Here Today, Gone Tomorrow? Using Contrasting Peatland Histories To Determine Fate Of Permafrost Carbon With Future Climate Change And Permafrost Thaw

Abstract:

Climate warming in high-latitude regions has resulted in thawing of carbon-rich permafrost soils. Permafrost thaw can result in the decomposition of previously frozen soil organic matter, releasing CO₂ and CH₄, which can enhance climate warming. In permafrost peatlands, soil organic matter has been accumulating for several thousand years. The decomposability of the peat varies depending on the peatland history, vegetation type, level of previous decomposition, and timing of permafrost aggradation. Therefore, predicting the future climate feedbacks from permafrost thaw in peatlands is not straightforward. We use a coupled model of peatland and permafrost dynamics (Holocene Peat Model + GIPL-2) to examine the role of site history on the potential loss of soil carbon in permafrost with future climate warming in permafrost peatlands. We select sites with differing climates and permafrost histories from North America, Europe, and Asia and simulate peatland development from 12 kya to present. We then compare the magnitude of carbon loss at 2100 from thawed permafrost peats at these sites under future climate scenarios. While there are uncertainties associated with the climate drivers, we find that site history is an important determinant of the magnitude of carbon losses in the coming decades to centuries.