The observed evolution of oceanic pCO<sub>2</sub> and its drivers over the last two decades - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue Global Biogeochemical Cycles Année : 2012

The observed evolution of oceanic pCO2 and its drivers over the last two decades

Andrew Lenton
  • Fonction : Auteur
Nicolas Metzl
Taro Takahashi
  • Fonction : Auteur
Mareva Kuchinke
  • Fonction : Auteur
Richard J. Matear
  • Fonction : Auteur
Stewart C. Sutherland
  • Fonction : Auteur
Colm Sweeney
Bronte Tilbrook

Résumé

We use a database of more than 4.4 million observations of ocean pCO2 to investigate oceanic pCO2 growth rates. We use pCO2 measurements, with corresponding sea surface temperature and salinity measurements, to reconstruct alkalinity and dissolved inorganic carbon to understand what is driving these growth rates in different ocean regions. If the oceanic pCO2 growth rate is faster (slower) than the atmospheric CO2 growth rate, the region can be interpreted as having a decreasing (increasing) atmospheric CO2 uptake. Only the Western subpolar and subtropical North Pacific, and the Southern Ocean are found to have sufficient spatial and temporal observations to calculate the growth rates of oceanic pCO2 in different seasons. Based on these regions, we find the strength of the ocean carbon sink has declined over the last two decades due to a combination of regional drivers (physical and biological). In the subpolar North Pacific reduced atmospheric CO2 uptake in the summer is associated with changes in the biological production, while in the subtropical North Pacific enhanced uptake in winter is associated with enhanced biological production. In the Indian and Pacific sectors of the Southern Ocean a reduced winter atmospheric CO2 uptake is associated with a positive SAM response. Conversely in the more stratified Atlantic Ocean sector enhanced summer uptake is associated with increased biological production and reduced vertical supply. We are not able to separate climate variability and change as the calculated growth rates are at the limit of detection and are associated with large uncertainties. Ongoing sustained observations of global oceanic pCO2 and its drivers, including dissolved inorganic carbon and alkalinity, are key to detecting and understanding how the ocean carbon sink will evolve in future and what processes are driving this change.
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hal-00753350 , version 1 (04-11-2021)

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Andrew Lenton, Nicolas Metzl, Taro Takahashi, Mareva Kuchinke, Richard J. Matear, et al.. The observed evolution of oceanic pCO2 and its drivers over the last two decades. Global Biogeochemical Cycles, 2012, 26, pp.GB2021. ⟨10.1029/2011GB004095⟩. ⟨hal-00753350⟩
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