Weak Northern and Strong Tropical Land Carbon Uptake from Vertical Profiles of Atmospheric CO ₂

Abstract

Measurements of midday vertical atmospheric CO 2 distributions reveal annual-mean vertical CO 2 gradients that are inconsistent with atmospheric models that estimate a large transfer of terrestrial carbon from tropical to northern latitudes. The three models that most closely reproduce the observed annual-mean vertical CO 2 gradients estimate weaker northern uptake of –1.5 petagrams of carbon per year (Pg C year –1 ) and weaker tropical emission of +0.1 Pg C year –1 compared with previous consensus estimates of –2.4 and +1.8 Pg C year –1 , respectively. This suggests that northern terrestrial uptake of industrial CO 2 emissions plays a smaller role than previously thought and that, after subtracting land-use emissions, tropical ecosystems may currently be strong sinks for CO 2 .

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Affiliated Institutions

• Roshydromet RU
• Sukachev Institute of Forest RU
• National Institute for Environmental Studies JP
• National Oceanic and Atmospheric Administration US
• Purdue University West Lafayette US
• Tohoku University JP
• NSF National Center for Atmospheric Research US
• Max Planck Institute for Biogeochemistry DE
• Colorado State University US
• Laboratoire des Sciences du Climat et de l'Environnement FR
• Commonwealth Scientific and Industrial Research Organisation AU

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