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Observational constraints reduce model spread but not uncertainty in global wetland methane emission estimates

Chang, Kuang Yu ; Riley, William J. ; Collier, Nathan ; McNicol, Gavin ; Fluet-Chouinard, Etienne ; Knox, Sara H. ; Delwiche, Kyle B. ; Jackson, Robert B. ; Poulter, Benjamin and Saunois, Marielle , et al. (2023) In Global Change Biology 29(15). p.4298-4312
Abstract

The recent rise in atmospheric methane (CH4) concentrations accelerates climate change and offsets mitigation efforts. Although wetlands are the largest natural CH4 source, estimates of global wetland CH4 emissions vary widely among approaches taken by bottom-up (BU) process-based biogeochemical models and top-down (TD) atmospheric inversion methods. Here, we integrate in situ measurements, multi-model ensembles, and a machine learning upscaling product into the International Land Model Benchmarking system to examine the relationship between wetland CH4 emission estimates and model performance. We find that using better-performing models identified by observational constraints reduces the... (More)

The recent rise in atmospheric methane (CH4) concentrations accelerates climate change and offsets mitigation efforts. Although wetlands are the largest natural CH4 source, estimates of global wetland CH4 emissions vary widely among approaches taken by bottom-up (BU) process-based biogeochemical models and top-down (TD) atmospheric inversion methods. Here, we integrate in situ measurements, multi-model ensembles, and a machine learning upscaling product into the International Land Model Benchmarking system to examine the relationship between wetland CH4 emission estimates and model performance. We find that using better-performing models identified by observational constraints reduces the spread of wetland CH4 emission estimates by 62% and 39% for BU- and TD-based approaches, respectively. However, global BU and TD CH4 emission estimate discrepancies increased by about 15% (from 31 to 36 TgCH4 year−1) when the top 20% models were used, although we consider this result moderately uncertain given the unevenly distributed global observations. Our analyses demonstrate that model performance ranking is subject to benchmark selection due to large inter-site variability, highlighting the importance of expanding coverage of benchmark sites to diverse environmental conditions. We encourage future development of wetland CH4 models to move beyond static benchmarking and focus on evaluating site-specific and ecosystem-specific variabilities inferred from observations.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
benchmarking, bottom-up models, eddy covariance, methane emissions, observational constraints, top-down models, wetland modeling
in
Global Change Biology
volume
29
issue
15
pages
15 pages
publisher
Wiley-Blackwell
external identifiers
  • pmid:37190869
  • scopus:85159324024
ISSN
1354-1013
DOI
10.1111/gcb.16755
language
English
LU publication?
yes
additional info
Funding Information: This study was funded by the RUBISCO SFA of the Regional and Global Modeling Analysis (RGMA)and the E3SM program in the U.S. Department of Energy Office of Science under contract DE‐AC02‐05CH11231. This work was also conducted as a part of the Wetland FLUXNET Synthesis for Methane Working Group supported by the John Wesley Powell Center for Analysis and Synthesis of the U.S. Geological Survey. The compilation of the FLUXNET‐CH data is supported by the Gordon and Betty Moore Foundation through Grant GBMF5439 “Advancing Understanding of the Global Methane Cycle” to Stanford University supporting the Methane Budget activity for the Global Carbon Project ( globalcarbonproject.org ). We acknowledge the FLUXNET‐CH community product (Delwiche et al., 2021 ) and Global Carbon Project CH modeling group (Saunois et al., 2020 ) for the data provided in this analysis. We thank Peter Bergamaschi for sharing the TM5‐CAMS model data used in this study. FJ acknowledges support by the Swiss National Science Foundation (#200020_200511). FM and CP acknowledge the National Computational Infrastructure of the National Computational Infrastructure of the Australian Government through the NCMAS Allocation Scheme (grant NCMAS‐2021‐78), and the Sydney Informatics Hub HPC Allocation Scheme supported by the Office of the Deputy Vice‐Chancellor (Research). N.G. acknowledges support from the Newton Fund through the Met Office Climate Science for Service Partnership Brazil (CSSP Brazil). 4 4 4 Publisher Copyright: © 2023 John Wiley & Sons Ltd.
id
82fef8d4-e649-4b5e-af07-32284c36e6eb
date added to LUP
2023-05-29 16:30:21
date last changed
2024-06-15 03:32:11
@article{82fef8d4-e649-4b5e-af07-32284c36e6eb,
  abstract     = {{<p>The recent rise in atmospheric methane (CH<sub>4</sub>) concentrations accelerates climate change and offsets mitigation efforts. Although wetlands are the largest natural CH<sub>4</sub> source, estimates of global wetland CH<sub>4</sub> emissions vary widely among approaches taken by bottom-up (BU) process-based biogeochemical models and top-down (TD) atmospheric inversion methods. Here, we integrate in situ measurements, multi-model ensembles, and a machine learning upscaling product into the International Land Model Benchmarking system to examine the relationship between wetland CH<sub>4</sub> emission estimates and model performance. We find that using better-performing models identified by observational constraints reduces the spread of wetland CH<sub>4</sub> emission estimates by 62% and 39% for BU- and TD-based approaches, respectively. However, global BU and TD CH<sub>4</sub> emission estimate discrepancies increased by about 15% (from 31 to 36 TgCH<sub>4</sub> year<sup>−1</sup>) when the top 20% models were used, although we consider this result moderately uncertain given the unevenly distributed global observations. Our analyses demonstrate that model performance ranking is subject to benchmark selection due to large inter-site variability, highlighting the importance of expanding coverage of benchmark sites to diverse environmental conditions. We encourage future development of wetland CH<sub>4</sub> models to move beyond static benchmarking and focus on evaluating site-specific and ecosystem-specific variabilities inferred from observations.</p>}},
  author       = {{Chang, Kuang Yu and Riley, William J. and Collier, Nathan and McNicol, Gavin and Fluet-Chouinard, Etienne and Knox, Sara H. and Delwiche, Kyle B. and Jackson, Robert B. and Poulter, Benjamin and Saunois, Marielle and Chandra, Naveen and Gedney, Nicola and Ishizawa, Misa and Ito, Akihiko and Joos, Fortunat and Kleinen, Thomas and Maggi, Federico and McNorton, Joe and Melton, Joe R. and Miller, Paul and Niwa, Yosuke and Pasut, Chiara and Patra, Prabir K. and Peng, Changhui and Peng, Sushi and Segers, Arjo and Tian, Hanqin and Tsuruta, Aki and Yao, Yuanzhi and Yin, Yi and Zhang, Wenxin and Zhang, Zhen and Zhu, Qing and Zhu, Qiuan and Zhuang, Qianlai}},
  issn         = {{1354-1013}},
  keywords     = {{benchmarking; bottom-up models; eddy covariance; methane emissions; observational constraints; top-down models; wetland modeling}},
  language     = {{eng}},
  number       = {{15}},
  pages        = {{4298--4312}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Global Change Biology}},
  title        = {{Observational constraints reduce model spread but not uncertainty in global wetland methane emission estimates}},
  url          = {{http://dx.doi.org/10.1111/gcb.16755}},
  doi          = {{10.1111/gcb.16755}},
  volume       = {{29}},
  year         = {{2023}},
}