Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO2

Anthony P. Walker; Martin G. De Kauwe; Ana Bastos; Soumaya Belmecheri; Katerina Georgiou; Ralph F. Keeling; Sean M. McMahon; Belinda E. Medlyn; David J.P. Moore; Richard J. Norby; Sönke Zaehle; Kristina J. Anderson-Teixeira; Giovanna Battipaglia; Roel J.W. Brienen; Kristine G. Cabugao; Maxime Cailleret; Elliott Campbell; Josep G. Canadell; Philippe Ciais; Matthew E. Craig; David S. Ellsworth; Graham D. Farquhar; Simone Fatichi; Joshua B. Fisher; David C. Frank; Heather Graven; Lianhong Gu; Vanessa Haverd; Kelly Heilman; Martin Heimann; Bruce A. Hungate; Colleen M. Iversen; Fortunat Joos; Mingkai Jiang; Trevor F. Keenan; Jürgen Knauer; Christian Körner; Victor O. Leshyk; Sebastian Leuzinger; Yao Liu; Natasha MacBean; Yadvinder Malhi; Tim R. McVicar; Josep Penuelas; Julia Pongratz; A. Shafer Powell; Terhi Riutta; Manon E.B. Sabot; Juergen Schleucher; Stephen Sitch; William K. Smith; Benjamin Sulman; Benton Taylor; César Terrer; Margaret S. Torn; Kathleen K. Treseder; Anna T. Trugman; Susan E. Trumbore; Phillip J. van Mantgem; Steve L. Voelker; Mary E. Whelan; Pieter A. Zuidema

doi:10.1111/nph.16866

Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO₂

Anthony P. Walker, Martin G. De Kauwe, Ana Bastos, Soumaya Belmecheri, Katerina Georgiou, Ralph F. Keeling, Sean M. McMahon, Belinda E. Medlyn, David J.P. Moore, Richard J. Norby, Sönke Zaehle, Kristina J. Anderson-Teixeira, Giovanna Battipaglia, Roel J.W. Brienen, Kristine G. Cabugao, Maxime Cailleret, Elliott Campbell, Josep G. Canadell, Philippe Ciais, Matthew E. CraigDavid S. Ellsworth, Graham D. Farquhar, Simone Fatichi, Joshua B. Fisher, David C. Frank, Heather Graven, Lianhong Gu, Vanessa Haverd, Kelly Heilman, Martin Heimann, Bruce A. Hungate, Colleen M. Iversen, Fortunat Joos, Mingkai Jiang, Trevor F. Keenan, Jürgen Knauer, Christian Körner, Victor O. Leshyk, Sebastian Leuzinger, Yao Liu, Natasha MacBean, Yadvinder Malhi, Tim R. McVicar, Josep Penuelas, Julia Pongratz, A. Shafer Powell, Terhi Riutta, Manon E.B. Sabot, Juergen Schleucher, Stephen Sitch, William K. Smith, Benjamin Sulman, Benton Taylor, César Terrer, Margaret S. Torn, Kathleen K. Treseder, Anna T. Trugman, Susan E. Trumbore, Phillip J. van Mantgem, Steve L. Voelker, Mary E. Whelan, Pieter A. Zuidema

Research output: Contribution to journal › Review article › peer-review

99 Scopus citations

Abstract

Atmospheric carbon dioxide concentration ([CO₂]) is increasing, which increases leaf-scale photosynthesis and intrinsic water-use efficiency. These direct responses have the potential to increase plant growth, vegetation biomass, and soil organic matter; transferring carbon from the atmosphere into terrestrial ecosystems (a carbon sink). A substantial global terrestrial carbon sink would slow the rate of [CO₂] increase and thus climate change. However, ecosystem CO₂ responses are complex or confounded by concurrent changes in multiple agents of global change and evidence for a [CO₂]-driven terrestrial carbon sink can appear contradictory. Here we synthesize theory and broad, multidisciplinary evidence for the effects of increasing [CO₂] (iCO₂) on the global terrestrial carbon sink. Evidence suggests a substantial increase in global photosynthesis since pre-industrial times. Established theory, supported by experiments, indicates that iCO₂ is likely responsible for about half of the increase. Global carbon budgeting, atmospheric data, and forest inventories indicate a historical carbon sink, and these apparent iCO₂ responses are high in comparison to experiments and predictions from theory. Plant mortality and soil carbon iCO₂ responses are highly uncertain. In conclusion, a range of evidence supports a positive terrestrial carbon sink in response to iCO₂, albeit with uncertain magnitude and strong suggestion of a role for additional agents of global change.

