Abstract
Large across-model spread in simulating land carbon (C) dynamics has been ubiquitously demonstrated in model intercomparison projects (MIPs), and became a major impediment in advancing climate change prediction. Thus, it is imperative to identify underlying sources of the spread. Here, we used a novel matrix approach to analytically pin down the sources of across-model spread in transient peatland C dynamics in response to a factorial combination of two atmospheric CO2 levels and five temperature levels. We developed a matrix-based MIP by converting the C cycle module of eight land models (i.e., TEM, CENTURY4, DALEC2, TECO, FBDC, CASA, CLM4.5 and ORCHIDEE) into eight matrix models. While the model average of ecosystem C storage was comparable to the measurement, the simulation differed largely among models, mainly due to inter-model difference in baseline C residence time. Models generally overestimated net ecosystem production (NEP), with a large spread that was mainly attributed to inter-model difference in environmental scalar. Based on the sources of spreads identified, we sequentially standardized model parameters to shrink simulated ecosystem C storage and NEP to almost none. Models generally captured the observed negative response of NEP to warming, but differed largely in the magnitude of response, due to differences in baseline C residence time and temperature sensitivity of decomposition. While there was a lack of response of NEP to elevated CO2 (eCO2) concentrations in the measurements, simulated NEP responded positively to eCO2 concentrations in most models, due to the positive responses of simulated net primary production. Our study used one case study in Minnesota peatland to demonstrate that the sources of across-model spreads in simulating transient C dynamics can be precisely traced to model structures and parameters, regardless of their complexity, given the protocol that all the matrix models were driven by the same gross primary production and environmental variables.
| Original language | English |
|---|---|
| Pages (from-to) | 2759-2775 |
| Number of pages | 17 |
| Journal | Global Change Biology |
| Volume | 29 |
| Issue number | 10 |
| DOIs | |
| State | Published - May 2023 |
Funding
The authors thank Ning Wei for discussion on the work, and Professor Nigel Roulet and two anonymous reviewers for their constructive comments on this manuscript. This study was supported by the National Natural Science Foundation of China (32271644, 31870464), Guangdong Basic and Applied Basic Research Foundation (2022B1515020014), National Science Foundation Grant DEB (1655499; 2017884), US Department of Energy (DOE), Terrestrial Ecosystem Sciences Grant (DE‐SC0020227), and the subcontract 4000158404 from Oak Ridge National Laboratory (ORNL) to Northern Arizona University. ORNL's work was supported by DOE, Office of Science, Office of Biological and Environmental Research. ORNL is managed by UT‐Battelle, LLC, for DOE under contract DE‐AC05‐00OR22725. Hyung‐Sub Kim was supported by the National Research Foundation of Korea (NRF‐2018R1A2B6001012). Efrén López‐Blanco and Mathew Williams thank Luke Smallman for support in calibrating the DALEC2 model for the site. Efrén López‐Blanco has received funding from GreenFeedBack (Greenhouse gas fluxes and earth system feedbacks) funded by the European Union's HORIZON research and innovation program under grant agreement No 101056921. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. The authors thank Ning Wei for discussion on the work, and Professor Nigel Roulet and two anonymous reviewers for their constructive comments on this manuscript. This study was supported by the National Natural Science Foundation of China (32271644, 31870464), Guangdong Basic and Applied Basic Research Foundation (2022B1515020014), National Science Foundation Grant DEB (1655499; 2017884), US Department of Energy (DOE), Terrestrial Ecosystem Sciences Grant (DE-SC0020227), and the subcontract 4000158404 from Oak Ridge National Laboratory (ORNL) to Northern Arizona University. ORNL's work was supported by DOE, Office of Science, Office of Biological and Environmental Research. ORNL is managed by UT-Battelle, LLC, for DOE under contract DE-AC05-00OR22725. Hyung-Sub Kim was supported by the National Research Foundation of Korea (NRF-2018R1A2B6001012). Efrén López-Blanco and Mathew Williams thank Luke Smallman for support in calibrating the DALEC2 model for the site. Efrén López-Blanco has received funding from GreenFeedBack (Greenhouse gas fluxes and earth system feedbacks) funded by the European Union's HORIZON research and innovation program under grant agreement No 101056921. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
| Funders | Funder number |
|---|---|
| GreenFeedBack | 101056921 |
| Professor Nigel Roulet | |
| National Science Foundation | 2017884, DEB (1655499 |
| U.S. Department of Energy | DE‐SC0020227, 4000158404 |
| National Aeronautics and Space Administration | |
| Office of Science | |
| Biological and Environmental Research | DE‐AC05‐00OR22725 |
| Oak Ridge National Laboratory | |
| Northern Arizona University | |
| National Natural Science Foundation of China | 31870464, 32271644 |
| National Research Foundation of Korea | NRF‐2018R1A2B6001012 |
| Basic and Applied Basic Research Foundation of Guangdong Province | 2022B1515020014 |
Keywords
- SPRUCE experiment
- across-model spread
- carbon residence time
- environmental scalar
- land carbon dynamics
- matrix model
- traceability analysis
