Design and Assessment of Global Emission Reduction Pathways

This chapter evaluates the outcomes of the Kyoto Protocol and Paris Agreement in global emission reduction and pathway design. The study shows that the Kyoto Protocol’s “top-down” mechanism reduced emissions in some countries, yet its misaligned targets (e.g., Australia) limited overall effectiveness. The Paris Agreement’s “bottom-up” NDC approach faces challenges, as current commitments meet only one-third of the 2 °C target’s requirements, with major emitters (China, the United States, India) contributing inadequately. Simulations using the C3IAM model reveal that under current NDCs, global emissions will reach 50.5 billion tons of CO₂ equivalent by 2030, leaving gaps of 12.9–18.1 and 29–34 billion tons for the 2 °C and 1.5 °C targets, respectively. A “self-preservation strategy” is proposed, requiring enhanced efforts through technological advancement and upfront investments. Results indicate an additional 19–30 billion tons of CO₂ equivalent must be reduced by 2030, with all nations achieving cumulative net benefits by 2100 (0.46–5.24% of GDP). The study emphasizes the need for developed countries to lead in net-negative emissions and support vulnerable nations through international cooperation, alongside dynamic NDC upgrades.