Rodgers K. B., Ishii M., Frolicher T. L., Schlunegger S., Aumont Olivier, Toyama K., Slater R. D. (2020). Coupling of surface ocean heat and carbon perturbations over the subtropical cells under twenty-first century climate change. Journal of Climate, 33 (23), p. 10321-10338. ISSN 0894-8755.
Titre du document
Coupling of surface ocean heat and carbon perturbations over the subtropical cells under twenty-first century climate change
Rodgers K. B., Ishii M., Frolicher T. L., Schlunegger S., Aumont Olivier, Toyama K., Slater R. D.
Source
Journal of Climate, 2020,
33 (23), p. 10321-10338 ISSN 0894-8755
It is well established that the ocean plays an important role in absorbing anthropogenic carbon C-ant from the atmosphere. Under global warming, Earth system model simulations and theoretical arguments indicate that the capacity of the ocean to absorb C-ant will be reduced, with this constituting a positive carbon-climate feedback. Here we apply a suite of sensitivity simulations with a comprehensive Earth system model to demonstrate that the surface waters of the shallow overturning structures (spanning 45 degrees S-45 degrees N) sustain nearly half of the global ocean carbon-climate feedback. The main results reveal a feedback that is initially triggered by warming but that amplifies over time as C-ant invasion enhances the sensitivity of surface pCO(2) to further warming, particularly in the warmer season. Importantly, this "heat-carbon feedback' mechanism is distinct from (and significantly weaker than) what one would expect from temperature-controlled solubility perturbations to pCO(2) alone. It finds independent confirmation in an additional perturbation experiment with the same Earth system model. There mechanism denial is applied by disallowing the secular trend in the physical state of the ocean under climate change, while simultaneously allowing the effects of heating to impact sea surface pCO(2) and thereby CO2 uptake. Reemergence of C-ant along the equator within the shallow over-turning circulation plays an important role in the heat-carbon feedback, with the decadal renewal time scale for thermocline waters modulating the feedback response. The results here for 45 degrees S-45 degrees N stand in contrast to what is found in the high latitudes, where a clear signature of a broader range of driving mechanisms is present.
Plan de classement
Sciences du milieu [021]
;
Limnologie physique / Océanographie physique [032]
