Rate-induced tipping to metastable Zombie fires

Zombie fires in peatlands disappear from the surface, smoulder underground during winter, and ‘come back to life’ spring. They can release hundreds of megatonnes carbon into atmosphere per year are believed be caused by surface wildfires. Here, we propose rate-induced tipping (R-tipping) a subsurface hot metastable state bioactive peat soils as main cause fires. Our hypothesis is based on conceptual soil-carbon model subjected realistic changes weather climate patterns, including global warming scenarios summer heatwaves. Mathematically speaking, R-tipping genuine nonautonomous instability, due crossing an elusive quasi-threshold, multiple-timescale dynamical system. To explain this provide framework combining special compactification technique with concepts geometric singular perturbation theory. This allows us reduce problem quasi-threshold heteroclinic orbit limit. We identify generic cases tracking–tipping transitions via: (i) unfolding codimension-two folded-saddle-node type-I singularity for (ii) analysis codimension-one saddle-to-saddle hetroclinic heatwaves, turn revealing new types excitability quasi-thresholds.