Author: "Deborah N. Huntzinger" / Topic: atmospheric sciences - Searchworks@Jio Institute Digital Library Search Results

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1. Linking global terrestrial CO2 fluxes and environmental drivers: inferences from the Orbiting Carbon Observatory 2 satellite and terrestrial biospheric models

Author: Atul K. Jain, Joe R. Melton, Etsushi Kato, Deborah N. Huntzinger, Junjie Liu, Vladislav Bastrikov, Zichong Chen, Patrick C. McGuire, Sebastian Lienert, Vanessa Haverd, Pierre Friedlingstein, Scot M. Miller, Daven K. Henze, Julia E. M. S. Nabel, Emilie Joetzjer, Benjamin Poulter, Daniel S. Goll, Danica Lombardozzi, Sönke Zaehle, Kelley C. Wells, Hanqin Tian, Andy Wiltshire, and Stephen Sitch
Subjects: 0106 biological sciences, Atmospheric Science, 010504 meteorology & atmospheric sciences, 010604 marine biology & hydrobiology, Biome, Biosphere, Contrast (statistics), 15. Life on land, Atmospheric sciences, 01 natural sciences, Carbon cycle, 13. Climate action, Photosynthetically active radiation, Observatory, Environmental science, Satellite, Precipitation, 0105 earth and related environmental sciences
Abstract: Observations from the Orbiting Carbon Observatory 2 (OCO-2) satellite have been used to estimate CO2 fluxes in many regions of the globe and provide new insight into the global carbon cycle. The objective of this study is to infer the relationships between patterns in OCO-2 observations and environmental drivers (e.g., temperature, precipitation) and therefore inform a process understanding of carbon fluxes using OCO-2. We use a multiple regression and inverse model, and the regression coefficients quantify the relationships between observations from OCO-2 and environmental driver datasets within individual years for 2015–2018 and within seven global biomes. We subsequently compare these inferences to the relationships estimated from 15 terrestrial biosphere models (TBMs) that participated in the TRENDY model inter-comparison. Using OCO-2, we are able to quantify only a limited number of relationships between patterns in atmospheric CO2 observations and patterns in environmental driver datasets (i.e., 10 out of the 42 relationships examined). We further find that the ensemble of TBMs exhibits a large spread in the relationships with these key environmental driver datasets. The largest uncertainty in the models is in the relationship with precipitation, particularly in the tropics, with smaller uncertainties for temperature and photosynthetically active radiation (PAR). Using observations from OCO-2, we find that precipitation is associated with increased CO2 uptake in all tropical biomes, a result that agrees with half of the TBMs. By contrast, the relationships that we infer from OCO-2 for temperature and PAR are similar to the ensemble mean of the TBMs, though the results differ from many individual TBMs. These results point to the limitations of current space-based observations for inferring environmental relationships but also indicate the potential to help inform key relationships that are very uncertain in state-of-the-art TBMs.
Published: 2021
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2. Impacts of land use change and elevated CO2 on the interannual variations and seasonal cycles of gross primary productivity in China

Author: Daniel J. Hayes, Binghao Jia, Kevin Schaefer, Ximing Cai, Hanqin Tian, Akihiko Ito, Yaxing Wei, Xin Luo, Jiafu Mao, Benjamin Poulter, Deborah N. Huntzinger, Atul K. Jain, Xiaoying Shi, Ning Zeng, and Zhenghui Xie
Subjects: Land use, medicine, General Earth and Planetary Sciences, Climate change, Environmental science, Biosphere, Land use, land-use change and forestry, Land cover, Vegetation, Radiative forcing, Seasonality, Atmospheric sciences, medicine.disease
Abstract: Climate change, rising CO2 concentration, and land use and land cover change (LULCC) are primary driving forces for terrestrial gross primary productivity (GPP), but their impacts on the temporal changes in GPP are uncertain. In this study, the effects of the three main factors on the interannual variation (IAV) and seasonal cycle amplitude (SCA) of GPP in China were investigated using 12 terrestrial biosphere models from the Multi-scale Synthesis and Terrestrial Model Intercomparison Project. The simulated ensemble mean value of China's GPP between 1981 and 2010, driven by common climate forcing, LULCC and CO2 data, was found to be 7.4±1.8 Pg C yr−1. In general, climate was the dominant control factor of the annual trends, IAV and seasonality of China's GPP. The overall rising CO2 led to enhanced plant photosynthesis, thus increasing annual mean and IAV of China's total GPP, especially in northeastern and southern China, where vegetation is dense. LULCC decreased the IAV of China's total GPP by ∼7 %, whereas rising CO2 induced an increase of 8 %. Compared to climate change and elevated CO2, LULCC showed less contributions to GPP's temporal variation, and its impact acted locally, mainly in southwestern China. Furthermore, this study also examined subregional contributions to the temporal changes in China's total GPP. Southern and southeastern China showed higher contributions to China's annual GPP, whereas southwestern and central parts of China explained larger fractions of the IAV in China's GPP.
Published: 2020
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3. The Terrestrial Biosphere Model Farm

Author: Joshua B. Fisher, Munish Sikka, Gary L. Block, Christopher R. Schwalm, Nicholas C. Parazoo, Hannah R. Kolus, Malen Sok, Audrey Wang, Anna Gagne‐Landmann, Shakirudeen Lawal, Alexandre Guillaume, Alyssa Poletti, Kevin M. Schaefer, Bassil El Masri, Peter E. Levy, Yaxing Wei, Michael C. Dietze, and Deborah N. Huntzinger
Subjects: Global and Planetary Change, PEcAn, model intercomparison project, land surface model, ecosystem model, ecoinformatic, Ecology and Environment, terrestrial biosphere model, vegetation model, Atmospheric Sciences, Climate Action, Earth System Model, General Earth and Planetary Sciences, Environmental Chemistry
Abstract: Model Intercomparison Projects (MIPs) are fundamental to our understanding of how the land surface responds to changes in climate. However, MIPs are challenging to conduct, requiring the organization of multiple, decentralized modeling teams throughout the world running common protocols. We explored centralizing these models on a single supercomputing system. We ran nine offline terrestrial biosphere models through the Terrestrial Biosphere Model Farm: CABLE, CENTURY, HyLand, ISAM, JULES, LPJ-GUESS, ORCHIDEE, SiB-3, and SiB-CASA. All models were wrapped in a software framework driven with common forcing data, spin-up, and run protocols specified by the Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP) for years 1901-2100. We ran more than a dozen model experiments. We identify three major benefits and three major challenges. The benefits include: (a) processing multiple models through a MIP is relatively straightforward, (b) MIP protocols are run consistently across models, which may reduce some model output variability, and (c) unique multimodel experiments can provide novel output for analysis. The challenges are: (a) technological demand is large, particularly for data and output storage and transfer; (b) model versions lag those from the core model development teams; and (c) there is still a need for intellectual input from the core model development teams for insight into model results. A merger with the open-source, cloud-based Predictive Ecosystem Analyzer (PEcAn) ecoinformatics system may be a path forward to overcoming these challenges.
Published: 2022

4. Five years of variability in the global carbon cycle: comparing an estimate from the Orbiting Carbon Observatory-2 and process-based models

