Atmospheric CO₂ decline retains memory of past emissions
Year: 2026
Type: preprint
Abstract: Atmospheric CO₂ decline is a state-dependent first-passage transition that retains dynamically relevant memory of past emissions. In FaIR, two pathways with exactly equal cumulative fossil emissions (1532.094261 GtCO₂) yield persistent-three turning in 78/841 versus 804/841 calibrated configurations. A second pair preserves fossil-source dominance year by year, yet the higher-source pathway turns earlier in 107 configurations and later in none. Independently, AERA-MIP GFDL-ESM2M provides a full-ESM counterexample: the pathway with higher fossil emissions throughout 2026–2150 begins persistent-five atmospheric CO₂ decline in 2079 rather than 2103. After paired sources converge, net uptake remains higher in all 21,025 post-convergence FaIR member-years, locating the mechanism in inherited carbon-cycle state. Across continuous deformations and alternative backgrounds, the first-passage boundary moves while carbon-cycle susceptibility remains nearly rank-invariant. Version 2.0 substantially revises and expands Version 1.0 with strengthened mechanistic framing, cross-model evidence, robustness analysis and explicit claim boundaries.
Author: Navalón Fernández, Juan
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: green
OpenAlex ID: W7203860114
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