Committed and projected future changes in global peatlands – continued transient model simulations since the Last Glacial Maximum

Abstract

Abstract. Peatlands are diverse wetland ecosystems distributed mostly over the northern latitudes and tropics. Globally they store a large portion of the global soil organic carbon and provide important ecosystem services. The future of these systems under continued anthropogenic warming and direct human disturbance has potentially large impacts on atmospheric CO2 and climate. We performed global long-term projections of peatland area and carbon over the next 5000 years using a dynamic global vegetation model forced with climate anomalies from 10 models of the Coupled Model Intercomparison Project (CMIP6) and three standard future scenarios. These projections are seamlessly continued from a transient simulation from the Last Glacial Maximum to the present to account for the full transient history and are continued beyond 2100 with constant boundary conditions. Our results suggest short to long-term net losses of global peatland area and carbon, with higher losses under higher-emission scenarios. Large parts of today's active northern peatlands are at risk, whereas peatlands in the tropics and, in case of mitigation, eastern Asia and western North America can increase their area and carbon stocks. Factorial simulations reveal committed historical changes and future rising temperature as the main driver of future peatland loss and increasing precipitations as the driver for regional peatland expansion. Additional simulations forced with climate anomalies from a subset of climate models which follow the extended CMIP6 scenarios, transient until 2300, show qualitatively similar results to the standard scenarios but highlight the importance of extended transient future scenarios for long-term carbon cycle projections. The spread between simulations forced with different climate model anomalies suggests a large uncertainty in projected peatland changes due to uncertain climate forcing. Our study highlights the importance of quantifying the future peatland feedback to the climate system and its inclusion into future earth system model projections.

Warming-induced vegetation growth cancels out soil carbon-climate feedback in the northern Asian permafrost region in the 21st century

“…Our results indicated that TAS and SMN were the primary drivers of soil, litter, and vegetation C pools in NAPR during future periods. This was in line with previous findings (Natali et al 2015, Salmon et al 2016, Schädel et al 2016, Song et al 2018, Müller and Joos 2021. Increasing soil temperature with climate warming leads to deepening soil active layer (Biskaborn et al 2019) and altering the decomposition of soil organic matter (Treat et al 2014).…”

Modeling Pan‐Arctic Peatland Carbon Dynamics Under Alternative Warming Scenarios

“…Studies have indicated that peatlands will continue to act as carbon sinks in the next decades under different warming scenarios, but there is a possibility that they become carbon neutral or even a minor carbon source by the end of this century (Chaudhary et al, 2017b(Chaudhary et al, , 2020Gallego-Sala et al, 2018;Qiu et al, 2020). To quantify and understand the overall effects of these rapid changes, various advanced peatland models have been employed, but often these models are forced with limited set of Representative Concentration Pathway (RCP) scenarios (Chaudhary et al, 2020;Müller & Joos, 2021;Qiu et al, 2020). It is a common trend to focus on two-three scenarios in modeling studies in order to obtain end-member estimates.…”

Tropical Peatland Hydrology Simulated With a Global Land Surface Model

“…With the development of PEATCLSM Trop , we integrated peat‐specific hydrology modules for natural and drained tropical peatlands into a global LSM for the first time. These modules facilitate the integration of tropical peatland hydrology into Earth system models, possibly resulting in better understanding and projecting current and future global C fluxes (Loisel et al., 2021 ; Müller & Joos, 2021 ). Peatland hydrology and C dynamics are intrinsically linked, including in tropical peatlands where water level dynamics are the main force driving long‐term peat C sequestration (Cobb et al., 2017 ; Couwenberg et al., 2010 ; Dargie et al., 2017 ).…”