Energy Transition Divergence and Carbon Lock-in: A 50-Year Comparative Analysis of Japan, Australia, India, and South Africa (1970–2022)

Understanding why national decarbonization pathways diverge is essential for designing effective climate and energy policy. Using harmonized data for 1970–2022 from Our World in Data and the Maddison Project Database, this study examines long-run emission trends and electricity-mix transitions in four countries representing distinct energy regimes: Japan, Australia, India, and South Africa. We combine per-capita and total CO2 trajectories with a Kaya–LMDI decomposition aligned with updated methodological guidelines. Results reveal persistent and deepening transition divergence. Japan experienced partial decoupling before a nuclear vulnerability shock in 2011 reversed progress and temporarily increased fossil dependence. Australia shows a recent erosion of long-standing coal lock-in, driven by policy reform and falling renewable costs. India and South Africa remain highly coal-dependent, with population and income growth overwhelming improvements in energy intensity. Across countries, efficiency gains contributed to emission mitigation, but only structural changes in fuel mix produced sustained reductions in carbon intensity. Taken together, these findings suggest that divergent institutional and infrastructural lock-in conditions—rather than income levels alone—shape the pace, direction, and resilience of decarbonization. The study also speaks to recent international policy debates emphasized by the IPCC and the IEA, as well as to justice-oriented discussions in the energy transition literature. The results highlight major implications for climate policy, energy-system resilience, and just transition strategies.