah, Fisher, Joshua B., Michalak, A. M., Bowman, Kevin, Cias, Philippe, Cook, Robert B., El-Masri, Bassil, Hayes, Daniel J., Huang, Maoyi, Ito, A., Jain, Atul K., King, Anthony W., Lei, Huimin, Liu, Junjie, Lu, Chaoqun, Mao, Jiafu, Peng, Shushi, ... Zeng, Ning (2015). Toward “optimal” integration of terrestrial biosphere models. Geophysical Research Letters, 42(11). https://doi.org/10.1002/2015GL064002
Schwalm, Christopher R., Huntingzger, Deborah, Fisher, Joshua B., et al., "Toward “optimal” integration of terrestrial biosphere models," Geophysical Research Letters 42, no. 11 (2015), https://doi.org/10.1002/2015GL064002
@article{osti_1221484,
author = {Schwalm, Christopher R. and Huntingzger, Deborah and Fisher, Joshua B. and Michalak, A. M. and Bowman, Kevin and Cias, Philippe and Cook, Robert B. and El-Masri, Bassil and Hayes, Daniel J. and Huang, Maoyi and others},
title = {Toward “optimal” integration of terrestrial biosphere models},
annote = {Multi-model ensembles (MME) are commonplace in Earth system modeling. Here we perform MME integration using a 10-member ensemble of terrestrial biosphere models (TBMs) from the Multi-scale synthesis and Terrestrial Model Intercomparison Project (MsTMIP). We contrast optimal (skill-based for present-day carbon cycling) versus naïve (“one model – one vote”) integration. MsTMIP optimal and naïve mean land sink strength estimates (–1.16 vs. –1.15 Pg C per annum respectively) are statistically indistinguishable. This holds also for grid cell values and extends to gross uptake, biomass, and net ecosystem productivity. TBM skill is similarly indistinguishable. The added complexity of skill-based integration does not materially change MME values. This suggests that carbon metabolism has predictability limits and/or that all models and references are misspecified. Resolving this issue requires addressing specific uncertainty types (initial conditions, structure, references) and a change in model development paradigms currently dominant in the TBM community.},
doi = {10.1002/2015GL064002},
url = {https://www.osti.gov/biblio/1221484},
journal = {Geophysical Research Letters},
issn = {ISSN 0094-8276},
number = {11},
volume = {42},
place = {United States},
publisher = {American Geophysical Union},
year = {2015},
month = {06}}
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