Original language	English (US)
Pages (from-to)	2413-2445
Number of pages	33
Journal	New Phytologist
Volume	229
Issue number	5
DOIs	https://doi.org/10.1111/nph.16866
State	Published - Mar 2021

Keywords

CO fertilization
CO-fertilization hypothesis
beta factor
carbon dioxide
free-air CO enrichment (FACE)
global carbon cycle
land–atmosphere feedback
terrestrial ecosystems

ASJC Scopus subject areas

Physiology
Plant Science

Access to Document

10.1111/nph.16866

Cite this

Walker, A. P., De Kauwe, M. G., Bastos, A., Belmecheri, S., Georgiou, K., Keeling, R. F., McMahon, S. M., Medlyn, B. E., Moore, D. J. P., Norby, R. J., Zaehle, S., Anderson-Teixeira, K. J., Battipaglia, G., Brienen, R. J. W., Cabugao, K. G., Cailleret, M., Campbell, E., Canadell, J. G., Ciais, P., ... Zuidema, P. A. (2021). Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO₂. New Phytologist, 229(5), 2413-2445. https://doi.org/10.1111/nph.16866

Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO₂. / Walker, Anthony P.; De Kauwe, Martin G.; Bastos, Ana; Belmecheri, Soumaya; Georgiou, Katerina; Keeling, Ralph F.; McMahon, Sean M.; Medlyn, Belinda E.; Moore, David J.P.; Norby, Richard J.; Zaehle, Sönke; Anderson-Teixeira, Kristina J.; Battipaglia, Giovanna; Brienen, Roel J.W.; Cabugao, Kristine G.; Cailleret, Maxime; Campbell, Elliott; Canadell, Josep G.; Ciais, Philippe; Craig, Matthew E.; Ellsworth, David S.; Farquhar, Graham D.; Fatichi, Simone; Fisher, Joshua B.; Frank, David C.; Graven, Heather; Gu, Lianhong; Haverd, Vanessa; Heilman, Kelly; Heimann, Martin; Hungate, Bruce A.; Iversen, Colleen M.; Joos, Fortunat; Jiang, Mingkai; Keenan, Trevor F.; Knauer, Jürgen; Körner, Christian; Leshyk, Victor O.; Leuzinger, Sebastian; Liu, Yao; MacBean, Natasha; Malhi, Yadvinder; McVicar, Tim R.; Penuelas, Josep; Pongratz, Julia; Powell, A. Shafer; Riutta, Terhi; Sabot, Manon E.B.; Schleucher, Juergen; Sitch, Stephen; Smith, William K.; Sulman, Benjamin; Taylor, Benton; Terrer, César; Torn, Margaret S.; Treseder, Kathleen K.; Trugman, Anna T.; Trumbore, Susan E.; van Mantgem, Phillip J.; Voelker, Steve L.; Whelan, Mary E.; Zuidema, Pieter A.

In: New Phytologist, Vol. 229, No. 5, 03.2021, p. 2413-2445.

Research output: Contribution to journal › Review article › peer-review

Walker, AP, De Kauwe, MG, Bastos, A, Belmecheri, S, Georgiou, K, Keeling, RF, McMahon, SM, Medlyn, BE, Moore, DJP, Norby, RJ, Zaehle, S, Anderson-Teixeira, KJ, Battipaglia, G, Brienen, RJW, Cabugao, KG, Cailleret, M, Campbell, E, Canadell, JG, Ciais, P, Craig, ME, Ellsworth, DS, Farquhar, GD, Fatichi, S, Fisher, JB, Frank, DC, Graven, H, Gu, L, Haverd, V, Heilman, K, Heimann, M, Hungate, BA, Iversen, CM, Joos, F, Jiang, M, Keenan, TF, Knauer, J, Körner, C, Leshyk, VO, Leuzinger, S, Liu, Y, MacBean, N, Malhi, Y, McVicar, TR, Penuelas, J, Pongratz, J, Powell, AS, Riutta, T, Sabot, MEB, Schleucher, J, Sitch, S, Smith, WK, Sulman, B, Taylor, B, Terrer, C, Torn, MS, Treseder, KK, Trugman, AT, Trumbore, SE, van Mantgem, PJ, Voelker, SL, Whelan, ME & Zuidema, PA 2021, 'Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO₂', New Phytologist, vol. 229, no. 5, pp. 2413-2445. https://doi.org/10.1111/nph.16866

Walker, Anthony P. ; De Kauwe, Martin G. ; Bastos, Ana ; Belmecheri, Soumaya ; Georgiou, Katerina ; Keeling, Ralph F. ; McMahon, Sean M. ; Medlyn, Belinda E. ; Moore, David J.P. ; Norby, Richard J. ; Zaehle, Sönke ; Anderson-Teixeira, Kristina J. ; Battipaglia, Giovanna ; Brienen, Roel J.W. ; Cabugao, Kristine G. ; Cailleret, Maxime ; Campbell, Elliott ; Canadell, Josep G. ; Ciais, Philippe ; Craig, Matthew E. ; Ellsworth, David S. ; Farquhar, Graham D. ; Fatichi, Simone ; Fisher, Joshua B. ; Frank, David C. ; Graven, Heather ; Gu, Lianhong ; Haverd, Vanessa ; Heilman, Kelly ; Heimann, Martin ; Hungate, Bruce A. ; Iversen, Colleen M. ; Joos, Fortunat ; Jiang, Mingkai ; Keenan, Trevor F. ; Knauer, Jürgen ; Körner, Christian ; Leshyk, Victor O. ; Leuzinger, Sebastian ; Liu, Yao ; MacBean, Natasha ; Malhi, Yadvinder ; McVicar, Tim R. ; Penuelas, Josep ; Pongratz, Julia ; Powell, A. Shafer ; Riutta, Terhi ; Sabot, Manon E.B. ; Schleucher, Juergen ; Sitch, Stephen ; Smith, William K. ; Sulman, Benjamin ; Taylor, Benton ; Terrer, César ; Torn, Margaret S. ; Treseder, Kathleen K. ; Trugman, Anna T. ; Trumbore, Susan E. ; van Mantgem, Phillip J. ; Voelker, Steve L. ; Whelan, Mary E. ; Zuidema, Pieter A. / Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO₂. In: New Phytologist. 2021 ; Vol. 229, No. 5. pp. 2413-2445.

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title = "Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO2",

abstract = "Atmospheric carbon dioxide concentration ([CO2]) is increasing, which increases leaf-scale photosynthesis and intrinsic water-use efficiency. These direct responses have the potential to increase plant growth, vegetation biomass, and soil organic matter; transferring carbon from the atmosphere into terrestrial ecosystems (a carbon sink). A substantial global terrestrial carbon sink would slow the rate of [CO2] increase and thus climate change. However, ecosystem CO2 responses are complex or confounded by concurrent changes in multiple agents of global change and evidence for a [CO2]-driven terrestrial carbon sink can appear contradictory. Here we synthesize theory and broad, multidisciplinary evidence for the effects of increasing [CO2] (iCO2) on the global terrestrial carbon sink. Evidence suggests a substantial increase in global photosynthesis since pre-industrial times. Established theory, supported by experiments, indicates that iCO2 is likely responsible for about half of the increase. Global carbon budgeting, atmospheric data, and forest inventories indicate a historical carbon sink, and these apparent iCO2 responses are high in comparison to experiments and predictions from theory. Plant mortality and soil carbon iCO2 responses are highly uncertain. In conclusion, a range of evidence supports a positive terrestrial carbon sink in response to iCO2, albeit with uncertain magnitude and strong suggestion of a role for additional agents of global change.",

keywords = "CO fertilization, CO-fertilization hypothesis, beta factor, carbon dioxide, free-air CO enrichment (FACE), global carbon cycle, land–atmosphere feedback, terrestrial ecosystems",