Author: Daniel S. Goll, Xuhui Wang, Vanessa Haverd, Stephen Sitch, Scot M. Miller, Julia E. M. S. Nabel, Sönke Zaehle, Emilie Joetzjer, Benjamin Poulter, Sebastian Lienert, Andy Wiltshire, Vladislav Bastrikov, Danica Lombardozzi, Julia Pongratz, Atul K. Jain, Shilong Piao, Joe R. Melton, Hanqin Tian, Etsushi Kato, Deborah N. Huntzinger, Zichong Chen, Junjie Liu, Peter Anthoni, Pierre Friedlingstein, Patrick C. McGuire, A. Arneth, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)
Subjects: Biosphere model, 010504 meteorology & atmospheric sciences, 530 Physics, Biome, OCO-2 satellite, Magnitude (mathematics), Tropical and subtropical grasslands, savannas, and shrublands, 010501 environmental sciences, Atmospheric sciences, 01 natural sciences, Carbon cycle, inter-annual variability, 550 Earth sciences & geology, carbon cycle, ddc:550, climate-carbon relationships, Precipitation, 0105 earth and related environmental sciences, General Environmental Science, Renewable Energy, Sustainability and the Environment, Public Health, Environmental and Occupational Health, Tropics, 15. Life on land, Earth sciences, 13. Climate action, [SDU]Sciences of the Universe [physics], Environmental science, environmental drivers, Satellite, ddc:500
Abstract: Year-to-year variability in CO2 fluxes can yield insight into climate-carbon cycle relationships, a fundamental yet uncertain aspect of the terrestrial carbon cycle. In this study, we use global observations from NASA’s Orbiting Carbon Observatory-2 (OCO-2) satellite for years 2015–2019 and a geostatistical inverse model to evaluate 5 years of interannual variability (IAV) in CO2 fluxes and its relationships with environmental drivers. OCO-2 launched in late 2014, and we specifically evaluate IAV during the time period when OCO-2 observations are available. We then compare inferences from OCO-2 with state-of-the-art process-based models (terrestrial biosphere model, TBMs). Results from OCO-2 suggest that the tropical grasslands biome (including grasslands, savanna, and agricultural lands within the tropics) makes contributions to global IAV during the 5 year study period that are comparable to tropical forests, a result that differs from a majority of TBMs. Furthermore, existing studies disagree on the environmental variables that drive IAV during this time period, and the analysis using OCO-2 suggests that both temperature and precipitation make comparable contributions. TBMs, by contrast, tend to estimate larger IAV during this time and usually estimate larger relative contributions from the extra-tropics. With that said, TBMs show little consensus on both the magnitude and the contributions of different regions to IAV. We further find that TBMs show a wide range of responses on the relationships of CO2 fluxes with annual anomalies in temperature and precipitation, and these relationships across most of the TBMs have a larger magnitude than inferred from OCO-2. Overall, the findings of this study highlight large uncertainties in process-based estimates of IAV during recent years and provide an avenue for evaluating these processes against inferences from OCO-2.
Published: 2021
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5. Large‐Scale Reductions in Terrestrial Carbon Uptake Following Central Pacific El Niño

Author: David J. P. Moore, Yulong Zhang, Deborah N. Huntzinger, William K. Smith, Conghe Song, and Matthew P. Dannenberg
Subjects: Geophysics, El Niño Southern Oscillation, El Niño, Scale (ratio), Carbon uptake, General Earth and Planetary Sciences, Environmental science, Arid ecosystems, Atmospheric sciences, Carbon cycle
Published: 2021
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6. Linking global terrestrial CO2 fluxes and environmental drivers using OCO-2 and a geostatistical inverse model

Author: Deborah N. Huntzinger, Zichong Chen, Junjie Liu, Daven K. Henze, Kelley C. Wells, and Scot M. Miller
Subjects: Flux (metallurgy), 010504 meteorology & atmospheric sciences, Photosynthetically active radiation, Biome, Environmental science, Satellite, Precipitation, Atmospheric model, Atmospheric sciences, 01 natural sciences, 0105 earth and related environmental sciences, Carbon cycle, Latitude
Abstract: Observations from the OCO-2 satellite, launched in July 2014, have been used to estimate CO2 fluxes in many regions of the globe and provide new insight on the global carbon cycle. A challenge now is to not only estimate fluxes using satellite observations but also to understand how these fluxes are connected to variations in environmental conditions. In this study, we specifically evaluate the capabilities and limitations of utilizing current OCO-2 observations to infer connections between CO2 fluxes and underlying environmental variables. To do so, we adapt geostatistical inverse modeling to satellite-based applications and evaluate a case study for year 2016 using OCO-2. One unique aspect of the geostatistical approach is that we can use estimates of environmental and meteorological variables to help estimate CO2 fluxes in place of a traditional prior flux model. We are able to quantify the relationships between CO2 fluxes and a few environmental variables across global biomes; we find that a simple combination of air temperature, daily precipitation, and photosynthetically active radiation (PAR) can describe almost 90 % of the variability in CO2 fluxes as seen through OCO-2 observations. PAR is an adept predictor of fluxes across mid-to-high latitudes, whereas a combined set of air temperature and precipitation shows strong explanatory power across tropical biomes. However, we are unable to quantify relationships with additional environmental variables because many variables are correlated or colinear when passed through an atmospheric model and averaged across a total atmospheric column. Overall, we estimate a global net biospheric flux of −1.73 ± 0.53 GtC in year 2016, in close agreement with recent inverse modeling studies using OCO-2 retrievals as observational constraints.
Published: 2020
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7. Enhanced peak growth of global vegetation and its key mechanisms

Author: Yiqi Luo, Kun Huang, Kevin Schaefer, Yang Qiao, Robert B. Cook, Chenyu Bian, Joshua B. Fisher, Xiaoni Xu, Liming Yan, Anders Ahlström, Jiquan Chen, Ying-Ping Wang, Anna M. Michalak, Deborah N. Huntzinger, Jing Wang, Yuanyuan Fang, Jianyang Xia, Zhao Li, Christopher R. Schwalm, Yaxing Wei, and Erqian Cui
Subjects: 0106 biological sciences, 010504 meteorology & atmospheric sciences, Ecology, Plant Development, Biosphere, Seasonality, Atmospheric sciences, medicine.disease, 010603 evolutionary biology, 01 natural sciences, Photosynthetic capacity, Normalized Difference Vegetation Index, Remote Sensing Technology, medicine, Environmental science, Terrestrial ecosystem, Ecosystem, Seasons, Photosynthesis, medicine.symptom, Ecosystem ecology, Vegetation (pathology), Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences
Abstract: The annual peak growth of vegetation is critical in characterizing the capacity of terrestrial ecosystem productivity and shaping the seasonality of atmospheric CO2 concentrations. The recent greening of global lands suggests an increasing trend of terrestrial vegetation growth, but whether or not the peak growth has been globally enhanced still remains unclear. Here, we use two global datasets of gross primary productivity (GPP) and a satellite-derived Normalized Difference Vegetation Index (NDVI) to characterize recent changes in annual peak vegetation growth (that is, GPPmax and NDVImax). We demonstrate that the peak in the growth of global vegetation has been linearly increasing during the past three decades. About 65% of the NDVImax variation is evenly explained by expanding croplands (21%), rising CO2 (22%) and intensifying nitrogen deposition (22%). The contribution of expanding croplands to the peak growth trend is substantiated by measurements from eddy-flux towers, sun-induced chlorophyll fluorescence and a global database of plant traits, all of which demonstrate that croplands have a higher photosynthetic capacity than other vegetation types. The large contribution of CO2 is also supported by a meta-analysis of 466 manipulative experiments and 15 terrestrial biosphere models. Furthermore, we show that the contribution of GPPmax to the change in annual GPP is less in the tropics than in other regions. These multiple lines of evidence reveal an increasing trend in the peak growth of global vegetation. The findings highlight the important roles of agricultural intensification and atmospheric changes in reshaping the seasonality of global vegetation growth.
Published: 2018
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8. Exploring the environmental drivers of global terrestrial CO2 fluxes inferred from OCO-2 and a geostatistical inverse model

Author: Junjie Liu, Scot M. Miller, Deborah N. Huntzinger, Zichong Chen, Kelley C. Wells, and Daven K. Henze
Subjects: Environmental science, Inverse, Sensitivity (control systems), Biogeosciences, Atmospheric sciences, Carbon cycle, Term (time)
Abstract: The carbon cycle displays strong sensitivity to short term variations in environmental conditions, and it is key to understand how these variations are linked with variations in CO2 fluxes. Previou...
Published: 2020
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9. Field-experiment constraints on the enhancement of the terrestrial carbon sink by CO2 fertilization

