Patterns of global peat chemistry suggest a novel temperature-dependent carbon cycling mechanism

Peatlands contain a disproportionate share of global carbon stocks, such that their biogeochemistry plays an outsized role in carbon balance and climate regulation. The precise mechanisms underpinning peat formation and stabilisation are not yet clear, with several hypotheses co-existing. Further opacity stems from a strong historical bias in research efforts towards boreal and temperate peatlands in the Northern Hemisphere, leaving the tropical case relatively under-studied. On the basis of the economics of oxidative decomposition and juxtaposition of chemical compositional data from tropical peatlands and northern peatlands, we make the case that a rapid, globally-consequential but as yet unidentified endergonic oxidation process must be occurring in tropical but not cold-climate peatlands. We suggest that low temperature limits this process in northern peatlands and, therefore, that a significant quantity of carbon in these systems is more vulnerable to warming than previously thought. We conclude that the existence of tropical peatlands - and their role in regulating global climate - may be partially underwritten by a mechanism largely unmapped by our current knowledge of soil carbon turnover.