author = "Walker, {Anthony P.} and {De Kauwe}, {Martin G.} and Ana Bastos and Soumaya Belmecheri and Katerina Georgiou and Keeling, {Ralph F.} and McMahon, {Sean M.} and Medlyn, {Belinda E.} and Moore, {David J.P.} and Norby, {Richard J.} and S{\"o}nke Zaehle and Anderson-Teixeira, {Kristina J.} and Giovanna Battipaglia and Brienen, {Roel J.W.} and Cabugao, {Kristine G.} and Maxime Cailleret and Elliott Campbell and Canadell, {Josep G.} and Philippe Ciais and Craig, {Matthew E.} and Ellsworth, {David S.} and Farquhar, {Graham D.} and Simone Fatichi and Fisher, {Joshua B.} and Frank, {David C.} and Heather Graven and Lianhong Gu and Vanessa Haverd and Kelly Heilman and Martin Heimann and Hungate, {Bruce A.} and Iversen, {Colleen M.} and Fortunat Joos and Mingkai Jiang and Keenan, {Trevor F.} and J{\"u}rgen Knauer and Christian K{\"o}rner and Leshyk, {Victor O.} and Sebastian Leuzinger and Yao Liu and Natasha MacBean and Yadvinder Malhi and McVicar, {Tim R.} and Josep Penuelas and Julia Pongratz and Powell, {A. Shafer} and Terhi Riutta and Sabot, {Manon E.B.} and Juergen Schleucher and Stephen Sitch and Smith, {William K.} and Benjamin Sulman and Benton Taylor and C{\'e}sar Terrer and Torn, {Margaret S.} and Treseder, {Kathleen K.} and Trugman, {Anna T.} and Trumbore, {Susan E.} and {van Mantgem}, {Phillip J.} and Voelker, {Steve L.} and Whelan, {Mary E.} and Zuidema, {Pieter A.}",

note = "Funding Information: This paper was outlined and informed by the {\textquoteleft}Integrating CO‐fertilization evidence streams and theory (ICOFEST){\textquoteright} meeting held at Biosphere II in September 2018. The meeting was supported by the US Department of Energy Office of Science, Biological and Environmental Research through the Free Air CO Enrichment Model Data Synthesis (FACE‐MDS) project. ORNL is managed by UT‐Battelle, LLC, for the DOE under contract DE‐AC05‐00OR22725. MGDK acknowledges support from Australian Research Council (ARC) Discovery Grant (DP190101823). DJPM and WKS acknowledge support from NASA Terrestrial Ecosystems Grant 80NSSC19M0103. SZ received funding from the European Research Council (ERC) under the European Union{\textquoteright}s Horizon 2020 research and innovation programme (grant agreement no. 647204). KJAT acknowledges support from the Smithsonian's Forest Global Earth Observatory (ForestGEO). JBF contributed to this research at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration with support from the NASA IDS program. VH acknowledges support from the Earth Systems and Climate Change Hub, funded by the Australian Research Council. FJ acknowledges support by the Swiss NSF (no. 200020_172476). TFK was supported by the NASA Terrestrial Ecology Program IDS Award NNH17AE86I. PC and JP were supported by the European Research Council Synergy grant ERC‐2013‐SyG‐2013‐610028 IMBALANCE‐P. J. Pongratz was supported by the German Research Foundation{\textquoteright}s Emmy Noether Program. MEBS acknowledges support from the Australian Research Council Centre of Excellence for Climate Extremes (CE170100023). JS acknowledges support from VR, KAW and Kempe foundations. CT was supported by a Lawrence Fellow award through Lawrence Livermore National Laboratory (LLNL) under contract DE‐AC52‐07NA27344 with the US Department of Energy and the LLNL‐LDRD Program under Project No. 20‐ERD‐055. MST was supported by the US Department of Energy, Office of Science under contract number DE‐AC02‐05CH11231. ATT acknowledges funding from the USDA National Institute of Food and Agriculture, Agricultural and Food Research Initiative Competitive Programme grant no. 2018‐67012‐31496 and the University of California Laboratory Fees Research Program Award No. LFR‐20‐652467. SLV was supported by the US National Science Foundation Paleo Perspectives on Climate Change Program. PvM was supported by the US Geological Survey Ecosystems Mission Area. Government sponsorship is acknowledged. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US Government. 2 2 Funding Information: This paper was outlined and informed by the ?Integrating CO2-fertilization evidence streams and theory (ICOFEST)? meeting held at Biosphere II in September 2018. The meeting was supported by the US Department of Energy Office of Science, Biological and Environmental Research through the Free Air CO2 Enrichment Model Data Synthesis (FACE-MDS) project. ORNL is managed by UT-Battelle, LLC, for the DOE under contract DE-AC05-00OR22725. MGDK acknowledges support from Australian Research Council (ARC) Discovery Grant (DP190101823). DJPM and WKS acknowledge support from NASA Terrestrial Ecosystems Grant 80NSSC19M0103. SZ received funding from the European Research Council (ERC) under the European Union?s Horizon 2020 research and innovation programme (grant agreement no. 647204). KJAT acknowledges support from the Smithsonian's Forest Global Earth Observatory (ForestGEO). JBF contributed to this research at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration with support from the NASA IDS program. VH acknowledges support from the Earth Systems and Climate Change Hub, funded by the Australian Research Council. FJ acknowledges support by the Swiss NSF (no. 200020_172476). TFK was supported by the NASA Terrestrial Ecology Program IDS Award NNH17AE86I. PC and JP were supported by the European Research Council Synergy grant ERC-2013-SyG-2013-610028 IMBALANCE-P. J. Pongratz was supported by the German Research Foundation?s Emmy Noether Program. MEBS acknowledges support from the Australian Research Council Centre of Excellence for Climate Extremes (CE170100023). JS acknowledges support from VR, KAW and Kempe foundations. CT was supported by a Lawrence Fellow award through Lawrence Livermore National Laboratory (LLNL) under contract DE-AC52-07NA27344 with the US Department of Energy and the LLNL-LDRD Program under Project no. 20-ERD-055. MST was supported by the US Department of Energy, Office of Science under contract number DE-AC02-05CH11231. ATT acknowledges funding from the USDA National Institute of Food and Agriculture, Agricultural and Food Research Initiative Competitive Programme grant no. 2018-67012-31496 and the University of California Laboratory Fees Research Program Award no. LFR-20-652467. SLV was supported by the US National Science Foundation Paleo Perspectives on Climate Change Program. PvM was supported by the US Geological Survey Ecosystems Mission Area. Government sponsorship is acknowledged. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US Government. Publisher Copyright: {\textcopyright} 2020 The Authors New Phytologist Foundation {\textcopyright} 2020 New Phytologist",