Author: Yuanyuan Fang, Ning Zeng, Xiaoying Shi, Trevor F. Keenan, Akihiko Ito, Philippe Ciais, Kai Wang, Shilong Piao, M. A. Arain, Qiuan Zhu, Mengtian Huang, Tao Wang, Jian Song, Joshua B. Fisher, Anna M. Michalak, Josep Peñuelas, Changhui Peng, Atul K. Jain, Chris Huntingford, Deborah N. Huntzinger, Yongwen Liu, Jiafu Mao, Yaxing Wei, Thomas Gasser, Hanqin Tian, Ivan A. Janssens, Maoyi Huang, Shiqiang Wan, Christopher R. Schwalm, Hui Yang, Xuhui Wang, Benjamin Poulter, Han Wang, Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University [Beijing], International Institute for Applied Systems Analysis [Laxenburg] (IIASA), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), ICOS-ATC (ICOS-ATC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Henan University, Institut National des Langues et Civilisations Orientales (Inalco), The Center for Applied Genomics, Children’s Hospital of Philadelphia (CHOP ), Department of Biology, University of Antwerp (UA), Centre de Recerca Ecològica i Aplicacions Forestals (CREAF), Centre for Ecology and Hydrology [Wallingford] (CEH), Natural Environment Research Council (NERC), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Department of Chemistry [University of Houston], University of Houston, University of Oxford, Northern Arizona University [Flagstaff], National Institute for Environmental Studies (NIES), Department of Atmospheric Sciences [Urbana], University of Illinois at Urbana-Champaign [Urbana], University of Illinois System-University of Illinois System, Environmental Sciences Division [Oak Ridge], Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC-UT-Battelle, LLC, Carnegie Observatories, Carnegie Institution for Science, Université du Québec à Trois-Rivières (UQTR), NASA Goddard Space Flight Center (GSFC), Graduate School of Geography, Clark University, Shandong Agricultural University (SDAU), Northwest A and F University, Laboratoire de Chimie - UMR5182 (LC), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Henan University, Kaifeng (HENU), Henan University, Kaifeng, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), University of Oxford [Oxford], Carnegie Institution for Science [Washington], Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon)-Institut de Chimie du CNRS (INC)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010504 meteorology & atmospheric sciences, Life on Land, Field experiment, Physics, Northern Hemisphere, Carbon sink, 15. Life on land, Carbon sequestration, 010502 geochemistry & geophysics, Atmospheric sciences, 01 natural sciences, Arctic, 13. Climate action, Temperate climate, General Earth and Planetary Sciences, Environmental science, Meteorology & Atmospheric Sciences, Terrestrial ecosystem, Ecosystem, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract: Clarifying how increased atmospheric CO2 concentration (eCO2) contributes to accelerated land carbon sequestration remains important since this process is the largest negative feedback in the coupled carbon–climate system. Here, we constrain the sensitivity of the terrestrial carbon sink to eCO2 over the temperate Northern Hemisphere for the past five decades, using 12 terrestrial ecosystem models and data from seven CO2 enrichment experiments. This constraint uses the heuristic finding that the northern temperate carbon sink sensitivity to eCO2 is linearly related to the site-scale sensitivity across the models. The emerging data-constrained eCO2 sensitivity is 0.64 ± 0.28 PgC yr−1 per hundred ppm of eCO2. Extrapolating worldwide, this northern temperate sensitivity projects the global terrestrial carbon sink to increase by 3.5 ± 1.9 PgC yr−1 for an increase in CO2 of 100 ppm. This value suggests that CO2 fertilization alone explains most of the observed increase in global land carbon sink since the 1960s. More CO2 enrichment experiments, particularly in boreal, arctic and tropical ecosystems, are required to explain further the responsible processes. The northern temperate carbon sink is estimated to increase by 0.64 PgC each year for each increase in atmospheric CO2 concentrations by 100 ppm, suggests an analysis of data from field experiments at 7 sites constraints.
Published: 2019
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10. Global vegetation biomass production efficiency constrained by models and observations

Author: Anna M. Michalak, Changhui Peng, Yuanyuan Fang, Daniel J. Hayes, Dahe Qin, Kai Wang, Atul K. Jain, Yongwen Liu, Campioli Matteo, Akihiko Ito, Philippe Ciais, Sara Vicca, Josep Peñuelas, Daniel S. Goll, M. Altaf Arain, Deborah N. Huntzinger, Jiafu Mao, Xiaoying Shi, Qiuan Zhu, Yaxing Wei, Christopher R. Schwalm, Ivan A. Janssens, Kevin Schaefer, Benjamin Poulter, Xiangyi Li, Shushi Peng, Joshua B. Fisher, Yue He, Daniel M. Ricciuto, Hanqin Tian, Ning Zeng, University of California [San Francisco] (UCSF), University of California, Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University [Beijing], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-ATC (ICOS-ATC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), School of Geography and earth sciences, McMaster University [Hamilton, Ontario], Department of Chemistry [University of Houston], University of Houston, University of Oxford [Oxford], Cyprus Oceanography Center, University of Cyprus (UCY), Northern Arizona University [Flagstaff], National Institute for Environmental Studies (NIES), Department of Atmospheric Sciences [Urbana], University of Illinois at Urbana-Champaign [Urbana], University of Illinois System-University of Illinois System, Department of Biology, University of Antwerp (UA), Environmental Sciences Division [Oak Ridge], Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC-UT-Battelle, LLC, Carnegie Observatories, Carnegie Institution for Science [Washington], Université du Québec à Trois-Rivières (UQTR), Centre de Recerca Ecològica i Aplicacions Forestals (CREAF), Montana State University (MSU), Graduate School of Geography, Clark University, Shandong Agricultural University (SDAU), Department of Biology, Centre of Excellence PLECO (Plant and Vegetation Ecology), Northwest A and F University, University of California [San Francisco] (UC San Francisco), University of California (UC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), University of Oxford, University of Cyprus [Nicosia] (UCY), and Carnegie Institution for Science
Subjects: 0106 biological sciences, Carbon Sequestration, 010504 meteorology & atmospheric sciences, chemistry.chemical_element, Photosynthesis, Atmospheric sciences, 010603 evolutionary biology, 01 natural sciences, Carbon cycle, Carbon Cycle, Trees, Environmental Chemistry, Compounds of carbon, Ecosystem, Biomass, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Biology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science, chemistry.chemical_classification, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Biomass (ecology), Ecology, Carbon sink, Primary production, 15. Life on land, Carbon Dioxide, Carbon, Chemistry, chemistry, 13. Climate action, Environmental science
Abstract: Plants use only a fraction of their photosynthetically derived carbon for biomass production (BP). The biomass production efficiency (BPE), defined as the ratio of BP to photosynthesis, and its variation across and within vegetation types is poorly understood, which hinders our capacity to accurately estimate carbon turnover times and carbon sinks. Here, we present a new global estimation of BPE obtained by combining field measurements from 113 sites with 14 carbon cycle models. Our best estimate of global BPE is 0.41 +/- 0.05, excluding cropland. The largest BPE is found in boreal forests (0.48 +/- 0.06) and the lowest in tropical forests (0.40 +/- 0.04). Carbon cycle models overestimate BPE, although models with carbon-nitrogen interactions tend to be more realistic. Using observation-based estimates of global photosynthesis, we quantify the global BP of non-cropland ecosystems of 41 +/- 6 Pg C/year. This flux is less than net primary production as it does not contain carbon allocated to symbionts, used for exudates or volatile carbon compound emissions to the atmosphere. Our study reveals a positive bias of 24 +/- 11% in the model-estimated BP (10 of 14 models). When correcting models for this bias while leaving modeled carbon turnover times unchanged, we found that the global ecosystem carbon storage change during the last century is decreased by 67% (or 58 Pg C).
Published: 2019
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11. Land carbon models underestimate the severity and duration of drought’s impact on plant productivity

Author: Yaxing Wei, Nicholas P. McKay, Benjamin Poulter, Deborah N. Huntzinger, Nicholas C. Parazoo, Anna M. Michalak, Yuanyuan Fang, Xiaoying Shi, Jiafu Mao, Kevin Schaefer, Christopher R. Schwalm, Joshua B. Fisher, and Hannah Rose Kolus
Subjects: 0301 basic medicine, Life on Land, Climate Change, Lag, lcsh:Medicine, Climate change, Atmospheric sciences, Article, Carbon Cycle, Trees, Carbon cycle, 03 medical and health sciences, 0302 clinical medicine, Theoretical, Models, Drought recovery, Ecosystem, lcsh:Science, Multidisciplinary, lcsh:R, Carbon sink, Primary production, Vegetation, Carbon Dioxide, Models, Theoretical, Droughts, Climate Action, 030104 developmental biology, Environmental science, lcsh:Q, 030217 neurology & neurosurgery
Abstract: The ability to accurately predict ecosystem drought response and recovery is necessary to produce reliable forecasts of land carbon uptake and future climate. Using a suite of models from the Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP), we assessed modeled net primary productivity (NPP) response to, and recovery from, drought events against a benchmark derived from tree ring observations between 1948 and 2008 across forested regions of the US and Europe. We find short lag times (0–6 months) between climate anomalies and modeled NPP response. Although models accurately simulate the direction of drought legacy effects (i.e. NPP decreases), projected effects are approximately four times shorter and four times weaker than observations suggest. This discrepancy between observed and simulated vegetation recovery from drought reveals a potential critical model deficiency. Since productivity is a crucial component of the land carbon balance, models that underestimate drought recovery time could overestimate predictions of future land carbon sink strength and, consequently, underestimate forecasts of atmospheric CO2.
Published: 2019
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12. Accelerating rates of Arctic carbon cycling revealed by long-term atmospheric CO 2 measurements

