Rate-induced tipping to metastable Zombie fires

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dc.contributor.advisorMulchrone, Kieran F.
dc.contributor.advisorWieczorek, Sebastian
dc.contributor.authorO'Sullivan, Eoinen
dc.contributor.funderATSR Ltd.
dc.date.accessioned2023-09-20T14:52:20Z
dc.date.available2023-09-20T14:52:20Z
dc.date.issued2023en
dc.date.submitted2023
dc.description.abstractSurface wildfires are generally believed to be the cause of so-called Zombie fires observed in peatlands, that disappear from the surface, smoulder underground during the winter, and ''come back to life" in the spring. Here, we propose rate-induced tipping (R-tipping) to a subsurface hot metastable state in bioactive peat soils as a main cause of Zombie fires. Our hypothesis is based on a conceptual soil-carbon model subjected to realistic changes in weather and climate patterns, including global warming scenarios and summer heatwaves. Mathematically speaking, R-tipping to the hot metastable state is a nonautonomous instability, due to crossing an elusive quasithreshold, in a multiple-timescale dynamical system. The instability is {\em reversible}, in the sense that the system eventually returns to its base state. To explain this instability, we provide a framework that combines a special compactification technique with concepts from geometric singular perturbation theory. This framework allows us to reduce a reversible R-tipping problem due to crossing a quasithreshold to a heteroclinic orbit problem in a singular limit. Thus, we identify generic cases of such R-tipping via: (i) unfolding of a codimension-two heteroclinic folded saddle-node type-I singularity for global warming, and (ii) analysis of a codimension-one saddle-to-saddle hetroclinic orbit for summer heatwaves, which in turn reveal new types of excitability quasithresholds.en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationO'Sullivan, E. G. 2023. Rate-induced tipping to metastable Zombie fires. PhD Thesis, University College Cork.
dc.identifier.endpage137
dc.identifier.urihttps://hdl.handle.net/10468/15016
dc.language.isoenen
dc.publisherUniversity College Corken
dc.rights© 2023, Eoin O'Sullivan.
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectApplied mathematics
dc.subjectZombie fires
dc.subjectRate-induced tipping
dc.subjectCanards
dc.subjectGeometric singular perturbation theory
dc.titleRate-induced tipping to metastable Zombie fires
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD - Doctor of Philosophyen
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