year = "2021",

month = mar,

doi = "10.1111/nph.16866",

language = "English (US)",

volume = "229",

pages = "2413--2445",

journal = "New Phytologist",

issn = "0028-646X",

publisher = "Wiley-Blackwell",

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}

TY - JOUR

T1 - Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO2

AU - Walker, Anthony P.

AU - De Kauwe, Martin G.

AU - Bastos, Ana

AU - Belmecheri, Soumaya

AU - Georgiou, Katerina

AU - Keeling, Ralph F.

AU - McMahon, Sean M.

AU - Medlyn, Belinda E.

AU - Moore, David J.P.

AU - Norby, Richard J.

AU - Zaehle, Sönke

AU - Anderson-Teixeira, Kristina J.

AU - Battipaglia, Giovanna

AU - Brienen, Roel J.W.

AU - Cabugao, Kristine G.

AU - Cailleret, Maxime

AU - Campbell, Elliott

AU - Canadell, Josep G.

AU - Ciais, Philippe

AU - Craig, Matthew E.

AU - Ellsworth, David S.

AU - Farquhar, Graham D.

AU - Fatichi, Simone

AU - Fisher, Joshua B.

AU - Frank, David C.

AU - Graven, Heather

AU - Gu, Lianhong

AU - Haverd, Vanessa

AU - Heilman, Kelly

AU - Heimann, Martin

AU - Hungate, Bruce A.

AU - Iversen, Colleen M.

AU - Joos, Fortunat

AU - Jiang, Mingkai

AU - Keenan, Trevor F.

AU - Knauer, Jürgen

AU - Körner, Christian

AU - Leshyk, Victor O.

AU - Leuzinger, Sebastian

AU - Liu, Yao

AU - MacBean, Natasha

AU - Malhi, Yadvinder

AU - McVicar, Tim R.

AU - Penuelas, Josep

AU - Pongratz, Julia

AU - Powell, A. Shafer

AU - Riutta, Terhi

AU - Sabot, Manon E.B.

