--- OA_place: publisher OA_type: free access _id: '22570' abstract: - lang: eng text: Atmospheric carbon dioxide concentration ([CO 2 ]) is increasing, which increases leaf-scalephotosynthesis and intrinsic water-use efficiency. These direct responses have the potential toincrease plant growth, vegetation biomass, and soil organic matter; transferring carbon from theatmosphere into terrestrial ecosystems (a carbon sink). A substantial global terrestrial carbon sinkwould slow the rate of [CO 2] increase and thus climate change. However, ecosystem CO2responses are complex or confounded by concurrent changes in multiple agents of global changeand evidence for a [CO 2]-driven terrestrial carbon sink can appear contradictory. Here wesynthesize theory and broad, multidisciplinary evidence for the effects of increasing [CO 2](iCO 2) on the global terrestrial carbon sink. Evidence suggests a substantial increase in globalphotosynthesis since pre-industrial times. Established theory, supported by experiments,indicates that iCO 2 is likely responsible for about half of the increase. Global carbon budgeting,atmospheric data, and forest inventories indicate a historical carbon sink, and these apparentiCO 2 responses are high in comparison to experiments and predictions from theory. Plantmortality and soil carbon iCO 2 responses are highly uncertain. In conclusion, a range of evidencesupports a positive terrestrial carbon sink in response to iCO2 , albeit with uncertain magnitudeand strong suggestion of a role for additional agents of global change. article_processing_charge: No article_type: original author: - first_name: Anthony P. full_name: Walker, Anthony P. last_name: Walker - first_name: Martin G. full_name: De Kauwe, Martin G. last_name: De Kauwe - first_name: Ana full_name: Bastos, Ana last_name: Bastos - first_name: Soumaya full_name: Belmecheri, Soumaya last_name: Belmecheri - first_name: Katerina full_name: Georgiou, Katerina last_name: Georgiou - first_name: Ralph F. full_name: Keeling, Ralph F. last_name: Keeling - first_name: Sean M. full_name: McMahon, Sean M. last_name: McMahon - first_name: Belinda E. full_name: Medlyn, Belinda E. last_name: Medlyn - first_name: David J. P. full_name: Moore, David J. P. last_name: Moore - first_name: Richard J. full_name: Norby, Richard J. last_name: Norby - first_name: Sönke full_name: Zaehle, Sönke last_name: Zaehle - first_name: Kristina J. full_name: Anderson‐Teixeira, Kristina J. last_name: Anderson‐Teixeira - first_name: Giovanna full_name: Battipaglia, Giovanna last_name: Battipaglia - first_name: Roel J. W. full_name: Brienen, Roel J. W. last_name: Brienen - first_name: Kristine G. full_name: Cabugao, Kristine G. last_name: Cabugao - first_name: Maxime full_name: Cailleret, Maxime last_name: Cailleret - first_name: Elliott full_name: Campbell, Elliott last_name: Campbell - first_name: Josep G. full_name: Canadell, Josep G. last_name: Canadell - first_name: Philippe full_name: Ciais, Philippe last_name: Ciais - first_name: Matthew E. full_name: Craig, Matthew E. last_name: Craig - first_name: David S. full_name: Ellsworth, David S. last_name: Ellsworth - first_name: Graham D. full_name: Farquhar, Graham D. last_name: Farquhar - first_name: Simone full_name: Fatichi, Simone id: cf8e546b-a9b0-11f0-a43b-aa89ed1b56d6 last_name: Fatichi - first_name: Joshua B. full_name: Fisher, Joshua B. last_name: Fisher - first_name: David C. full_name: Frank, David C. last_name: Frank - first_name: Heather full_name: Graven, Heather last_name: Graven - first_name: Lianhong full_name: Gu, Lianhong last_name: Gu - first_name: Vanessa full_name: Haverd, Vanessa last_name: Haverd - first_name: Kelly full_name: Heilman, Kelly last_name: Heilman - first_name: Martin full_name: Heimann, Martin last_name: Heimann - first_name: Bruce A. full_name: Hungate, Bruce A. last_name: Hungate - first_name: Colleen M. full_name: Iversen, Colleen M. last_name: Iversen - first_name: Fortunat full_name: Joos, Fortunat last_name: Joos - first_name: Mingkai full_name: Jiang, Mingkai last_name: Jiang - first_name: Trevor F. full_name: Keenan, Trevor F. last_name: Keenan - first_name: Jürgen full_name: Knauer, Jürgen last_name: Knauer - first_name: Christian full_name: Körner, Christian last_name: Körner - first_name: Victor O. full_name: Leshyk, Victor O. last_name: Leshyk - first_name: Sebastian full_name: Leuzinger, Sebastian last_name: Leuzinger - first_name: Yao full_name: Liu, Yao last_name: Liu - first_name: Natasha full_name: MacBean, Natasha last_name: MacBean - first_name: Yadvinder full_name: Malhi, Yadvinder last_name: Malhi - first_name: Tim R. full_name: McVicar, Tim R. last_name: McVicar - first_name: Josep full_name: Penuelas, Josep last_name: Penuelas - first_name: Julia full_name: Pongratz, Julia last_name: Pongratz - first_name: A. Shafer full_name: Powell, A. Shafer last_name: Powell - first_name: Terhi full_name: Riutta, Terhi last_name: Riutta - first_name: Manon E. B. full_name: Sabot, Manon E. B. last_name: Sabot - first_name: Juergen full_name: Schleucher, Juergen last_name: Schleucher - first_name: Stephen full_name: Sitch, Stephen last_name: Sitch - first_name: William K. full_name: Smith, William K. last_name: Smith - first_name: Benjamin full_name: Sulman, Benjamin last_name: Sulman - first_name: Benton full_name: Taylor, Benton last_name: Taylor - first_name: César full_name: Terrer, César last_name: Terrer - first_name: Margaret S. full_name: Torn, Margaret S. last_name: Torn - first_name: Kathleen K. full_name: Treseder, Kathleen K. last_name: Treseder - first_name: Anna T. full_name: Trugman, Anna T. last_name: Trugman - first_name: Susan E. full_name: Trumbore, Susan E. last_name: Trumbore - first_name: Phillip J. full_name: van Mantgem, Phillip J. last_name: van Mantgem - first_name: Steve L. full_name: Voelker, Steve L. last_name: Voelker - first_name: Mary E. full_name: Whelan, Mary E. last_name: Whelan - first_name: Pieter A. full_name: Zuidema, Pieter A. last_name: Zuidema citation: ama: Walker AP, De Kauwe MG, Bastos A, et al. Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO2. New Phytologist. 2021;229(5):2413-2445. doi:10.1111/nph.16866 apa: Walker, A. P., De Kauwe, M. G., Bastos, A., Belmecheri, S., Georgiou, K., Keeling, R. F., … Zuidema, P. A. (2021). Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO2. New Phytologist. Wiley. https://doi.org/10.1111/nph.16866 chicago: Walker, Anthony P., Martin G. De Kauwe, Ana Bastos, Soumaya Belmecheri, Katerina Georgiou, Ralph F. Keeling, Sean M. McMahon, et al. “Integrating the Evidence for a Terrestrial Carbon Sink Caused by Increasing Atmospheric CO2.” New Phytologist. Wiley, 2021. https://doi.org/10.1111/nph.16866. ieee: A. P. Walker et al., “Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO2,” New Phytologist, vol. 229, no. 5. Wiley, pp. 2413–2445, 2021. ista: 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. 