This repository contains climate simulation output from simulations run at 0.9x1.25° spatial resolution on the Community Earth System Model version 2 (CESM2; Danabasoglu et al., 2020), which is comprised of the Community Land Model 5 (CLM5; Lawrence et al., 2019), the Community Atmosphere Model 6 (CAM6; Bogenschutz et al., 2018), and a slab ocean based on output from the CESM2 Coupled Model Intercomparison Project Phase 6 (CMIP6; Danabasoglu & Gent, 2009) preindustrial control run.

Description of the data and file structure

This dataset is organized into zipped tarbells of the monthly timeseries output for our simulations. Each simulation has a *_lnd.tar for the land output and a *_atm.tar for the atmosphere output. Within each tarball, there is one netCDF file for each variable. Details about the simulations and variables are described further below.

SimulationA.tar.gz
|- VariableA.nc
|- VariableB.nc
SimulationB.tar.gz
|- VariableA.nc
|- VariableB.nc

Climate model simulation output

We present data from thirteen simulations run for 120 years at four different model configurations:

• coupled_*_SP_* (Dynamic atmosphere and prescribed leaf area; Note that SP is at the end of the file name here)
• coupled_* (Dynamic atmosphere and prognostic leaf area)
• landonly_SP_* (Prescribed atmosphere and prescribed leaf area; Note that SP follows right after landonly here)
• landonly_* (Prescribed atmosphere and prognostic leaf area)

Configurations either had a dynamic or prescribed atmosphere and a prognostic (active biogeochemistry) or prescribed leaf area. Prescribed atmosphere and prescribed leaf area forcings were based on the output of the dynamic atmosphere and prognostic leaf area with default Medlyn slope parameter simulations.

There are two fixed atmospheric CO₂ concentrations for the dynamic atmosphere simulations:

• 1xCO2 (1x preindustrial CO₂ concentration; 284.7ppm)
• 2xCO2 (2x preindustrial CO₂ concentration; 569.4ppm)

The prescribed atmosphere simulations were also run at both 1x and 2x preindustrial CO₂, but in a slightly different naming convention:

• 1xCO2CPL_1xCO2 (1x preindustrial CO₂ concentration; 284.7ppm)
• 2xCO2CPL_1xCO2 (2x preindustrial CO₂ concentration; 569.4ppm)

There are three Medlyn slope parameter values:

• DEFmedslope (default Medlyn slope used in CLM5)
• LOWmedslope (5th percentile Medlyn slope based on Lin et al. 2015 dataset)
• HIGHmedslope (95th percentile Medlyn slope based on Lin et al. 2015 dataset)

We perturbed the Medlyn slope parameter by setting a minimum and maximum for each plant functional type based on the 5th and 95th percentile from Lin et al. (2015). In our analysis we compared the high and low Medlyn slope simulations against simulations with the default Medlyn slope parameter values used in CLM5. The default Medlyn slope values do not represent the mean or median of the observations we used for perturbations.

Simulations with a dynamic atmosphere are named according to the convention coupled_MedlynSlopeValue_atmCO2_LAI_Number and simulations without a dynamic atmosphere are named according to the convention landonly_LAI_MedlynSlopeValue_1xCO2CPL_1xCO2_Version. Some dynamic atmosphere simulations are comprised of two simulations and denoted by the Number which, which will follow chronological order (e.g., *_03 is the first half and *_05 is the second half of * simulation).

Variables 

Each variable's netCDF file is named using an abbreviation. Abbreviated variable names can be mapped to full variable names in var_key.csv. The table below lists the variables analyzed in the Liu et al. (2025) manuscript that references this dataset, along with their abbreviation and units. Note that this table is a subset of the full list of variables. For a crosswalk between abbreviations and variable names for all other outputs, please reference the CESM output variable directory. Additional metadata about the variables are contained in the netCDF files. 

Code/Software

The Community Earth System Model version 2 (CESM2) is open source and all code can be found on Github at https://github.com/ESCOMP/CESM. We thank all scientists, software engineers, and administration who contributed to CESM2's development.