AU - Schleucher, Juergen

AU - Sitch, Stephen

AU - Smith, William K.

AU - Sulman, Benjamin

AU - Taylor, Benton

AU - Terrer, César

AU - Torn, Margaret S.

AU - Treseder, Kathleen K.

AU - Trugman, Anna T.

AU - Trumbore, Susan E.

AU - van Mantgem, Phillip J.

AU - Voelker, Steve L.

AU - Whelan, Mary E.

AU - Zuidema, Pieter A.

N1 - Funding Information: This paper was outlined and informed by the ‘Integrating CO‐fertilization evidence streams and theory (ICOFEST)’ meeting held at Biosphere II in September 2018. The meeting was supported by the US Department of Energy Office of Science, Biological and Environmental Research through the Free Air CO Enrichment Model Data Synthesis (FACE‐MDS) project. ORNL is managed by UT‐Battelle, LLC, for the DOE under contract DE‐AC05‐00OR22725. MGDK acknowledges support from Australian Research Council (ARC) Discovery Grant (DP190101823). DJPM and WKS acknowledge support from NASA Terrestrial Ecosystems Grant 80NSSC19M0103. SZ received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 647204). KJAT acknowledges support from the Smithsonian's Forest Global Earth Observatory (ForestGEO). JBF contributed to this research at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration with support from the NASA IDS program. VH acknowledges support from the Earth Systems and Climate Change Hub, funded by the Australian Research Council. FJ acknowledges support by the Swiss NSF (no. 200020_172476). TFK was supported by the NASA Terrestrial Ecology Program IDS Award NNH17AE86I. PC and JP were supported by the European Research Council Synergy grant ERC‐2013‐SyG‐2013‐610028 IMBALANCE‐P. J. Pongratz was supported by the German Research Foundation’s Emmy Noether Program. MEBS acknowledges support from the Australian Research Council Centre of Excellence for Climate Extremes (CE170100023). JS acknowledges support from VR, KAW and Kempe foundations. CT was supported by a Lawrence Fellow award through Lawrence Livermore National Laboratory (LLNL) under contract DE‐AC52‐07NA27344 with the US Department of Energy and the LLNL‐LDRD Program under Project No. 20‐ERD‐055. MST was supported by the US Department of Energy, Office of Science under contract number DE‐AC02‐05CH11231. ATT acknowledges funding from the USDA National Institute of Food and Agriculture, Agricultural and Food Research Initiative Competitive Programme grant no. 2018‐67012‐31496 and the University of California Laboratory Fees Research Program Award No. LFR‐20‐652467. SLV was supported by the US National Science Foundation Paleo Perspectives on Climate Change Program. PvM was supported by the US Geological Survey Ecosystems Mission Area. Government sponsorship is acknowledged. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US Government. 2 2 Funding Information: This paper was outlined and informed by the ?Integrating CO2-fertilization evidence streams and theory (ICOFEST)? meeting held at Biosphere II in September 2018. The meeting was supported by the US Department of Energy Office of Science, Biological and Environmental Research through the Free Air CO2 Enrichment Model Data Synthesis (FACE-MDS) project. ORNL is managed by UT-Battelle, LLC, for the DOE under contract DE-AC05-00OR22725. MGDK acknowledges support from Australian Research Council (ARC) Discovery Grant (DP190101823). DJPM and WKS acknowledge support from NASA Terrestrial Ecosystems Grant 80NSSC19M0103. SZ received funding from the European Research Council (ERC) under the European Union?s Horizon 2020 research and innovation programme (grant agreement no. 647204). KJAT acknowledges support from the Smithsonian's Forest Global Earth Observatory (ForestGEO). JBF contributed to this research at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration with support from the NASA IDS program. VH acknowledges support from the Earth Systems and Climate Change Hub, funded by the Australian Research Council. FJ acknowledges support by the Swiss NSF (no. 200020_172476). TFK was supported by the NASA Terrestrial Ecology Program IDS Award NNH17AE86I. PC and JP were supported by the European Research Council Synergy grant ERC-2013-SyG-2013-610028 IMBALANCE-P. J. Pongratz was supported by the German Research Foundation?s Emmy Noether Program. MEBS acknowledges support from the Australian Research Council Centre of Excellence for Climate Extremes (CE170100023). JS acknowledges support from VR, KAW and Kempe foundations. CT was supported by a Lawrence Fellow award through Lawrence Livermore National Laboratory (LLNL) under contract DE-AC52-07NA27344 with the US Department of Energy and the LLNL-LDRD Program under Project no. 20-ERD-055. MST was supported by the US Department of Energy, Office of Science under contract number DE-AC02-05CH11231. ATT acknowledges funding from the USDA National Institute of Food and Agriculture, Agricultural and Food Research Initiative Competitive Programme grant no. 2018-67012-31496 and the University of California Laboratory Fees Research Program Award no. LFR-20-652467. SLV was supported by the US National Science Foundation Paleo Perspectives on Climate Change Program. PvM was supported by the US Geological Survey Ecosystems Mission Area. Government sponsorship is acknowledged. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US Government. Publisher Copyright: © 2020 The Authors New Phytologist Foundation © 2020 New Phytologist

