Responsible activity: CMIP

1% per year increase in atmospheric carbon dioxide levels. All other conditions are kept the same as piControl.

Experiment set up¶

The 1pctCO2 simulation is a simple branch from the piControl simulation. After branching, the atmospheric CO₂ concentrations should increase at one percent per year throughout the simulation.

The start-time of the simulation is not tied to a particular year but, rather, can be chosen arbitrarily (e.g., year 200 or year 1850 or year 1). However, it is easier for analysts if the start-time is consistent with the branching time in the parent experiment (e.g., if the the simulation branches from year 200 in the parent experiment, then the start time in the child experiment would be set to year 200). Simulations should be at least 150 years in length. Only one ensemble member is required.

Parent experiment¶

1pctCO2 branches from the piControl simulation (part of CMIP).

Branch from piControl at a time of your choosing.

Forcings¶

General headlines¶

The 1pctCO2 experiment is a fixed forcings experiment, except for CO₂ which is transient.

Notes¶

See notes for the piControl simulation.

Versions to use¶

The forcings relevant for this simulation are the same as for the piControl simulation.

Getting the data¶

See instructions for the piControl simulation. You have to increase the atmospheric CO₂ concentrations at one percent per year yourself.

The annual-average concentrations should increase following the formula c(y) = c_0 * 1.01 ** (y - y_0 - 1), where c is the annual-average concentration in year y and y_0 is the first year of the 1pctCO2 simulation (i.e. average atmospheric CO₂ concentrations in the first year of the 1pctCO2 simulation should be higher than in piControl). It is up to you to decide whether you apply your concentrations as a series of step changes (constant over each year) or as a steady linear increase (such that e.g. concentrations in December are higher than those in January) that results in the correct annual average being applied.