Time is of the essence: Accounting for observed past transformation progress in the ex-ante assessment of climate policies with integrated assessment models

Years of delay in taking meaningful action on climate change, combined with the increasing impetus to pursue the goal of limiting warming to 1.5°C, have compressed the timescale for decarbonizing the energy system to net-zero to a few decades. The focus of research must therefore shift from the fundamental long-term characteristics of net-zero energy systems to the dynamics of the near-term energy transition.
In this study, we present a detailed assessment of the near-term sector- and technology-specific transformation patterns of modeled energy-economy pathways consistent with the climate targets of the Paris Agreement, and contrast it to the scale-up of innovative climate change mitigation technologies and the phase-out of fossil fuels observed in real-world energy systems.
This approach allows us to (1) derive estimates of the transformation gap, i.e., the discrepancy between real-world mitigation progress and the near-term transformations needed to meet climate targets; (2) use differences in transformation gaps across sectors and technologies to assess which technologies and policies have the greatest potential for accelerated deployment; and (3) derive improved 1.5-2°C pathways that are more consistent with observed transformation patterns
In comparing recent trends with mitigation scenarios, we find that the observed upscaling of solar PV, wind power, and electric vehicles is broadly consistent with model-derived transformation pathways. In contrast, real-world carbon capture and storage (CCS) and nuclear power deployment tend to be far slower than in scenarios. Fossil fuel consumption also continues to grow, in sharp contrast to the phase-out requirements of the 1.5°C limit.
Based on the findings of the technology gap analysis and using the REMIND integrated assessment model, we derive new 1.5°C pathways that further accelerate scale-up of technologies with rapid deployment characteristics, while also accounting for the inertia upscaling of more complex technology systems such as CCS or hydrogen.