Author: Colm Sweeney, Su-Jong Jeong, Anna M. Michalak, A. Anthony Bloom, Nicholas C. Parazoo, Chunmiao Zheng, Gabriela Schaepman-Strub, David Medvigy, Deborah N. Huntzinger, Christopher R. Schwalm, Charles E. Miller, and David S. Schimel
Subjects: 0106 biological sciences, Multidisciplinary, 010504 meteorology & atmospheric sciences, Growing season, chemistry.chemical_element, Permafrost, Atmospheric sciences, 010603 evolutionary biology, 01 natural sciences, Tundra, Carbon cycle, Arctic, chemistry, Respiration, Ecosystem, Carbon, 0105 earth and related environmental sciences
Abstract: The contemporary Arctic carbon balance is uncertain, and the potential for a permafrost carbon feedback of anywhere from 50 to 200 petagrams of carbon (Schuur et al., 2015) compromises accurate 21st-century global climate system projections. The 42-year record of atmospheric CO2 measurements at Barrow, Alaska (71.29 N, 156.79 W), reveals significant trends in regional land-surface CO2 anomalies (ΔCO2), indicating long-term changes in seasonal carbon uptake and respiration. Using a carbon balance model constrained by ΔCO2, we find a 13.4% decrease in mean carbon residence time (50% confidence range = 9.2 to 17.6%) in North Slope tundra ecosystems during the past four decades, suggesting a transition toward a boreal carbon cycling regime. Temperature dependencies of respiration and carbon uptake suggest that increases in cold season Arctic labile carbon release will likely continue to exceed increases in net growing season carbon uptake under continued warming trends.
Published: 2018
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13. How well do terrestrial biosphere models simulate coarse-scale runoff in the contiguous United States?

Author: Deborah N. Huntzinger, Christopher R. Schwalm, Ge Sun, Robert B. Cook, Benjamin Poulter, Ning Zeng, Peter V. Caldwell, Hanqin Tian, Ian Baker, Yaxing Wei, and Ronald P. Neilson
Subjects: Current (stream), Ecological Modelling, Scale (ratio), Environmental change, Ecology, Ecological Modeling, Environmental science, Biosphere, Precipitation, Water cycle, Atmospheric sciences, Surface runoff, Stream gauge
Abstract: a b s t r a c t Significant changes in the water cycle are expected under current global environmental change. Robust assessment of present-day water cycle dynamics at continental to global scales is confounded by short- comings in the observed record. Modeled assessments also yield conflicting results which are linked to differences in model structure and simulation protocol. Here we compare simulated gridded (1 ◦ spatial resolution) runoff from six terrestrial biosphere models (TBMs), seven reanalysis products, and one grid- ded surface station product in the contiguous United States (CONUS) from 2001 to 2005. We evaluate the consistency of these 14 estimates with stream gauge data, both as depleted flow and corrected for net withdrawals (2005 only), at the CONUS and water resource region scale, as well as examining similarity across TBMs and reanalysis products at the grid cell scale. Mean runoff across all simulated products and regions varies widely (range: 71 to 356 mm yr −1 ) relative to observed continental-scale runoff (209 or 280 mm yr −1
Published: 2015
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14. Response of Water Use Efficiency to Global Environmental Change Based on Output From Terrestrial Biosphere Models

Author: Xiaoying Shi, Akihiko Ito, Philippe Ciais, Jiafu Mao, Weile Wang, Benjamin Poulter, Yaxing Wei, Anna M. Michalak, Daniel M. Ricciuto, Atul K. Jain, Sha Zhou, Deborah N. Huntzinger, Shuli Niu, Christopher R. Schwalm, Yao Zhang, Guangqian Wang, Yuefei Huang, Joshua B. Fisher, Bofu Yu, Northern Arizona University [Flagstaff], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), ICOS-ATC (ICOS-ATC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), ECE Department, (ECE), University of California [Davis] (UC Davis), University of California (UC)-University of California (UC), University of Oxford, Carnegie Observatories, Carnegie Institution for Science, Montana State University (MSU), Synth Res Ctr Chinese Ecosyst Res Network, Institute of Geographic Sciences and Natural Resources Research, Climate Change Science Institute [Oak Ridge] (CCSI), Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC-UT-Battelle, LLC, Department of Atmospheric Sciences [Urbana], University of Illinois at Urbana-Champaign [Urbana], University of Illinois System-University of Illinois System, Environmental Sciences Division [Oak Ridge], National Institute for Environmental Studies (NIES), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), University of California-University of California, University of Oxford [Oxford], and Carnegie Institution for Science [Washington]
Subjects: 0106 biological sciences, Atmospheric Science, 010504 meteorology & atmospheric sciences, Vapour Pressure Deficit, interannual variability, Oceanography, 010603 evolutionary biology, 01 natural sciences, Atmospheric Sciences, Evapotranspiration, Environmental Chemistry, Meteorology & Atmospheric Sciences, Ecosystem, structure, Water cycle, Water-use efficiency, Leaf area index, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 0105 earth and related environmental sciences, General Environmental Science, Transpiration, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, atmospheric CO2, Global and Planetary Change, 15. Life on land, attribution, Climate Action, trend, Geochemistry, 13. Climate action, Climatology, physiology, Environmental science, Terrestrial ecosystem
Abstract: Author(s): Zhou, S; Yu, B; Schwalm, CR; Ciais, P; Zhang, Y; Fisher, JB; Michalak, AM; Wang, W; Poulter, B; Huntzinger, DN; Niu, S; Mao, J; Jain, A; Ricciuto, DM; Shi, X; Ito, A; Wei, Y; Huang, Y; Wang, G | Abstract: Water use efficiency (WUE), defined as the ratio of gross primary productivity and evapotranspiration at the ecosystem scale, is a critical variable linking the carbon and water cycles. Incorporating a dependency on vapor pressure deficit, apparent underlying WUE (uWUE) provides a better indicator of how terrestrial ecosystems respond to environmental changes than other WUE formulations. Here we used 20th century simulations from four terrestrial biosphere models to develop a novel variance decomposition method. With this method, we attributed variations in apparent uWUE to both the trend and interannual variation of environmental drivers. The secular increase in atmospheric CO2 explained a clear majority of total variation (66n±n32%: meann±none standard deviation), followed by positive trends in nitrogen deposition and climate, as well as a negative trend in land use change. In contrast, interannual variation was mostly driven by interannual climate variability. To analyze the mechanism of the CO2 effect, we partitioned the apparent uWUE into the transpiration ratio (transpiration over evapotranspiration) and potential uWUE. The relative increase in potential uWUE parallels that of CO2, but this direct CO2 effect was offset by 20n±n4% by changes in ecosystem structure, that is, leaf area index for different vegetation types. However, the decrease in transpiration due to stomatal closure with rising CO2 was reduced by 84% by an increase in leaf area index, resulting in small changes in the transpiration ratio. CO2 concentration thus plays a dominant role in driving apparent uWUE variations over time, but its role differs for the two constituent components: potential uWUE and transpiration.
Published: 2017
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15. Impact of large-scale climate extremes on biospheric carbon fluxes: An intercomparison based on MsTMIP data

Author: Weile Wang, Markus Reichstein, Daniel M. Ricciuto, Bassil El-Masri, Ning Zeng, Huimin Lei, Shushi Peng, Hanqin Tian, Atul K. Jain, Robert B. Cook, Xiaoying Shi, Bo Tao, Anna M. Michalak, Gwenaëlle Berthier, Nicolas Viovy, Chaoqun Lu, Miguel D. Mahecha, Akihiko Ito, Philippe Ciais, Anthony W. King, Maoyi Huang, Yaxing Wei, Christopher R. Schwalm, Jiafu Mao, Benjamin Poulter, Jia Yang, Jakob Zscheischler, Deborah N. Huntzinger, Max Planck Institute for Biogeochemistry (MPI-BGC), Max-Planck-Gesellschaft, Carnegie Institution for Science [Washington], Northern Arizona University [Flagstaff], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-ATC (ICOS-ATC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC, University of Illinois at Urbana-Champaign [Urbana], University of Illinois System, Pacific Northwest National Laboratory (PNNL), National Institute for Environmental Studies (NIES), Department of Atmospheric Sciences [Urbana], University of Illinois System-University of Illinois System, Tsinghua University [Beijing] (THU), Auburn University (AU), Environmental Sciences Division [Oak Ridge], UT-Battelle, LLC-UT-Battelle, LLC, Peking University [Beijing], Modélisation des Surfaces et Interfaces Continentales (MOSAIC), NASA, University of Maryland [College Park], University of Maryland System, Carnegie Institution for Science, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Atmospheric Science, Global and Planetary Change, Taiga, Primary production, chemistry.chemical_element, 15. Life on land, Radiative forcing, Atmospheric sciences, Earth system science, Flux (metallurgy), chemistry, 13. Climate action, Climatology, Environmental Chemistry, Environmental science, Precipitation, Scale (map), [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Carbon, General Environmental Science
Abstract: International audience; Understanding the role of climate extremes and their impact on the carbon (C) cycle is increasingly a focus of Earth system science. Climate extremes such as droughts, heat waves, or heavy precipitation events can cause substantial changes in terrestrial C fluxes. On the other hand, extreme changes in C fluxes are often, but not always, driven by extreme climate conditions. Here we present an analysis of how extremes in temperature and precipitation, and extreme changes in terrestrial C fluxes are related to each other in 10 state-of-the-art terrestrial carbon models, all driven by the same climate forcing. We use model outputs from the North American Carbon Program Multi-scale Synthesis and Terrestrial Model Intercomparison Project (MsTMIP). A global-scale analysis shows that both droughts and heat waves translate into anomalous net releases of CO 2 from the land surface via different mechanisms: Droughts largely decrease gross primary production (GPP) and to a lower extent total respiration (TR), while heat waves slightly decrease GPP but increase TR. Cold and wet periods have a smaller opposite effect. Analyzing extremes in C fluxes reveals that extreme changes in GPP and TR are often caused by strong shifts in water availability, but for extremes in TR shifts in temperature are also important. Extremes in net CO 2 exchange are equally strongly driven by deviations in temperature and precipitation. Models mostly agree on the sign of the C flux response to climate extremes, but model spread is large. In tropical forests, C cycle extremes are driven by water availability, whereas in boreal forests temperature plays a more important role. Models are particularly uncertain about the C flux response to extreme heat in boreal forests.
Published: 2014
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16. The North American Carbon Program Multi-Scale Synthesis and Terrestrial Model Intercomparison Project – Part 1: Overview and experimental design

