Rate-Induced Tipping to Metastable Zombie Fires

The paper compactifies a nonautonomous fast–slow soil-carbon model and uses geometric singular perturbation theory to reduce R-tipping via quasithresholds to heteroclinic connections—folded singularities in the reduced flow for r≈O(1) and a saddle-to-saddle connection in the layer problem for r≈O(1/ε). It further shows that quasithresholds yield critical ranges of rates organised by families of canards, with three slow-regime cases (FS, FN, FSN‑I) and one fast-regime case; all are evidenced in the text and diagrams. The candidate solution reproduces these constructions and classifications essentially verbatim, with only minor omissions of technical hypotheses (e.g., ν∈(0,ρ], transversality). Hence, both are correct and closely aligned.