The team of researchers on this activity will evaluate the environmental (non)equivalence among CDR options, and between CDR pathways vs. competing mitigation options. We will first establish a set of aggressive rollout scenarios and resulting changes to climate forcing associated with each CDR pathway. We will use a set of Earth System Models to simulate the overall climate impact of each CDR scenario. Results will be translated into effectiveness metrics to quantify the effect of a given technology on surface air temperature and other climate metrics. Finally, we will conduct a screening analysis to evaluate other environmental costs and co-benefits associated with CDR compared with other potential mitigation options.