Author: Xiaoying Shi, Deborah N. Huntzinger, Shuguang Liu, Ning Zeng, Weile Wang, Benjamin Poulter, G. Berthier, Shushi Peng, Yaxing Wei, Christopher R. Schwalm, Fang Zhao, Kevin Schaefer, Andrew R. Jacobson, Robert B. Cook, Wilfred M. Post, Jiafu Mao, D. Riccuito, Maoyi Huang, Anna M. Michalak, Chaoqun Lu, Changhui Peng, Daniel J. Hayes, Huimin Lei, Akihiko Ito, Hanqin Tian, Anthony W. King, Qiuan Zhu, Northern Arizona University [Flagstaff], Carnegie Institution for Science [Washington], National Snow and Ice Data Center (NSIDC), University of Colorado [Boulder], Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Pacific Northwest National Laboratory (PNNL), National Institute for Environmental Studies (NIES), Auburn University (AU), Université du Québec à Montréal = University of Québec in Montréal (UQAM), Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), National Aeronautics and Space Administration, Partenaires INRAE, Department of Atmospheric and Oceanic Science [College Park] (AOSC), University of Maryland [College Park], University of Maryland System-University of Maryland System, Northwest A and F University, Carnegie Institution for Science, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and National Aeronautics and Space Administration (NASA)
Subjects: 0106 biological sciences, Nutrient cycle, 010504 meteorology & atmospheric sciences, Meteorology, Scale (ratio), Biomass, chemistry.chemical_element, 010501 environmental sciences, Atmospheric sciences, 01 natural sciences, Carbon cycle, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010604 marine biology & hydrobiology, lcsh:QE1-996.5, Biosphere, Soil carbon, Vegetation, 15. Life on land, lcsh:Geology, chemistry, 13. Climate action, Environmental science, Carbon
Abstract: Terrestrial biosphere models (TBMs) have become an integral tool for extrapolating local observations and understanding of land-atmosphere carbon exchange to larger regions. The North American Carbon Program (NACP) Multi-scale synthesis and Terrestrial Model Intercomparison Project (MsTMIP) is a formal model intercomparison and evaluation effort focused on improving the diagnosis and attribution of carbon exchange at regional and global scales. MsTMIP builds upon current and past synthesis activities, and has a unique framework designed to isolate, interpret, and inform understanding of how model structural differences impact estimates of carbon uptake and release. Here we provide an overview of the MsTMIP effort and describe how the MsTMIP experimental design enables the assessment and quantification of TBM structural uncertainty. Model structure refers to the types of processes considered (e.g. nutrient cycling, disturbance, lateral transport of carbon), and how these processes are represented (e.g. photosynthetic formulation, temperature sensitivity, respiration) in the models. By prescribing a common experimental protocol with standard spin-up procedures and driver data sets, we isolate any biases and variability in TBM estimates of regional and global carbon budgets resulting from differences in the models themselves (i.e. model structure) and model-specific parameter values. An initial intercomparison of model structural differences is represented using hierarchical cluster diagrams (a.k.a. dendrograms), which highlight similarities and differences in how models account for carbon cycle, vegetation, energy, and nitrogen cycle dynamics. We show that, despite the standardized protocol used to derive initial conditions, models show a high degree of variation for GPP, total living biomass, and total soil carbon, underscoring the influence of differences in model structure and parameterization on model estimates.
Published: 2013
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17. Uncertainty in the response of terrestrial carbon sink to environmental drivers undermines carbon-climate feedback predictions

Author: Xiaoying Shi, Anna M. Michalak, Nicholas C. Parazoo, Weile Wang, Chaoqun Lu, Akihiko Ito, Daniel J. Hayes, Anthony W. King, Joshua B. Fisher, Christopher R. Schwalm, Benjamin Poulter, Yaxing Wei, Yuanyuan Fang, Kevin Schaefer, Huimin Lei, Atul K. Jain, Robert B. Cook, P. Ciais, Deborah N. Huntzinger, Maoyi Huang, Jiafu Mao, Shushi Peng, Hanqin Tian, Fang Zhao, Daniel M. Ricciuto, Fabienne Maignan, Ning Zeng, Northern Arizona University [Flagstaff], Carnegie Institution for Science, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), ICOS-ATC (ICOS-ATC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC, University of Colorado [Boulder], Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), University of Maine, Pacific Northwest National Laboratory (PNNL), National Institute for Environmental Studies (NIES), University of Illinois at Urbana-Champaign [Urbana], University of Illinois System, Tsinghua University [Beijing] (THU), Department of Ecology, Evolution and Organismal Biology, Iowa State University (ISU), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), Montana State University (MSU), Environmental Sciences Division [Oak Ridge], UT-Battelle, LLC-UT-Battelle, LLC, Auburn University (AU), NASA Ames Research Center (ARC), Department of Atmospheric and Oceanic Science [College Park] (AOSC), University of Maryland [College Park], University of Maryland System-University of Maryland System, Carnegie Institution for Science [Washington], Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and California Institute of Technology (CALTECH)-NASA
Subjects: 010504 meteorology & atmospheric sciences, Life on Land, Science, chemistry.chemical_element, 010501 environmental sciences, Atmospheric sciences, 01 natural sciences, Article, Carbon cycle, Atmosphere, Predictability, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, 0105 earth and related environmental sciences, Multidisciplinary, Ecology, Carbon sink, 15. Life on land, Land area, Climate Action, chemistry, 13. Climate action, [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology, Environmental science, Medicine, Terrestrial ecosystem, Cycling, Carbon
Abstract: Terrestrial ecosystems play a vital role in regulating the accumulation of carbon (C) in the atmosphere. Understanding the factors controlling land C uptake is critical for reducing uncertainties in projections of future climate. The relative importance of changing climate, rising atmospheric CO2, and other factors, however, remains unclear despite decades of research. Here, we use an ensemble of land models to show that models disagree on the primary driver of cumulative C uptake for 85% of vegetated land area. Disagreement is largest in model sensitivity to rising atmospheric CO2 which shows almost twice the variability in cumulative land uptake since 1901 (1 s.d. of 212.8 PgC vs. 138.5 PgC, respectively). We find that variability in CO2 and temperature sensitivity is attributable, in part, to their compensatory effects on C uptake, whereby comparable estimates of C uptake can arise by invoking different sensitivities to key environmental conditions. Conversely, divergent estimates of C uptake can occur despite being based on the same environmental sensitivities. Together, these findings imply an important limitation to the predictability of C cycling and climate under unprecedented environmental conditions. We suggest that the carbon modeling community prioritize a probabilistic multi-model approach to generate more robust C cycle projections.
Published: 2017
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18. North American carbon dioxide sources and sinks: magnitude, attribution, and uncertainty

