Plotted as anomalies, it's clear the top half of the ocean, the 0-to-2000 meter region, is gaining heat at an accelerating rate:
(ZJ = zettajoule = 1021 J.) Using the quadratic fit, the present rate of change of this region's OHC is 17 ZJ/yr, which is 1.0 W/m2.
A goodness-of-fit measure between the 2nd-order fit (i.e. with acceleration) and 1st-order fit (assuming no acceleration) continues to increase: