Climate policy curves highlight key mitigation choices

The extent of future climate change is largely a policy choice. We illuminate this choice with <i>climate policy curves</i> (CPCs), which link climate policies to subsequent global temperatures. The estimated downward sloping CPCs highlight the key trade-off between initial policy ambition, expressed via an overall effective carbon price, and the subsequent policy burden left for future generations. We also demonstrate how different CPCs can illustrate the range of climate policy paths towards attaining the Paris Agreement temperature goals. Based on the latest Intergovernmental Panel on Climate Change (IPCC) integrated-assessment model scenarios, we estimate an implicit CPC, which provides a high-level summary of assumptions underlying the IPCC’s assessment about climate policy trade-offs. We show that by virtue of their reductionism, CPCs serve as a useful model diagnostic and communication tool for climate policy discussions. <b>Key policy insights</b>Climate Policy Curves (CPCs) are a simple, new heuristic device for quantifying projected climate outcomes of different climate policies.CPCs can elucidate the various uncertainties surrounding climate policies and crystalize the importance of comparing climate policy today with its future path.CPCs can serve as a model diagnostic and communication tool for climate policy discussions by helping to understand and evaluate policy implications of alternative climate-economy models. Climate Policy Curves (CPCs) are a simple, new heuristic device for quantifying projected climate outcomes of different climate policies. CPCs can elucidate the various uncertainties surrounding climate policies and crystalize the importance of comparing climate policy today with its future path. CPCs can serve as a model diagnostic and communication tool for climate policy discussions by helping to understand and evaluate policy implications of alternative climate-economy models.