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Title: Evaluating the simulated mean soil carbon transit times by Earth system models using observations

Abstract

One known bias in current Earth system models (ESMs) is the underestimation of global mean soil carbon (C) transit time ( τ soil), which quantifies the age of the C atoms at the time they leave the soil. However, it remains unclear where such underestimations are located globally. Here, we constructed a global database of measured τ soil across 187 sites to evaluate results from 12 ESMs. The observations showed that the estimated τ soil was dramatically shorter from the soil incubation studies in the laboratory environment (median = 4 years; interquartile range = 1 to 25 years) than that derived from field in situ measurements (31; 5 to 84 years) with shifts in stable isotopic C( 13C) or the stock-over-flux approach. In comparison with the field observations, the multi-model ensemble simulated a shorter median (19 years) anda smaller spatial variation (6 to 29 years) of τ soil across the same site locations. We then found a significant and negative linear correlation between the in situ measured τ soil and mean annual air temperature. The underestimations of modeled τ soil are mainly located in cold and dry biomes, especially tundra and desert.Furthermore, we showed that one ESM (i.e., CESM) has improved its τ soil estimatemore » by incorporation of the soil vertical profile. These findings indicate that the spatial variation of τ soil is a useful benchmark for ESMs, and we recommend more observations and modeling efforts on soil C dynamics in regions limited by temperature and moisture.« less

Authors:
ORCiD logo [1];  [1]; ORCiD logo [1];  [1];  [1];  [2];  [3];  [4]; ORCiD logo [5]; ORCiD logo [6];  [7];  [8]
  1. East China Normal University, Shanghai (China)
  2. Laboratoire des Sciences du Climat et de l'Environnement (France)
  3. Northern Arizona Univ., Flagstaff, AZ (United States)
  4. Nanjing Forestry University (China)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. CSIRO Ocean and Atmosphere, Victoria (Australia)
  7. Chinese Academy of Sciences, Wuhan (China)
  8. Northern Arizona Univ., Flagstaff, AZ (United States); Tsinghua Univ., Beijing (China)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1502524
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Biogeosciences (Online)
Additional Journal Information:
Journal Name: Biogeosciences (Online); Journal Volume: 16; Journal Issue: 4; Journal ID: ISSN 1726-4189
Publisher:
European Geosciences Union
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Wang, Jing, Xia, Jianyang, Zhou, Xuhui, Huang, Kun, Zhou, Jian, Huang, Yuanyuan, Jiang, Lifen, Xu, Xia, Liang, Junyi, Wang, Ying-Ping, Cheng, Xiaoli, and Luo, Yiqi. Evaluating the simulated mean soil carbon transit times by Earth system models using observations. United States: N. p., 2019. Web. doi:10.5194/bg-16-917-2019.
Wang, Jing, Xia, Jianyang, Zhou, Xuhui, Huang, Kun, Zhou, Jian, Huang, Yuanyuan, Jiang, Lifen, Xu, Xia, Liang, Junyi, Wang, Ying-Ping, Cheng, Xiaoli, & Luo, Yiqi. Evaluating the simulated mean soil carbon transit times by Earth system models using observations. United States. doi:10.5194/bg-16-917-2019.
Wang, Jing, Xia, Jianyang, Zhou, Xuhui, Huang, Kun, Zhou, Jian, Huang, Yuanyuan, Jiang, Lifen, Xu, Xia, Liang, Junyi, Wang, Ying-Ping, Cheng, Xiaoli, and Luo, Yiqi. Wed . "Evaluating the simulated mean soil carbon transit times by Earth system models using observations". United States. doi:10.5194/bg-16-917-2019. https://www.osti.gov/servlets/purl/1502524.
@article{osti_1502524,
title = {Evaluating the simulated mean soil carbon transit times by Earth system models using observations},
author = {Wang, Jing and Xia, Jianyang and Zhou, Xuhui and Huang, Kun and Zhou, Jian and Huang, Yuanyuan and Jiang, Lifen and Xu, Xia and Liang, Junyi and Wang, Ying-Ping and Cheng, Xiaoli and Luo, Yiqi},
abstractNote = {One known bias in current Earth system models (ESMs) is the underestimation of global mean soil carbon (C) transit time (τsoil), which quantifies the age of the C atoms at the time they leave the soil. However, it remains unclear where such underestimations are located globally. Here, we constructed a global database of measured τsoil across 187 sites to evaluate results from 12 ESMs. The observations showed that the estimated τsoil was dramatically shorter from the soil incubation studies in the laboratory environment (median = 4 years; interquartile range = 1 to 25 years) than that derived from field in situ measurements (31; 5 to 84 years) with shifts in stable isotopic C(13C) or the stock-over-flux approach. In comparison with the field observations, the multi-model ensemble simulated a shorter median (19 years) anda smaller spatial variation (6 to 29 years) of τsoil across the same site locations. We then found a significant and negative linear correlation between the in situ measured τsoil and mean annual air temperature. The underestimations of modeled τsoil are mainly located in cold and dry biomes, especially tundra and desert.Furthermore, we showed that one ESM (i.e., CESM) has improved its τsoil estimate by incorporation of the soil vertical profile. These findings indicate that the spatial variation of τsoil is a useful benchmark for ESMs, and we recommend more observations and modeling efforts on soil C dynamics in regions limited by temperature and moisture.},
doi = {10.5194/bg-16-917-2019},
journal = {Biogeosciences (Online)},
number = 4,
volume = 16,
place = {United States},
year = {2019},
month = {2}
}

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