Preprints
https://doi.org/10.5194/egusphere-2022-1006
https://doi.org/10.5194/egusphere-2022-1006
 
30 Sep 2022
30 Sep 2022

Peatlands and their carbon dynamics in northern high latitudes from 1990 to 2300: A process-based biogeochemistry model analysis

Bailu Zhao1 and Qianlai Zhuang1,2 Bailu Zhao and Qianlai Zhuang
  • 1Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA
  • 2Department of Agronomy, Purdue University, West Lafayette, IN 47907, USA

Abstract. Northern peatlands are a large C sink during the Holocene, but whether they will keep being a C sink under future climate change is uncertain. This study simulates the responses of northern peatlands to future climate until 2300 with a Peatland version Terrestrial Ecosystem Model (PTEM). The simulations are driven with two sets of CMIP5 climate data (IPSL-CM5A-LR and bcc-csm1-1) under three warming scenarios (RCP2.6, 4.5 and 8.5). Peatlands expansion, shrink, accumulation and decomposition are modeled. In the 21st century, northern peatlands are projected to be a C source of 1.2–13.3 Pg C under all climate scenarios except for RCP 2.6 of bcc-csm1-1 (a sink of 0.8 Pg C). During 2100–2300, northern peatlands under all scenarios are a C source under IPSL-CM5A-LR scenarios, being larger sources than bcc-csm1-1 scenarios (5.9–118.3 vs. 0.7–87.6 Pg C). The peatland being C sources are due to: 1) water table depth (WTD) becomes deeper and permafrost thaw increases decomposition rate; 2) net primary production (NPP) does not increase much as climate warms because peat drying suppresses net N mineralization and 3) as WTD deepens, peatlands switches from moss-herbaceous dominated to moss-woody dominated, while woody plants require more N for productivity. Under IPSL-CM5A-LR scenarios, northern peatlands remain as a C sink until pan-Arctic annual temperature reaches -2.6–-2.89°C, while this threshold is -2.09–-2.35°C under bcc-csm1-1 scenarios. This study predicts an earlier northern peatland sink to source shift than previous estimates in the literature and emphasizes the vulnerability of northern peatlands to climate change.

Bailu Zhao and Qianlai Zhuang

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-1006', Anonymous Referee #1, 15 Nov 2022
  • RC2: 'Comment on egusphere-2022-1006', Anonymous Referee #2, 16 Nov 2022
  • RC3: 'Comment on egusphere-2022-1006', Anonymous Referee #3, 17 Nov 2022

Bailu Zhao and Qianlai Zhuang

Bailu Zhao and Qianlai Zhuang

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Short summary
In this study, we use a process-based model to simulate the northern peatland's C dynamics in response future climate change during 1990–2300. Northern peatlands are projected to be a C source under all climate scenarios except for the mildest one before 2100, and C sources under all scenarios afterwards. We find northern peatlands are a C sink until pan-Arctic annual temperature reaches -2.09~ -2.89 °C. This study emphasizes the vulnerability of northern peatlands to climate change.