Year: 2023
Type: preprint
Abstract: The coastal ocean contributes to regulating atmospheric greenhouse gas concentrations by taking up carbon dioxide (CO2) and releasing nitrous oxide (N2O) and methane (CH4). Major advances have improved our understanding of the coastal air-sea exchanges of these three gasses since the first phase of the Regional Carbon Cycle Assessment and Processes (RECCAP in 2013), but a comprehensive view that integrates the three gasses at the global scale is still lacking. In this second phase (RECCAP2), we quantify global coastal ocean fluxes of CO2, N2O and CH4 using an ensemble of global gap-filled observation-based products and ocean biogeochemical models. The global coastal ocean is a net sink of CO2 in both observational products and models, but the magnitude of the median net global coastal uptake is ~60% larger in models (-0.72 vs. -0.44 PgC/yr, 1998-2018, coastal ocean area of 77 million km2). We attribute most of this model-product difference to the seasonality in sea surface CO2 partial pressure at mid- and high-latitudes, where models simulate stronger winter CO2 uptake. The global coastal ocean is a major source of N2O (+0.70 PgCO2-e /yr in observational product and +0.54 PgCO2-e /yr in model median) and of CH4 (+0.21 PgCO2-e /yr in observational product), which offsets a substantial proportion of the net radiative effect of coastal \co uptake (35-58% in CO2-equivalents). Data products and models need improvement to better resolve the spatio-temporal variability and long term trends in CO2, N2O and CH4 in the global coastal ocean.
Authors: Laure Resplandy, Allison Hogikyan, Hermann Werner Bange, Daniele Bianchi, Thomas S Weber, Wei-Jun Cai, Scott C. Doney, Katja Fennel, Marion Gehlen, Judith Hauck, Fabrice Lacroix, Peter Landschützer, Corinne Le Quéré, Jens Daniel Müller, Raymond Gabriel Najjar, Alizée Roobaert, Sarah Berthet, Laurent Bopp, Trang Thi-Tuyet Chau, Minhan Dai, Nicolas Gruber, Tatiana Ilyina, Annette Kock, Manfredi Manizza, Zouhair Lachkar, Goulven Gildas Laruelle, Enhui Liao, Ivan D. Lima, Cara Nissen, Christian Rödenbeck, Roland Séférian, Jörg Schwinger, Katsuya Toyama, Hiroyuki Tsujino, Pierre Regnier
Institutions: Princeton University, GEOMAR Helmholtz Centre for Ocean Research Kiel, University of California, Los Angeles, University of Rochester, University of Delaware, University of Virginia, Dalhousie University, Laboratoire des Sciences du Climat et de l'Environnement, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Max Planck Institute for Meteorology, University of East Anglia, ETH Zurich, Pennsylvania State University, Université Libre de Bruxelles, Centre National de Recherches Météorologiques, Laboratoire de Météorologie Dynamique, Institut Pierre-Simon Laplace, Xiamen University, Max Planck Society, Scripps Institution of Oceanography, New York University Abu Dhabi, Shanghai Jiao Tong University, Woods Hole Oceanographic Institution, University of Colorado Boulder, Max Planck Institute for Biogeochemistry, Centre National de la Recherche Scientifique, Météo-France, NORCE Research AS, Meteorological Research Institute, Japan Meteorological Business Support Center
Language: English
Subfield: Oceanography
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4366348184