Co-Benefits of CO2 Mitigation for NOX Emission Reduction: A Research Based on the DICE Model

Actions to reduce carbon emissions often entail co-benefits for environmental protection, like air pollutants reduction. Previous studies made contributions to estimate these co-benefits, but few considered the feedbacks from the socioeconomic system and the natural system. This paper extends the Dynamic Integrated model of Climate and the Economy (DICE) model, a classical Integrated Assessment model (IAM), into the Dynamic Integrated model of Climate, Air pollution and the Economy (DICAE) model. Through the hard link between a new air pollution module and the other modules in the original DICE, this paper quantifies the co-benefits of mitigating CO2 emissions for NOX emission reduction, and compares the predicted climate change, economic output and social utility under seven mixed policy scenarios. In addition, uncertainty analysis based on Monte Carlo simulation is carried out to verify the robustness of the DICAE model. The results indicate that the NOX emissions co-emitted with CO2 emissions would be over 0.6 Gt/year in a no-policy scenario. In policy scenarios, mitigating CO2 emissions can simultaneously reduce at least 15% of the NOX emissions, and the more severe the climate mitigation target is, the more obvious co-benefits for NOX emission reduction. Although these co-benefits can offset some mitigation costs, it will not be cost-effective when NOX emission reduction is achieved completely depending on ambitious carbon mitigation, so the end-of-pipe technology for NOX emission is also indispensable. For policymakers, they should recognize the co-benefits of climate policies, actively taking mitigation actions. Moreover, they are encouraged to combine CO2 mitigation with NOX emission reduction and coordinate their policy intensities to make wise use of the co-benefits.