Control of global temperature in concentration-driven climate models (June 2026)
Description
We present two methods to generate time-varying carbon dioxide (CO2) concentrations in order to drive an atmosphere-ocean general circulation model (AOGCM) to a desired target timeseries of global mean surface temperature. Specifically, we consider targets of a linear rampup rate of surface temperature, stabilisation at a given target temperature, and ramp down at a fixed rate after a period of stabilisation, as proposed for standard experiments of the Tipping Point Model Intercomparison Project (TIPMIP). The first method method pre-calculates the required concentration timeseries using an energy balance model fitted to a commonly-performed AOGCM experiment (instantaneous CO2 quadrupling). We present the calibrated energy balance model parameters for all available CMIP6 models. The second method uses adaptive control to maintain the desired temperature. We compare the properties of our two methods with each other, and with a recently proposed emissions-driven method aiming at the same target temperature timeseries.