Global riverine land-to-ocean carbon export constrained by observations and multi-model assessment

Maodian Liu
Peter A. Raymond
Ronny Lauerwald
Qianru Zhang
Gerrit Trapp-Müller
Kay L. Davis
Nils Moosdorf
Changhao Xiao
Jack J. Middelburg
Alexander F. Bouwman
Athur A. W. Beusen
Changhui Peng
Fabrice Lacroix
Hanqin Tian
Junjie Wang
Mingxu Li
Qiuan Zhu
Sagy Cohen
Wim J. van Hoek
Ya Li
Yangmingkai Li
Yuanzhi Yao
Pierre Regnier

Departments

Abstract

Rivers are a key component of the global carbon cycle. They receive vast quantities of terrestrial carbon, of which a large fraction is ultimately exported to the coastal ocean. Our review of previously published assessments reveals that substantial uncertainties remain with regard to the spatial distribution and speciation of the carbon export. Accurate quantification of the relative contributions of dissolved, particulate, organic and inorganic carbon to the total amounts is, however, of crucial importance for the coupling between the terrestrial and marine carbon cycles. Breaking down existing spatially explicit assessments over large river basins, we find a disagreement in flux estimates that exceeds two orders of magnitude for more than half of the basins. Using machine-learning techniques in combination with a multi-model ensemble and an updated database of observations, we overcome the inconsistencies in existing assessments and narrow down uncertainties in riverine carbon exports. Our revised assessment yields a global riverine export of 1.02 ± 0.22 (2σ) PgC yr−1. This carbon flux is partitioned into 0.52 ± 0.17, 0.30 ± 0.14, 0.18 ± 0.04 and 0.03 ± 0.02 PgC yr−1 of dissolved inorganic, dissolved organic, particulate organic and particulate inorganic carbon, respectively. We estimate the carbon contribution through groundwater export to be minor (0.016 PgC yr−1). Our assessment suggests an underestimation of the land-to-ocean carbon flux by 0.24 PgC yr−1 by the Intergovernmental Panel on Climate Change (IPCC) and calls for a revision of the oceanic carbon budget.

DOI: 10.1038/s41561-024-01524-z

Cite this activity

Liu M., Raymond P.A., Lauerwald R., Zhang Q., Trapp-Müller G., Davis K.L., Moosdorf N., Xiao C., Middelburg J.J., Bouwman A.F., Beusen A.A.W., Peng C., Lacroix F., Tian H., Wang J., Li M., Zhu Q., Cohen S., van Hoek W.J., Li Y., Li Y., Yao Y. and Regnier P. (2024) Global riverine land-to-ocean carbon export constrained by observations and multi-model assessment. Nature Geoscience 17: 896-904. 10.1038/s41561-024-01524-z

@article{Liu2024,
Title = {Global riverine land-to-ocean carbon export constrained by observations and multi-model assessment},
Author = {Liu, Maodian and Raymond, Peter A. and Lauerwald, Ronny and Zhang, Qianru and Trapp-Müller, Gerrit and Davis, Kay L. and Moosdorf, Nils and Xiao, Changhao and Middelburg, Jack J. and Bouwman, Alexander F. and Beusen, Athur A. W. and Peng, Changhui and Lacroix, Fabrice and Tian, Hanqin and Wang, Junjie and Li, Mingxu and Zhu, Qiuan and Cohen, Sagy and van Hoek, Wim J. and Li, Ya and Li, Yangmingkai and Yao, Yuanzhi and Regnier, Pierre},
Editor = {},
Journal = {Nature Geoscience},
Year = {2024},
Pages = {896-904},
Volume = {17},
Doi = {10.1038/s41561-024-01524-z},
Abstract = {Rivers are a key component of the global carbon cycle. They receive vast quantities of terrestrial carbon, of which a large fraction is ultimately exported to the coastal ocean. Our review of previously published assessments reveals that substantial uncertainties remain with regard to the spatial distribution and speciation of the carbon export. Accurate quantification of the relative contributions of dissolved, particulate, organic and inorganic carbon to the total amounts is, however, of crucial importance for the coupling between the terrestrial and marine carbon cycles. Breaking down existing spatially explicit assessments over large river basins, we find a disagreement in flux estimates that exceeds two orders of magnitude for more than half of the basins. Using machine-learning techniques in combination with a multi-model ensemble and an updated database of observations, we overcome the inconsistencies in existing assessments and narrow down uncertainties in riverine carbon exports. Our revised assessment yields a global riverine export of 1.02 ± 0.22 (2σ) PgC yr−1. This carbon flux is partitioned into 0.52 ± 0.17, 0.30 ± 0.14, 0.18 ± 0.04 and 0.03 ± 0.02 PgC yr−1 of dissolved inorganic, dissolved organic, particulate organic and particulate inorganic carbon, respectively. We estimate the carbon contribution through groundwater export to be minor (0.016 PgC yr−1). Our assessment suggests an underestimation of the land-to-ocean carbon flux by 0.24 PgC yr−1 by the Intergovernmental Panel on Climate Change (IPCC) and calls for a revision of the oceanic carbon budget.},
}

TY - JOUR
AU - Liu, Maodian
AU - Raymond, Peter A.
AU - Lauerwald, Ronny
AU - Zhang, Qianru
AU - Trapp-Müller, Gerrit
AU - Davis, Kay L.
AU - Moosdorf, Nils
AU - Xiao, Changhao
AU - Middelburg, Jack J.
AU - Bouwman, Alexander F.
AU - Beusen, Athur A. W.
AU - Peng, Changhui
AU - Lacroix, Fabrice
AU - Tian, Hanqin
AU - Wang, Junjie
AU - Li, Mingxu
AU - Zhu, Qiuan
AU - Cohen, Sagy
AU - van Hoek, Wim J.
AU - Li, Ya
AU - Li, Yangmingkai
AU - Yao, Yuanzhi
AU - Regnier, Pierre
TI - Global riverine land-to-ocean carbon export constrained by observations and multi-model assessment
T2 - Nature Geoscience
PY - 2024
SP - 896-904
VL - 17
DO - 10.1038/s41561-024-01524-z
AB - Rivers are a key component of the global carbon cycle. They receive vast quantities of terrestrial carbon, of which a large fraction is ultimately exported to the coastal ocean. Our review of previously published assessments reveals that substantial uncertainties remain with regard to the spatial distribution and speciation of the carbon export. Accurate quantification of the relative contributions of dissolved, particulate, organic and inorganic carbon to the total amounts is, however, of crucial importance for the coupling between the terrestrial and marine carbon cycles. Breaking down existing spatially explicit assessments over large river basins, we find a disagreement in flux estimates that exceeds two orders of magnitude for more than half of the basins. Using machine-learning techniques in combination with a multi-model ensemble and an updated database of observations, we overcome the inconsistencies in existing assessments and narrow down uncertainties in riverine carbon exports. Our revised assessment yields a global riverine export of 1.02 ± 0.22 (2σ) PgC yr−1. This carbon flux is partitioned into 0.52 ± 0.17, 0.30 ± 0.14, 0.18 ± 0.04 and 0.03 ± 0.02 PgC yr−1 of dissolved inorganic, dissolved organic, particulate organic and particulate inorganic carbon, respectively. We estimate the carbon contribution through groundwater export to be minor (0.016 PgC yr−1). Our assessment suggests an underestimation of the land-to-ocean carbon flux by 0.24 PgC yr−1 by the Intergovernmental Panel on Climate Change (IPCC) and calls for a revision of the oceanic carbon budget.
ER -