Minisymposium: ‘Tipping Phenomena in Nonlinear Dynamical Systems: Theory and Applications’
Date:
Once ignited, peatland fires may smolder for months spewing out smoke, toxic fumes, and carbon dioxide. This phenomenon occurs across a diversity of regions such as Indonesia, Canada, Australia, and Siberia. With fire frequency expected to increase under climate change, the carbon released would be significant for the global climate–carbon cycle. Heat produced by microbial respiration is thought to be a key contributor, and this is the basis of the ‘Compost-Bomb’ instability, a theorized runaway heating of peat soils when atmospheric temperature rises faster than some critical rate, first proposed in [Luke & Cox, European Journal of Soil Science (2011), 62.1] and analysed in [Wieczorek et al, Proceedings of the Royal Society A (2011), 467.2129].
Here, the original soil carbon-temperature model of Luke & Cox is augmented with a non-monotonic microbial respiration function, for a more realistic process representation. This gives rise to a meta-stable state, reproducing the results of [Khvorostyanov et al, Tellus (2008), 60B] where a complex PDE model is used. Two non-autonomous climate forcings are examined: (i) a rise in mean air temperature over decades (ii) a short-lived extreme weather event, with the rate-induced compost bomb observed in each. Using techniques of compactification, singular perturbation and rate-induced tipping, we reduce the compost-bomb problem to one of heteroclinic orbits, uncovering the tipping mechanism for each climate change scenario.