OSCAR abrupt postfire repository

This repository contains the script and input files used to run OSCAR v3.0, a compact Earth System Model, for the analyses presented in

Schädel, C., Gasser, T., Rogers, B.M., Treharne, R., Turetsky, M.R., Smith, T., MacDonald, E., and Natali, S.M. (2026). Permafrost and wildfire carbon emissions indicate need for additional action to keep Paris Agreement temperature goals within reach. Commun. Earth Environ. https://doi.org/10.1038/s43247-026-03189-5

OSCAR is maintained at: https://github.com/tgasser/OSCAR The OSCAR framework is documented in Gasser et al. (2017, 2018).

Model extensions

This version extends OSCAR v3.0 to simulate:

• abrupt permafrost thaw,
• below-ground carbon combustion from high-latitude fires
• post-fire permafrost thaw emissions

Repository structure

core_fct/

Core OSCAR model code. New permafrost and fire modules are implemented in fct_process.py (Section 1.4: Permafrost)

input_data/ Model input files

• drivers/: historical and scenario forcing files
• parameters/: parameter files defining specific model configurations

run_scripts/

Example run script used to generate the simulations in the manuscript.

results/

Processed .csv files containing the model output data used to generate the figures in the manuscript and supplement. These files include final aggregated values (means and uncertainties where applicable) used directly for plotting.

Full raw OSCAR model outputs and intermediate Monte Carlo files are not included due to their volume and complexity.

Parameter files

Parameter files follow the pattern:

Pars_500.nc

where:

• <model> is the land surface model used to calibrate the gradual thaw emulator (e.g. JSBACH, JULES_DR, ORCHIDEE)
• 500 denotes the number of Monte-Carlo parameter configurations
• <sim> denotes the permafrost configuration:
  • a: gradual thaw only
  • b: gradual + abrupt thaw
  • c: gradual + abrupt thaw + combustion
  • d: gradual + abrupt thaw + combustion + post-fire thaw

References

1. Gasser et al. (2017). The compact Earth system model OSCAR v2.2: description and first results.
   https://doi.org/10.1038/ngeo3031

2. Gasser et al. (2018). Path-dependent reductions in CO2 emission budgets caused by permafrost carbon release.
   https://doi.org/10.1038/s41561-018-0227-0