Isolating the impacts of ocean heat uptake on global warming pattern and climate sensitivity

Under global warming, strong ocean heat uptake occurs over the subpolar North Atlantic and the Southern Ocean. Here we develop a modeling framework with a slab ocean-atmosphere coupled model to isolate the role of ocean heat uptake in the spatially varying global warming pattern and the temporally evolving climate sensitivity. We find that the extratropics-centered ocean heat uptake pattern acts to mute the polar amplification of CO2-induced warming in both hemispheres, especially over Antarctica, and also contributes significantly to the equatorially enhanced warming pattern in all three ocean basins. The spatially varying component of ocean heat uptake, although globally averaged to zero, can effectively rectify and lead to decreased global mean surface temperature of a comparable magnitude as the effect of global mean ocean heat uptake under transient climate change. Implications for understanding the transient nature of climate sensitivity will be discussed with a particular emphasis on the time-evolving ocean heat uptake.