Author: Wilfred M. Post, Tristam O. West, Anthony W. King, Deborah N. Huntzinger, and Daniel J. Hayes
Subjects: Biomass (ecology), Carbon dioxide in Earth's atmosphere, Ecology, chemistry.chemical_element, Vegetation, Atmospheric sciences, Atmosphere, chemistry.chemical_compound, chemistry, Deforestation, Carbon dioxide, Environmental science, Ecosystem, Carbon, Ecology, Evolution, Behavior and Systematics
Abstract: North America is both a source and sink of atmospheric carbon dioxide (CO2). Continental sources – such as fossil-fuel combustion in the US and deforestation in Mexico – and sinks – including most ecosystems, and particularly secondary forests – add and remove CO2 from the atmosphere, respectively. Photosynthesis converts CO2 into carbon as biomass, which is stored in vegetation, soils, and wood products. However, ecosystem sinks compensate for only ~35% of the continent's fossil-fuel-based CO2 emissions; North America therefore represents a net CO2 source. Estimating the magnitude of ecosystem sinks, even though the calculation is confounded by uncertainty as a result of individual inventory- and model-based alternatives, has improved through the use of a combined approach.
Published: 2012
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19. Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions, and a new approach for estimating net ecosystem exchange from inventory-based data

Author: Daniel J. Hayes, David P. Turner, Brian McConkey, Andrew R. Jacobson, Richard A. Birdsey, G. Stinson, Yude Pan, W. Mac Post, Linda S. Heath, Deborah N. Huntzinger, A. David McGuire, Werner A. Kurz, Robert B. Cook, Bernardus Hendricus jozeph De Jong, Yaxing Wei, and Tristram O. West
Subjects: Hydrology, Global and Planetary Change, Ecology, Carbon sink, Climate change, Biosphere, Atmospheric sciences, Spatial distribution, Carbon cycle, Environmental Chemistry, Environmental science, Ecosystem, Land use, land-use change and forestry, Sink (computing), General Environmental Science
Abstract: We develop an approach for estimating net ecosystem exchange (NEE) using inventory-based information over North America (NA) for a recent 7-year period (ca. 2000–2006). The approach notably retains information on the spatial distribution of NEE, or the vertical exchange between land and atmosphere of all non-fossil fuel sources and sinks of CO2, while accounting for lateral transfers of forest and crop products as well as their eventual emissions. The total NEE estimate of a � 327 ± 252 TgC yr � 1 sink for NA was driven primarily by CO2 uptake in the Forest Lands sector (� 248 TgC yr � 1 ), largely in the Northwest and Southeast regions of the US, and in the Crop Lands sector (� 297 TgC yr � 1 ), predominantly in the Midwest US states. These sinks are counteracted by the carbon source estimated for the Other Lands sector (+218 TgC yr � 1 ), where much of the forest and crop products are assumed to be returned to the atmosphere (through livestock and human consumption). The ecosystems of Mexico are estimated to be a small net source (+18 TgC yr � 1 ) due to land use change between 1993 and 2002. We compare these inventorybased estimates with results from a suite of terrestrial biosphere and atmospheric inversion models, where the mean continental-scale NEE estimate for each ensemble is � 511 TgC yr � 1 and � 931 TgC yr � 1 , respectively. In the modeling approaches, all sectors, including Other Lands, were generally estimated to be a carbon sink, driven in part by assumed CO2 fertilization and/or lack of consideration of carbon sources from disturbances and product emissions. Additional fluxes not measured by the inventories, although highly uncertain, could add an additional � 239 TgC yr � 1 to the inventory-based NA sink estimate, thus suggesting some convergence with the modeling approaches.
Published: 2012
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20. The terrestrial biosphere as a net source of greenhouse gases to the atmosphere

Author: Marielle Saunois, Philippe Bousquet, Pierre Friedlingstein, Guangsheng Chen, Kevin R. Gurney, Anna M. Michalak, Chaoqun Lu, Shufen Pan, Stephen Sitch, Hanqin Tian, Deborah N. Huntzinger, Jia Yang, Christopher R. Schwalm, Philippe Ciais, Benjamin Poulter, Ronald G. Prinn, Lori Bruhwiler, Edward J. Dlugokencky, Steven C. Wofsy, Eri Saikawa, Bowen Zhang, Jerry M. Melillo, Josep G. Canadell, Massachusetts Institute of Technology. Center for Global Change Science, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Prinn, Ronald G, Auburn University (AU), Iowa State University (ISU), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-ATC (ICOS-ATC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Carnegie Observatories, Carnegie Institution for Science [Washington], Commonwealth Scientific and Industrial Research Organisation [Canberra] (CSIRO), Emory University [Atlanta, GA], Northern Arizona University [Flagstaff], Arizona State University [Tempe] (ASU), University of Exeter, Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), NOAA Earth System Research Laboratory (ESRL), National Oceanic and Atmospheric Administration (NOAA), Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC, College of Engineering, Mathematics and Physical Sciences [Exeter] (EMPS), Woods Hole Oceanographic Institution (WHOI), Montana State University (MSU), Massachusetts Institute of Technology (MIT), Harvard University [Cambridge], Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Carnegie Institution for Science, and Harvard University
Subjects: Greenhouse Effect, Asia, 010504 meteorology & atmospheric sciences, Atmospheric carbon cycle, Nitrous Oxide, Climate change, Carbon dioxide equivalent, 010501 environmental sciences, Atmospheric sciences, 7. Clean energy, 01 natural sciences, Global Warming, Methane, chemistry.chemical_compound, Greenhouse gas removal, Human Activities, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Ecosystem, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Multidisciplinary, Ecology, Atmosphere, Atmospheric methane, Agriculture, Nitrous oxide, 15. Life on land, Carbon Dioxide, chemistry, 13. Climate action, Greenhouse gas, Environmental science
Abstract: The terrestrial biosphere can release or absorb the greenhouse gases, carbon dioxide (CO[subscript 2]), methane (CH[subscript 4]) and nitrous oxide (N[subscript 2]O), and therefore has an important role in regulating atmospheric composition and climate. Anthropogenic activities such as land-use change, agriculture and waste management have altered terrestrial biogenic greenhouse gas fluxes, and the resulting increases in methane and nitrous oxide emissions in particular can contribute to climate change. The terrestrial biogenic fluxes of individual greenhouse gases have been studied extensively,but the net biogenic greenhouse gas balance resulting from anthropogenic activities and its effect on the climate system remains uncertain. Here we use bottom-up (inventory, statistical extrapolation of local flux measurements, and process-based modelling) and top-down (atmospheric inversions) approaches to quantify the global net biogenic greenhouse gas balance between 1981 and 2010 resulting from anthropogenic activities and its effect on the climate system. We find that the cumulative warming capacity of concurrent biogenic methane and nitrous oxide emissions is a factor of about two larger than the cooling effect resulting from the global land carbon dioxide uptake from 2001 to 2010. This results in a net positive cumulative impact of the three greenhouse gases on the planetary energy budget, with a best estimate (in petagrams of CO[subscript 2] equivalent per year) of 3.9 ± 3.8 (top down) and 5.4 ± 4.8 (bottom up) based on the GWP100 metric (global warming potential on a 100-year time horizon). Our findings suggest that a reduction in agricultural methane and nitrous oxide emissions, particularly in Southern Asia, may help mitigate climate change., United States. National Aeronautics and Space Administration (NASA Grant NNX08AL73G), United States. National Aeronautics and Space Administration (NASA Grant NNX14AO73G), United States. National Aeronautics and Space Administration (NASA Grant NNX10AU06G), United States. National Aeronautics and Space Administration (NASA Grant NNX11AD47G), United States. National Aeronautics and Space Administration (NASA Grant NNG04GM39C), National Science Foundation (U.S.) (NSF grant AGS 1243232), National Science Foundation (U.S.) (Grant AGS-1243220), National Science Foundation (U.S.) (NSF grant CNH1210360), United States. National Oceanic and Atmospheric Administration (NOAA Climate Program Office award NA13OAR4310059), Australian Climate Change Science Programme, National Science Foundation (U.S.) (NSF CAREER (AGS-0846358)), United States. National Aeronautics and Space Administration (NASA Upper Atmosphere Research Program AGAGE, grant NNX11AF17G)
Published: 2015
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21. Global land carbon sink response to temperature and precipitation varies with ENSO phase

