Deep mitigation of CO(2) and non-CO(2) greenhouse gases toward 1.5 °C and 2 °C futures

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