Feedback Trends with ECS from Energy Rates: Feedback Doubling and the Vital Need for Solar Geoengineering
Authors: Feinberg Alec 
Published: February 2025

This paper provides climate feedback trends, quantifies the feedback-doubling (FD) period, considers urbanization influences, and provides related equilibrium climate sensitivity (ECS) estimates using data from 1880 to 2024. Data modeling is accomplished by focusing on statistically significant stable normalized correlated rates (NCRs, i.e., normalized related slopes). Estimates indicate that the global warming NCR is increasing by a factor of 1.65 to 2.33 times faster than the energy consumption NCR, from 1975 to 2024. The reason is feedback amplification. This is supported by the fact that the NCR for forcing and energy consumption shows approximate equivalency in the period studied. Results provide feedback yearly trend estimates at the 95% confidence level that key results will fall within the IPCC AR6 likely range. The projected 2017–2024 feedback amplification estimates, using the EC approach, range from 2.0 to 2.16, respectively. A feedback amplification of 2.0 (approximately equal to −2.74 Wm−2 K−1) doubles the forcing, indicating that in 2024, more than half of global warming (53.7%) is likely due to feedback. Relative to the feedback-doubling (FD) threshold (i.e., the point where feedback exceeds forcing), the FD overage is 3.7% in 2024. This is the amount of feedback exceeding the forcing portion found to have a surprisingly aggressive 3.1% to 3.9% estimated overage growth rate per decade. We now ask, shouldn’t we try to mitigate feedback as well as GHG forcing, and if forcing could be removed, would global warming fully “self-mitigate”? Additionally, CO2 yearly increases are complex, with poor reduction progress. Therefore, this study’s risk assessment urgently recommends that supplementary “mild” annual solar geoengineering is necessary, to reduce the dominant aggressive feedback. SG reduces the primary solar warming source creating 62% higher mitigation efficiency than CDR. Urgency is enhanced since solar geoengineering must be timely and can take years to develop. This study also estimates that 75% to 90.5% (83% average) of the feedback problem is due to water vapor feedback (WVF). High WVF also plagues many cities needing local SG. Trend analysis indicates that by 2047, the earliest we may reach 10 billion people, feedback amplification could reach a value of 2.4 to 2.8. Furthermore, by 2082, the year estimated for 2× CO2, at the current rate, feedback amplification could range from 2.88 to 3.71. This yields an ECS range from 2.4 °C to 3.07 °C, in reasonable agreement with the reported estimated range in AR6. An overview of recent urbanization forcing attribution indicates the ECS value may be lower by 10.7% if this forcing is considered. For numerous reasons, the lack of albedo urbanization Earth brightening requirements in the Paris Agreement, is unsettling. In addition, a model assesses effective forced feedback (EFF) temperature characteristics of up to 1.9 °C, providing interesting feedback insights that may relate to high GW land and pipeline temperature estimates. Lastly in addition to urbanization, solar geoengineering in the Arctic and Antarctic is advised. Worldwide efforts in GHG mitigation, with no significant work in SG, appears highly misdirected.