The Bern Simple Climate Model (BernSCM) is a free open-source re-implementation of a reduced-form carbon cycle–climate model widely used in science and IPCC assessments. BernSCM supports up to decadal time steps with high accuracy and is suitable for studies with high computational load, e.g., integrated assessment models (IAMs). Further applications include climate risk assessment in a business, public, or educational context and the estimation of benefits of emission mitigation options.