PY - 2021/3

Y1 - 2021/3

N2 - Atmospheric carbon dioxide concentration ([CO2]) is increasing, which increases leaf-scale photosynthesis and intrinsic water-use efficiency. These direct responses have the potential to increase plant growth, vegetation biomass, and soil organic matter; transferring carbon from the atmosphere into terrestrial ecosystems (a carbon sink). A substantial global terrestrial carbon sink would slow the rate of [CO2] increase and thus climate change. However, ecosystem CO2 responses are complex or confounded by concurrent changes in multiple agents of global change and evidence for a [CO2]-driven terrestrial carbon sink can appear contradictory. Here we synthesize theory and broad, multidisciplinary evidence for the effects of increasing [CO2] (iCO2) on the global terrestrial carbon sink. Evidence suggests a substantial increase in global photosynthesis since pre-industrial times. Established theory, supported by experiments, indicates that iCO2 is likely responsible for about half of the increase. Global carbon budgeting, atmospheric data, and forest inventories indicate a historical carbon sink, and these apparent iCO2 responses are high in comparison to experiments and predictions from theory. Plant mortality and soil carbon iCO2 responses are highly uncertain. In conclusion, a range of evidence supports a positive terrestrial carbon sink in response to iCO2, albeit with uncertain magnitude and strong suggestion of a role for additional agents of global change.

AB - Atmospheric carbon dioxide concentration ([CO2]) is increasing, which increases leaf-scale photosynthesis and intrinsic water-use efficiency. These direct responses have the potential to increase plant growth, vegetation biomass, and soil organic matter; transferring carbon from the atmosphere into terrestrial ecosystems (a carbon sink). A substantial global terrestrial carbon sink would slow the rate of [CO2] increase and thus climate change. However, ecosystem CO2 responses are complex or confounded by concurrent changes in multiple agents of global change and evidence for a [CO2]-driven terrestrial carbon sink can appear contradictory. Here we synthesize theory and broad, multidisciplinary evidence for the effects of increasing [CO2] (iCO2) on the global terrestrial carbon sink. Evidence suggests a substantial increase in global photosynthesis since pre-industrial times. Established theory, supported by experiments, indicates that iCO2 is likely responsible for about half of the increase. Global carbon budgeting, atmospheric data, and forest inventories indicate a historical carbon sink, and these apparent iCO2 responses are high in comparison to experiments and predictions from theory. Plant mortality and soil carbon iCO2 responses are highly uncertain. In conclusion, a range of evidence supports a positive terrestrial carbon sink in response to iCO2, albeit with uncertain magnitude and strong suggestion of a role for additional agents of global change.

KW - CO fertilization

KW - CO-fertilization hypothesis

KW - beta factor

KW - carbon dioxide

KW - free-air CO enrichment (FACE)

KW - global carbon cycle

KW - land–atmosphere feedback

KW - terrestrial ecosystems

UR - http://www.scopus.com/inward/record.url?scp=85092938048&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85092938048&partnerID=8YFLogxK

U2 - 10.1111/nph.16866

DO - 10.1111/nph.16866

M3 - Review article

C2 - 32789857

AN - SCOPUS:85092938048

VL - 229

SP - 2413

EP - 2445

JO - New Phytologist

JF - New Phytologist

SN - 0028-646X

IS - 5

ER -