Simple climate model

This Excel-file contains a simple climate model that can be used to assess climate impacts, in terms of radiative forcing and global mean temperature change, from an emission profile of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). It is an update of the model used for the publication by Persson et al. (2015), and has been revised to reflect the equations and parametrizations used for estimating greenhouse gas metrics in the latest IPCC assessment (Forster & Storelvmo et al. 2021), including the carbon cycle feedback effects of CH4 and N2O emissions. To use the model, enter emission pathways for carbon dioxide (column B), methane (column O), and nitrous oxide (column AF), and the model calculates the resulting impacts in terms of radiative forcing (columns L, AC, and AT, respectively) and temperature change (columns M, AD, and AU, respectively). As is, the model is run with a pulse emission of one ton for each gas in year 1, which means the results can be used to estimate the Global Warming Potential (GWP) and Global Temperature Potential (GTP) for methane and nitrous oxide (columns AW-AZ). Note that the model is a linearized representation of more complex climate models, and as such should be used to assess the climate impacts for small perturbations (i.e., project level emissions scenarios). For larger perturbations (e.g., regional or global emission scenarios) a model that includes the non-linear responses of the climate system (e.g., on greenhouse gas lifetimes and radiative forcings), such as the FAIR model (Smith et al. 2017, 2018) should be used