High-resolution Insight Into the Role of the Southern Ocean in a High-Carbon Future

Efforts to determine the future uptake of carbon and heat by the Southern Ocean have been hampered by the enormous computational resources required to simulate ocean biogeochemistry in eddy-resolving coupled climate models. We compare the response of the Southern Ocean with respect to the uptake of heat and carbon to a doubling of atmospheric carbon dioxide in a suite of high to low resolution coupled climate model simulations developed and run at NOAA’s Geophysical Fluid Dynamics Laboratory. The three different configurations of the Geophysical Fluid Dynamics Laboratory (GFDL) coupled climate models include the eddy-resolving GFDL-CM2.6 with a nominal ocean resolution of 0.1° (4-10km); the eddy-permitting GFDL-CM2.5, with a nominal resolution of 0.25° (8-28km); and the standard resolution GFDL-CM2.1 (1°), in simulations in which the atmospheric CO₂ increases at 1% per year until doubling is achieved after 70 years. CM2.6 is coupled to a computationally-efficient biogeochemical module (Mini-BLING, Galbraith et al. 2010, 2015) with a reduced set of biogeochemical variables that allows an analysis of the uptake of carbon by the Southern Ocean, as well as the effects on nutrient storage and transport and potential acidification impacts. We evaluate this suite of simulations against the Earth System Model simulations generated in support of CMIP5, the results of the Southern Ocean State Estimate and against other observationally-based metrics.