Solar Geoengineering Likely up to 14 Times More Efficient than CDR: Albedo Misrepresentations in Climate Forcing and Governance - Preprint

[Geoengineering News]

https://www.researchgate.net/publication/394470822_Solar_Geoengineering_Likely_up_to_14_Times_More_Efficient_than_CDR_Albedo_Misrepresentations_in_Climate_Forcing_and_Governance

Authors: Alec Feinberg

August 2025

Abstrct

This study introduces a steady-state, physics-based Unsaturated Linear Forcing (ULF) model that treats each added unit of greenhouse gas (GHG) as having equal thermodynamic forcing potential. By assuming linear amplification within the natural GHG system, the ULF framework provides first-order, feedback-free forcing estimates. Because logarithmic saturation in standard GHG forcing formulas (e.g., AR6) tends to lower increments at higher concentrations, the ULF model is expected to give upper-bound forcing values. Surprisingly, combined ULF estimates for CO₂, CH₄, N₂O, and O₃ are ~39% lower than the IPCC AR6 central estimates for 1750–2019, with the ULF doubling estimate for CO₂ ~11% lower. This paradox highlights the diagnostic value of simple bounding models that indicates discrepancies with AR6 estimates that should be addressed. Using this framework, solar geoengineering (SG) is found to be likely up to ~12.6–13.8 times more efficient than carbon dioxide removal (CDR), with CDR cooling 85–93% less effective. General GHG removal is ~60% less efficient, making SG up to 2.6 times more effective. The analysis reveals a fundamental asymmetry: Earth responds more strongly to changes in incoming shortwave radiation (albedo) than to changes in outgoing longwave radiation affected by GHGs. These findings underscore an overlooked global albedo crisis. Declining planetary albedo, rapid warming, and urban albedo abuse practices such as dark pavements, roofs, and vehicles are intensifying surface heating, yet remain under-regulated despite cost-effective alternatives. Misrepresentations include satellite-based claims downplaying urbanization’s role in warming contributions especially given alternate studies and their measurement challenges resolving UHI vertical structures area albedo corrections and lack of ERF measurement capabilities compared to ground-based studies. SG should therefore be viewed not as a temporary “Band-Aid” but as a premier mitigation tool. A sustained Annual SG strategy is recommended that combines surface brightening, space-based sunshading, and stratospheric aerosol injection (SAI), especially in the polar regions offering urgent, high-leverage mitigation at a time when delays carry the greatest risks.

Source: ResearchGate