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Physically driven patchy O 2 changes in the North Atlantic Ocean simulated by the CMIP5 Earth system models
Author(s) -
Tagklis F.,
Bracco A.,
Ito T.
Publication year - 2017
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1002/2016gb005617
Subject(s) - coupled model intercomparison project , photic zone , advection , oceanography , environmental science , north atlantic deep water , ocean current , nutrient , gulf stream , climatology , convection , new production , thermohaline circulation , water mass , current (fluid) , atmospheric sciences , climate change , geology , climate model , phytoplankton , chemistry , meteorology , geography , organic chemistry , physics , thermodynamics
The subpolar North Atlantic is a key region for the oceanic uptake of heat, oxygen, and carbon dioxide. Centennial oxygen (O 2 ) changes are investigated in the upper 700 m of the North Atlantic Ocean using a subset of Earth system models (ESMs) included in the Coupled Model Intercomparison Project phase 5. The climatological distributions of dissolved O 2 averaged for the recent past period (1975–2005) are generally well captured, although the convective activity differs among the models in space and strength, and most models show a cold bias south of Greenland. By the end of the twenty‐first century, all models predict an increase in depth‐integrated temperature of 2–3°C, resultant solubility decrease, weakened vertical mass transport, decreased nutrient supply into the euphotic layer, and weakened export production. Despite an overall tendency of the North Atlantic to lose oxygen, patchy regions of O 2 increase are observed due to the weakening of the North Atlantic Current (NAC) causing a regional solubility increase (the warming hole effect) and a decrease in the advection of subtropical, low‐O 2 waters into the subpolar regions (the nutrient stream effect). Additionally, a shift in the NAC position contributes to localized O 2 changes near the boundaries of water masses. The net O 2 change reflects the combination of multiple factors leading to highly heterogeneous and model‐dependent patterns. Our results imply that changes in the strength and position of the NAC will likely play crucial roles in setting the pattern of O 2 changes in future projections.