Deep mitigation of CO2 and non-CO2 greenhouse gases toward 1.5°C and 2°C futures
Stabilizing climate change well below 2°C and towards 1.5°C requires the combined mitigation of CO2 and non-CO2 GHG emissions. Here we fully incorporate the latest global non-CO2 emissions and mitigation data into a state-of-the-art integrated assessment model GCAM and examine 90 mitigation scenarios pairing different levels of CO2 and non-CO2 GHG abatement pathways. We estimate that when non-CO2 mitigation contributions are not fully implemented, the timing of net-zero CO2 must occur about two decades earlier. Conversely, comprehensive GHG abatement that fully incorporates non-CO2 mitigation measures in addition to a net-zero CO2 commitment facilitates a more moderate decline in emissions on the pathway to 1.5°C stabilization. While decarbonization-driven fuel switching mostly reduces non-CO2 emissions from fuel extraction and end use, targeted non-CO2 mitigation measures can significantly reduce fluorinated gas emissions from industrial processes and cooling sectors. Our study provides direct insights in how system-wide all non-CO2 GHG mitigation can affect the timing of net-zero CO2 for 1.5°C and 2°C climate change scenarios.