Thermal Inertia

Thermal inertia is the resistance of a body to temperature change, set by its heat capacity and the rate it exchanges heat with surroundings. The ocean mixed layer, tens to over a hundred meters of well-stirred water, gives the climate system most of its thermal inertia: its large heat capacity makes sea-surface temperature lag atmospheric forcing by weeks to months and damps the diurnal and seasonal cycle. This lag delays the full warming response to greenhouse forcing, the committed warming still in the pipeline, and slows deep-ocean heat uptake over centuries.