229(5), 2413–2445. mla: Walker, Anthony P., et al. “Integrating the Evidence for a Terrestrial Carbon Sink Caused by Increasing Atmospheric CO2.” New Phytologist, vol. 229, no. 5, Wiley, 2021, pp. 2413–45, doi:10.1111/nph.16866. short: A.P. Walker, M.G. De Kauwe, A. Bastos, S. Belmecheri, K. Georgiou, R.F. Keeling, S.M. McMahon, B.E. Medlyn, D.J.P. Moore, R.J. Norby, S. Zaehle, K.J. Anderson‐Teixeira, G. Battipaglia, R.J.W. Brienen, K.G. Cabugao, M. Cailleret, E. Campbell, J.G. Canadell, P. Ciais, M.E. Craig, D.S. Ellsworth, G.D. Farquhar, S. Fatichi, J.B. Fisher, D.C. Frank, H. Graven, L. Gu, V. Haverd, K. Heilman, M. Heimann, B.A. Hungate, C.M. Iversen, F. Joos, M. Jiang, T.F. Keenan, J. Knauer, C. Körner, V.O. Leshyk, S. Leuzinger, Y. Liu, N. MacBean, Y. Malhi, T.R. McVicar, J. Penuelas, J. Pongratz, A.S. Powell, T. Riutta, M.E.B. Sabot, J. Schleucher, S. Sitch, W.K. Smith, B. Sulman, B. Taylor, C. Terrer, M.S. Torn, K.K. Treseder, A.T. Trugman, S.E. Trumbore, P.J. van Mantgem, S.L. Voelker, M.E. Whelan, P.A. Zuidema, New Phytologist 229 (2021) 2413–2445. das_tickbox: '1' date_created: 2026-07-27T12:30:24Z date_published: 2021-03-01T00:00:00Z date_updated: 2026-08-06T08:39:39Z day: '01' doi: 10.1111/nph.16866 extern: '1' external_id: pmid: - '32789857' intvolume: ' 229' issue: '5' keyword: - Beta factor - Carbon dioxide - CO2 fertilization - CO2-fertilization hypothesis - Free-air CO2 enrichment (FACE) - Global carbon cycle - Land–atmosphere feedback - Terrestrial ecosystems language: - iso: eng main_file_link: - open_access: '1' url: https://doi.org/10.1111/nph.16866 month: '03' oa: 1 oa_version: Published Version page: 2413-2445 pmid: 1 publication: New Phytologist publication_identifier: eissn: - 1469-8137 issn: - 0028-646X publication_status: published publisher: Wiley quality_controlled: '1' scopus_import: '1' status: public title: Integrating the evidence for a terrestrial carbon sink caused by increasing atmospheric CO2 type: journal_article user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd volume: 229 year: '2021' ... --- OA_place: publisher OA_type: free access _id: '22536' abstract: - lang: eng text: Increasing concentrations of atmospheric carbon dioxide are expected to affect carbon assimilation and evapotranspiration (ET), ultimately driving changes in plant growth, hydrology, and the global carbon balance. Direct leaf biochemical effects have been widely investigated, whereas indirect effects, although documented, elude explicit quantification in experiments. Here, we used a mechanistic model to investigate the relative contributions of direct (through carbon assimilation) and indirect (via soil moisture savings due to stomatal closure, and changes in leaf area index) effects of elevated CO2 across a variety of ecosystems. We specifically determined which ecosystems and climatic conditions maximize the indirect effects of elevated CO2. The simulations suggest that the indirect effects of elevated CO2 on net primary productivity are large and variable, ranging from less than 10% to more than 100% of the size of direct effects. For ET, indirect effects were, on average, 65% of the size of direct effects. Indirect effects tended to be considerably larger in water-limited ecosystems. As a consequence, the total CO2 effect had a significant, inverse relationship with the wetness index and was directly related to vapor pressure deficit. These results have major implications for our understanding of the CO2 response of ecosystems and for global projections of CO2 fertilization, because, although direct effects are typically understood and easily reproducible in models, simulations of indirect effects are far more challenging and difficult to constrain. Our findings also provide an explanation for the discrepancies between experiments in the total CO2 effect on net primary productivity. article_processing_charge: