We investigate how uncertainties in key parameters in the carbon cycle and climate system propagate to the costs of climate change mitigation and adaptation needed to achieve the 2 and 1.5 °C targets. This study aims to provide a comprehensive understanding of the impact of climate-related uncertainties on the costs of climate change mitigation and adaptation. The results of this study will be useful for policymakers and stakeholders to make informed decisions about climate change mitigation and adaptation strategies.