Author: Weile Wang, Yaxing Wei, Deborah N. Huntzinger, Daniel M. Ricciuto, Xiaoying Shi, Anna M. Michalak, Chaoqun Lu, Atul K. Jain, Robert B. Cook, Christopher R. Schwalm, Yuanyuan Fang, Joshua B. Fisher, Daniel J. Hayes, Benjamin Poulter, Jia Yang, Bo Tao, Hanqin Tian, Joseph A. Berry, Nicholas C. Parazoo, Huimin Lei, Shushi Peng, Jiafu Mao, Shilong Piao, Akihiko Ito, Philippe Ciais, Maoyi Huang, Department of Chemistry [University of Houston], University of Houston, Carnegie Observatories, Carnegie Institution for Science [Washington], Northern Arizona University [Flagstaff], Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-ATC (ICOS-ATC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Sino-French Institute for Earth System Science, College of Urban and Environmental Sciences, Peking University [Beijing], Montana State University (MSU), University of Oxford [Oxford], Cyprus Oceanography Center, University of Cyprus (UCY), National Institute for Environmental Studies (NIES), Department of Atmospheric Sciences [Urbana], University of Illinois at Urbana-Champaign [Urbana], University of Illinois System-University of Illinois System, Auburn University (AU), Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC, California Institute of Technology (CALTECH), Environmental Sciences Division [Oak Ridge], UT-Battelle, LLC-UT-Battelle, LLC, Shandong Agricultural University (SDAU), Carnegie Institution for Science, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), University of Oxford, and University of Cyprus [Nicosia] (UCY)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 0106 biological sciences, 010504 meteorology & atmospheric sciences, Renewable Energy, Sustainability and the Environment, Public Health, Environmental and Occupational Health, Climate change, Carbon sink, chemistry.chemical_element, Carbon sequestration, Atmospheric sciences, 010603 evolutionary biology, 01 natural sciences, Carbon cycle, El Niño Southern Oscillation, chemistry, 13. Climate action, Climatology, Phase (matter), Environmental science, Precipitation, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Carbon, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, General Environmental Science
Abstract: International audience
Published: 2017
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22. Carbon cycle uncertainty in the Alaskan Arctic

Author: M. A. Arain, A. K. Sahoo, Philippe Ciais, Enrico Tomelleri, Walter C. Oechel, Daniel J. Hayes, Chris Huntingford, Deborah N. Huntzinger, David Price, Mark R. Lomas, Ning Zeng, Kevin Schaefer, Ian Baker, Carl C. Davidson, Atul K. Jain, R. Wania, Hans Verbeeck, Joe R. Melton, Hanqin Tian, Peter Levy, Benjamin Poulter, Bassil El-Masri, Charles D. Koven, Michael Dietze, Joshua B. Fisher, Anders Ahlström, Nicolas Viovy, Charles E. Miller, Jing M. Chen, Munish Sikka, Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), San Diego State University (SDSU), Northern Arizona University [Flagstaff], Canadian Centre for Climate Modelling and Analysis (CCCma), Environment and Climate Change Canada, Lawrence Berkeley National Laboratory [Berkeley] (LBNL), Lund University [Lund], McMaster University [Hamilton, Ontario], Colorado State University [Fort Collins] (CSU), Department of Geography and Planning [University of Toronto], University of Toronto, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), ICOS-ATC (ICOS-ATC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), University of Illinois at Urbana-Champaign [Urbana], University of Illinois System, Boston University [Boston] (BU), Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC, Centre for Ecology and Hydrology [Wallingford] (CEH), Natural Environment Research Council (NERC), Centre for Ecology and Hydrology (CEH), University of Sheffield [Sheffield], Montana State University (MSU), Natural Resources Canada (NRCan), Princeton University, National Snow and Ice Data Center (NSIDC), University of Colorado [Boulder], Auburn University (AU), Max Planck Institute for Biogeochemistry (MPI-BGC), Max-Planck-Gesellschaft, Universiteit Gent = Ghent University (UGENT), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), Institut des Sciences de l'Evolution de Montpellier (UMR ISEM), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Institut de recherche pour le développement [IRD] : UR226-Centre National de la Recherche Scientifique (CNRS), Department of Atmospheric and Oceanic Science [College Park] (AOSC), University of Maryland [College Park], University of Maryland System-University of Maryland System, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Universiteit Gent = Ghent University [Belgium] (UGENT), École pratique des hautes études (EPHE), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Montpellier (UM)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre National de la Recherche Scientifique (CNRS)-Institut de recherche pour le développement [IRD] : UR226
Subjects: 010504 meteorology & atmospheric sciences, WETLAND EXTENT, lcsh:Life, chemistry.chemical_element, Climate change, Atmospheric sciences, 01 natural sciences, GLOBAL VEGETATION MODEL, Atmospheric Sciences, ATMOSPHERIC INVERSIONS, Carbon cycle, 03 medical and health sciences, Meteorology and Climatology, lcsh:QH540-549.5, METHANE EMISSIONS, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, TERRESTRIAL BIOSPHERE, Ecology, Evolution, Behavior and Systematics, Earth-Surface Processes, 030304 developmental biology, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 0303 health sciences, CLIMATE-CHANGE, lcsh:QE1-996.5, Primary production, Carbon sink, Soil carbon, 15. Life on land, PERMAFROST CARBON, lcsh:Geology, lcsh:QH501-531, TUNDRA ECOSYSTEMS, Arctic, chemistry, COMPARISON PROJECT WETCHIMP, 13. Climate action, Earth and Environmental Sciences, Climatology, Earth Sciences, Environmental science, lcsh:Ecology, Hydrology, PRESENT STATE, Ecosystem respiration, Carbon
Abstract: Climate change is leading to a disproportionately large warming in the high northern latitudes, but the magnitude and sign of the future carbon balance of the Arctic are highly uncertain. Using 40 terrestrial biosphere models for the Alaskan Arctic from four recent model intercomparison projects – NACP (North American Carbon Program) site and regional syntheses, TRENDY (Trends in net land atmosphere carbon exchanges), and WETCHIMP (Wetland and Wetland CH4 Inter-comparison of Models Project) – we provide a baseline of terrestrial carbon cycle uncertainty, defined as the multi-model standard deviation (σ) for each quantity that follows. Mean annual absolute uncertainty was largest for soil carbon (14.0 ± 9.2 kg C m−2), then gross primary production (GPP) (0.22 ± 0.50 kg C m−2 yr−1), ecosystem respiration (Re) (0.23 ± 0.38 kg C m−2 yr−1), net primary production (NPP) (0.14 ± 0.33 kg C m−2 yr−1), autotrophic respiration (Ra) (0.09 ± 0.20 kg C m−2 yr−1), heterotrophic respiration (Rh) (0.14 ± 0.20 kg C m−2 yr−1), net ecosystem exchange (NEE) (−0.01 ± 0.19 kg C m−2 yr−1), and CH4 flux (2.52 ± 4.02 g CH4 m−2 yr−1). There were no consistent spatial patterns in the larger Alaskan Arctic and boreal regional carbon stocks and fluxes, with some models showing NEE for Alaska as a strong carbon sink, others as a strong carbon source, while still others as carbon neutral. Finally, AmeriFlux data are used at two sites in the Alaskan Arctic to evaluate the regional patterns; observed seasonal NEE was captured within multi-model uncertainty. This assessment of carbon cycle uncertainties may be used as a baseline for the improvement of experimental and modeling activities, as well as a reference for future trajectories in carbon cycling with climate change in the Alaskan Arctic and larger boreal region.
Published: 2014
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23. North American Carbon Program (NACP) regional interim synthesis: Terrestrial biospheric model intercomparison

Author: Wenping Yuan, Atul K. Jain, Robert B. Cook, Peter E. Thornton, Shuguang Liu, Enrico Tomelleri, Nicolas Viovy, Tristram O. West, Kenneth J. Davis, A. D. McGuire, Deborah N. Huntzinger, Ronald P. Neilson, Jingfeng Xiao, Ning Zeng, Anna M. Michalak, Daniel J. Hayes, Maosheng Zhao, Benjamin Poulter, Andrew R. Jacobson, Hanqin Tian, Jing M. Chen, Yaxing Wei, Wilfred M. Post, Christopher Potter, David Price, Brett Raczka, Ian Baker, Forrest M. Hoffman, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation INVerse pour les mesures atmosphériques et SATellitaires (SATINV), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Modélisation des Surfaces et Interfaces Continentales (MOSAIC), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010504 meteorology & atmospheric sciences, Ecology, Ecological Modeling, Biosphere, 04 agricultural and veterinary sciences, Soil carbon, 15. Life on land, Atmospheric sciences, 01 natural sciences, Carbon cycle, 13. Climate action, Carbon source, Soil water, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental science, Ecosystem, Terrestrial ecosystem, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Carbon flux
Abstract: Understanding of carbon exchange between terrestrial ecosystems and the atmosphere can be improved through direct observations and experiments, as well as through modeling activities. Terrestrial biosphere models (TBMs) have become an integral tool for extrapolating local observations and understanding to much larger terrestrial regions. Although models vary in their specific goals and approaches, their central role within carbon cycle science is to provide a better understanding of the mechanisms currently controlling carbon exchange. Recently, the North American Carbon Program (NACP) organized several interim-synthesis activities to evaluate and inter-compare models and observations at local to continental scales for the years 2000-2005. Here, we compare the results from the TBMs collected as part of the regional and continental interim-synthesis (RCIS) activities. The primary objective of this work is to synthesize and compare the 19 participating TBMs to assess current understanding of the terrestrial carbon cycle in North America. Thus, the RCIS focuses on model simulations available from analyses that have been completed by ongoing NACP projects and other recently published studies. The TBM flux estimates are compared and evaluated over different spatial (1{sup o} x 1{sup o} and spatially aggregated to different regions) and temporal (monthly and annually) scales. The range inmore » model estimates of net ecosystem productivity (NEP) for North America is much narrower than estimates of productivity or respiration, with estimates of NEP varying between -0.7 and 2.2 PgC yr{sup -1}, while gross primary productivity and heterotrophic respiration vary between 12.2 and 32.9 PgC yr{sup -1} and 5.6 and 13.2 PgC yr{sup -1}, respectively. The range in estimates from the models appears to be driven by a combination of factors, including the representation of photosynthesis, the source and of environmental driver data and the temporal variability of those data, as well as whether nutrient limitation is considered in soil carbon decomposition. The disagreement in current estimates of carbon flux across North America, including whether North America is a net biospheric carbon source or sink, highlights the need for further analysis through the use of model runs following a common simulation protocol, in order to isolate the influences of model formulation, structure, and assumptions on flux estimates.« less
Published: 2012
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24. Global patterns and controls of soil organic carbon dynamics as simulated by multiple terrestrial biosphere models: Current status and future directions