No article_type: original author: - first_name: Simone full_name: Fatichi, Simone id: cf8e546b-a9b0-11f0-a43b-aa89ed1b56d6 last_name: Fatichi - first_name: Sebastian full_name: Leuzinger, Sebastian last_name: Leuzinger - first_name: Athanasios full_name: Paschalis, Athanasios last_name: Paschalis - first_name: J. Adam full_name: Langley, J. Adam last_name: Langley - first_name: Alicia full_name: Donnellan Barraclough, Alicia last_name: Donnellan Barraclough - first_name: Mark J. full_name: Hovenden, Mark J. last_name: Hovenden citation: ama: Fatichi S, Leuzinger S, Paschalis A, Langley JA, Donnellan Barraclough A, Hovenden MJ. Partitioning direct and indirect effects reveals the response of water-limited ecosystems to elevated CO. Proceedings of the National Academy of Sciences. 2016;113(45):12757-12762. doi:10.1073/pnas.1605036113 apa: Fatichi, S., Leuzinger, S., Paschalis, A., Langley, J. A., Donnellan Barraclough, A., & Hovenden, M. J. (2016). Partitioning direct and indirect effects reveals the response of water-limited ecosystems to elevated CO. Proceedings of the National Academy of Sciences. National Academy of Sciences. https://doi.org/10.1073/pnas.1605036113 chicago: Fatichi, Simone, Sebastian Leuzinger, Athanasios Paschalis, J. Adam Langley, Alicia Donnellan Barraclough, and Mark J. Hovenden. “Partitioning Direct and Indirect Effects Reveals the Response of Water-Limited Ecosystems to Elevated CO.” Proceedings of the National Academy of Sciences. National Academy of Sciences, 2016. https://doi.org/10.1073/pnas.1605036113. ieee: S. Fatichi, S. Leuzinger, A. Paschalis, J. A. Langley, A. Donnellan Barraclough, and M. J. Hovenden, “Partitioning direct and indirect effects reveals the response of water-limited ecosystems to elevated CO,” Proceedings of the National Academy of Sciences, vol. 113, no. 45. National Academy of Sciences, pp. 12757–12762, 2016. ista: Fatichi S, Leuzinger S, Paschalis A, Langley JA, Donnellan Barraclough A, Hovenden MJ. 2016. Partitioning direct and indirect effects reveals the response of water-limited ecosystems to elevated CO. Proceedings of the National Academy of Sciences. 113(45), 12757–12762. mla: Fatichi, Simone, et al. “Partitioning Direct and Indirect Effects Reveals the Response of Water-Limited Ecosystems to Elevated CO.” Proceedings of the National Academy of Sciences, vol. 113, no. 45, National Academy of Sciences, 2016, pp. 12757–62, doi:10.1073/pnas.1605036113. short: S. Fatichi, S. Leuzinger, A. Paschalis, J.A. Langley, A. Donnellan Barraclough, M.J. Hovenden, Proceedings of the National Academy of Sciences 113 (2016) 12757–12762. das_tickbox: '1' date_created: 2026-07-27T12:30:24Z date_published: 2016-11-08T00:00:00Z date_updated: 2026-08-06T08:08:46Z day: '08' doi: 10.1073/pnas.1605036113 extern: '1' external_id: pmid: - '27791074' intvolume: ' 113' issue: '45' keyword: - carbon dioxide - modeling - FACE - soil moisture - evapotranspiration language: - iso: eng main_file_link: - open_access: '1' url: https://doi.org/10.1073/pnas.1605036113 month: '11' oa: 1 oa_version: Published Version page: 12757-12762 pmid: 1 publication: Proceedings of the National Academy of Sciences publication_identifier: eissn: - 1091-6490 issn: - 0027-8424 publication_status: published publisher: National Academy of Sciences quality_controlled: '1' scopus_import: '1' status: public title: Partitioning direct and indirect effects reveals the response of water-limited ecosystems to elevated CO type: journal_article user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd volume: 113 year: '2016' ...