This release is the effective radiative forcing from SSPs to be used in RCMIP Phase 1. It is consistent with the latest AR6 estimates between 1750 and 2014 (and CMIP6 forcing datasets, where possible, between 1850 and 2014), but for the following small differences: GHGs in this dataset are based on concentrations from Meinshausen et al. (2017), whereas AR6 ERF time series are based on more recent observations in AR6. stratospheric ozone and stratospheric water vapour ERF depend on GHG concentrations, and follow Meinshausen et al. (2017) here rather than AR6 values. Other updates compared to v0.3.1: add "year" column for better integration with pandas (fix #2) volcanic ERF fixed to rebase to long-term average of zero (meaning positive offset for quiescent years) and ramp down over 10 years to zero from 2014 (partial fix of #3) ozone relationships based on CMIP6 datasets for historical period (fix #6) some columns have been given more descriptive names "present day" for forcing categories that are assessed in AR6 is defined to be year 2018 in SSP2-4.5. This differs from v0.3.1 which used SSP5-8.5 for year 2017. AR6 now defines 2018 for recent estimates, and my best estimate of transient future aerosol forcing is from SSP2-4.5 simulations which is why the change has been made. Impacts are minimal. As a further note, ERFs are substantially higher than the nameplate RFs for year 2100. Much of this stems from an increase in ERF compared to stratospherically-adjusted RF (SARF) when taking into account rapid adjustments from greenhouse gases, and new relationships for SARF derived from Etminan et al., (2016). Taking this into account, modellers may wish to use the latest best-estimate doubled-CO2 ERF of 4.01 W/m2 in their setups where this is a free parameter and important (e.g. for calculating climate feedbacks, or ECS).