Author: Benjamin Poulter, Huimin Lei, Anna M. Michalak, Chaoqun Lu, Kamaljit Banger, Hanqin Tian, Wei Ren, Daniel J. Hayes, Bowen Zhang, Akihiko Ito, Philippe Ciais, Shushi Peng, Jia Yang, Yaxing Wei, Shufen Pan, Jiafu Mao, Weile Wang, Deborah N. Huntzinger, Bo Tao, Christopher R. Schwalm, Kevin Schaefer, Ning Zeng, Daniel M. Ricciuto, Xiaoying Shi, Qichun Yang, Wilfred M. Post, Atul K. Jain, Robert B. Cook, Maoyi Huang, Auburn University (AU), Northern Arizona University [Flagstaff], Carnegie Institution for Science [Washington], Oak Ridge National Laboratory [Oak Ridge] (ORNL), UT-Battelle, LLC, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), ICOS-ATC (ICOS-ATC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), National Institute for Environmental Studies (NIES), University of Illinois at Urbana-Champaign [Urbana], University of Illinois System, Tsinghua University [Beijing] (THU), Montana State University (MSU), State Key Lab of Advanced Optical Communication Systems and Networks (Shanghai Jiao Tong University), Environmental Sciences Division [Oak Ridge], UT-Battelle, LLC-UT-Battelle, LLC, Carnegie Institution for Science, Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), and Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atmospheric Science, 010504 meteorology & atmospheric sciences, Climate change, Soil science, Biogeosciences, Atmospheric sciences, 01 natural sciences, Soils/Pedology, Carbon cycle, Biogeochemical Kinetics and Reaction Modeling, Global Change from Geodesy, Oceanography: Biological and Chemical, heterotrophic respiration (Rh), Paleoceanography, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Environmental Chemistry, Geodesy and Gravity, Global Change, soil carbon dynamics model, uncertainty, Research Articles, 0105 earth and related environmental sciences, General Environmental Science, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Global and Planetary Change, Carbon dioxide in Earth's atmosphere, Soil organic matter, Biosphere, 04 agricultural and veterinary sciences, Soil carbon, Biogeochemistry, 15. Life on land, Climate Impact, soil organic carbon (SOC), 13. Climate action, 040103 agronomy & agriculture, Soils, 0401 agriculture, forestry, and fisheries, Soil horizon, Environmental science, Terrestrial ecosystem, Hydrology, mean residence time (MRT), Cryosphere, belowground processes, Biogeochemical Cycles, Processes, and Modeling, Impacts of Global Change, Natural Hazards, Research Article
Abstract: Soil is the largest organic carbon (C) pool of terrestrial ecosystems, and C loss from soil accounts for a large proportion of land‐atmosphere C exchange. Therefore, a small change in soil organic C (SOC) can affect atmospheric carbon dioxide (CO2) concentration and climate change. In the past decades, a wide variety of studies have been conducted to quantify global SOC stocks and soil C exchange with the atmosphere through site measurements, inventories, and empirical/process‐based modeling. However, these estimates are highly uncertain, and identifying major driving forces controlling soil C dynamics remains a key research challenge. This study has compiled century‐long (1901–2010) estimates of SOC storage and heterotrophic respiration (Rh) from 10 terrestrial biosphere models (TBMs) in the Multi‐scale Synthesis and Terrestrial Model Intercomparison Project and two observation‐based data sets. The 10 TBM ensemble shows that global SOC estimate ranges from 425 to 2111 Pg C (1 Pg = 1015 g) with a median value of 1158 Pg C in 2010. The models estimate a broad range of Rh from 35 to 69 Pg C yr−1 with a median value of 51 Pg C yr−1 during 2001–2010. The largest uncertainty in SOC stocks exists in the 40–65°N latitude whereas the largest cross‐model divergence in Rh are in the tropics. The modeled SOC change during 1901–2010 ranges from −70 Pg C to 86 Pg C, but in some models the SOC change has a different sign from the change of total C stock, implying very different contribution of vegetation and soil pools in determining the terrestrial C budget among models. The model ensemble‐estimated mean residence time of SOC shows a reduction of 3.4 years over the past century, which accelerate C cycling through the land biosphere. All the models agreed that climate and land use changes decreased SOC stocks, while elevated atmospheric CO2 and nitrogen deposition over intact ecosystems increased SOC stocks—even though the responses varied significantly among models. Model representations of temperature and moisture sensitivity, nutrient limitation, and land use partially explain the divergent estimates of global SOC stocks and soil C fluxes in this study. In addition, a major source of systematic error in model estimations relates to nonmodeled SOC storage in wetlands and peatlands, as well as to old C storage in deep soil layers., Key Points Simulated historical (1901–2010) SOC dynamics vary largely among modelsTen TBMs agree that climate and land use change have reduced SOC stocksRising CO2 and N deposition are prone to increase SOC with varying magnitudes
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24 results on '"Deborah N. Huntzinger"'

1. Linking global terrestrial CO2 fluxes and environmental drivers: inferences from the Orbiting Carbon Observatory 2 satellite and terrestrial biospheric models

2. Impacts of land use change and elevated CO2 on the interannual variations and seasonal cycles of gross primary productivity in China

3. The Terrestrial Biosphere Model Farm

4. Five years of variability in the global carbon cycle: comparing an estimate from the Orbiting Carbon Observatory-2 and process-based models

5. Large‐Scale Reductions in Terrestrial Carbon Uptake Following Central Pacific El Niño

6. Linking global terrestrial CO2 fluxes and environmental drivers using OCO-2 and a geostatistical inverse model

7. Enhanced peak growth of global vegetation and its key mechanisms

8. Exploring the environmental drivers of global terrestrial CO2 fluxes inferred from OCO-2 and a geostatistical inverse model

9. Field-experiment constraints on the enhancement of the terrestrial carbon sink by CO2 fertilization

10. Global vegetation biomass production efficiency constrained by models and observations

11. Land carbon models underestimate the severity and duration of drought’s impact on plant productivity

12. Accelerating rates of Arctic carbon cycling revealed by long-term atmospheric CO 2 measurements

13. How well do terrestrial biosphere models simulate coarse-scale runoff in the contiguous United States?

14. Response of Water Use Efficiency to Global Environmental Change Based on Output From Terrestrial Biosphere Models

15. Impact of large-scale climate extremes on biospheric carbon fluxes: An intercomparison based on MsTMIP data

16. The North American Carbon Program Multi-Scale Synthesis and Terrestrial Model Intercomparison Project – Part 1: Overview and experimental design

17. Uncertainty in the response of terrestrial carbon sink to environmental drivers undermines carbon-climate feedback predictions

18. North American carbon dioxide sources and sinks: magnitude, attribution, and uncertainty

19. Reconciling estimates of the contemporary North American carbon balance among terrestrial biosphere models, atmospheric inversions, and a new approach for estimating net ecosystem exchange from inventory-based data

20. The terrestrial biosphere as a net source of greenhouse gases to the atmosphere

21. Global land carbon sink response to temperature and precipitation varies with ENSO phase

22. Carbon cycle uncertainty in the Alaskan Arctic

23. North American Carbon Program (NACP) regional interim synthesis: Terrestrial biospheric model intercomparison

24. Global patterns and controls of soil organic carbon dynamics as simulated by multiple terrestrial biosphere models: Current status and future directions

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