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https://doi.org/10.5194/egusphere-2024-1735
https://doi.org/10.5194/egusphere-2024-1735
15 Jul 2024
 | 15 Jul 2024

Combined CO2 measurement record indicates decreased Amazon forest carbon uptake, offset by Savannah carbon release

Santiago Botía, Saqr Munassar, Thomas Koch, Danilo Custodio, Luana S. Basso, Shujiro Komiya, Jost V. Lavric, David Walter, Manuel Gloor, Giordane Martins, Stijn Naus, Gerbrand Koren, Ingrid Luijkx, Stijn Hantson, John B. Miller, Wouter Peters, Christian Rödenbeck, and Christoph Gerbig

Abstract. In tropical South America there has been substantial progress on atmospheric monitoring capacity, but the region still has a limited number of continental atmospheric stations relative to its large area, hindering net carbon flux estimates using atmospheric inversions. In this study, we use dry air CO2 mole fractions measured at the Amazon Tall Tower Observatory (ATTO) and airborne vertical CO2 profiles in an atmospheric inversion system to estimate the net carbon exchange in tropical South America. We focus on the biogeographic Amazon, and its neighboring Cerrado and Caatinga biomes. Considering all prior ensemble members, we estimate that the biogeographic Amazon was a net carbon sink with the sum of vegetation uptake, river outgassing and carbon release from fires at a median of -0.33 ± 0.33 PgC year-1. Using only process-based models as input in the inversion system the uptake is reduced to -0.24 ± 0.33 PgC year-1. The Cerrado and Caatinga biomes together represent a median carbon source of 0.31 ± 0.24 PgC year-1, with contributions from both vegetation carbon release and fires. Therefore, we estimate that the net carbon balance for tropical South America is close to neutral, but we note that the uncertainties straddle zero net exchange. In addition, we calculate the effect of systematic uncertainties in the inverse estimates by proposing a water-vapor correction to measured airborne CO2 profiles. Finally, to further reduce the uncertainty in regional carbon balance estimates in tropical South America, we call for an expansion of the atmospheric monitoring network on the continent, mainly in the Amazon-Andes foothills.

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Santiago Botía, Saqr Munassar, Thomas Koch, Danilo Custodio, Luana S. Basso, Shujiro Komiya, Jost V. Lavric, David Walter, Manuel Gloor, Giordane Martins, Stijn Naus, Gerbrand Koren, Ingrid Luijkx, Stijn Hantson, John B. Miller, Wouter Peters, Christian Rödenbeck, and Christoph Gerbig

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-1735', Anonymous Referee #1, 19 Sep 2024
  • RC2: 'Comment on egusphere-2024-1735', Ian Baker, 23 Sep 2024
Santiago Botía, Saqr Munassar, Thomas Koch, Danilo Custodio, Luana S. Basso, Shujiro Komiya, Jost V. Lavric, David Walter, Manuel Gloor, Giordane Martins, Stijn Naus, Gerbrand Koren, Ingrid Luijkx, Stijn Hantson, John B. Miller, Wouter Peters, Christian Rödenbeck, and Christoph Gerbig
Santiago Botía, Saqr Munassar, Thomas Koch, Danilo Custodio, Luana S. Basso, Shujiro Komiya, Jost V. Lavric, David Walter, Manuel Gloor, Giordane Martins, Stijn Naus, Gerbrand Koren, Ingrid Luijkx, Stijn Hantson, John B. Miller, Wouter Peters, Christian Rödenbeck, and Christoph Gerbig

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Short summary
This study uses CO2 data from the Amazon Tall Tower Observatory and airborne profiles to estimate net carbon exchange. We found that the biogeographic Amazon is a net carbon sink, while the Cerrado and Caatinga biomes are net carbon sources, resulting in an overall neutral balance. To further reduce the uncertainty in our estimates we call for an expansion of the monitoring capacity, especially in the Amazon-Andes foothills.