These .json files provides the 2237 ensemble members that are used to run the FaIR simple climate model in the IPCC's Sixth Assessment Report contributions to Working Group 1 and Working Group 3. v1.1 of this dataset includes two versions of the files: the original full parameter set `fair-1.6.2-wg3-params.json` as in v1.0 reduced file size versions `fair-1.6.2-wg3-params-slim.json` and `fair-1.6.2-wg3-params-common.json` where only the parameters that vary between ensemble members are included in the former and everything else is in the latter. This is optimised for running the Working Group 3 climate assessment. Drawn from an initial prior ensemble of 1 million, the following constraints are placed upon the results: representation of observed warming from 1850-2019, within observational uncertainty representation of observed ocean heat content change 1971-2018, within observational uncertainty reproduction of near-present day atmospheric concentrations of CO2 from the carbon cycle airborne fraction of CO2 with a distribution similar to the assessed range of Chapter 5, IPCC Working Group 1 AR6 equilibrium climate sensitivity with a similar distribution to Chapter 7, IPCC Working Group 1, AR6 transient climate response with a similar distribution to Chapter 7, IPCC Working Group 1, AR6 projected future warming that is of a similar distribution to the SSP scenarios of Chapter 4, IPCC Working Group 1, AR6, when run with prescribed concentrations Changelog v1.1: inclusion of lightweight parameter sets. v1.0: original upload full parameter sets.