Perhaps "trapped" is wrong - here are two eminent sources with alternative statements:
"extra heat being absorbed into the deep ocean"
"NOAA posts regularly updated measurements of the amount of heat stored in the bulk of the oceans."
And don't forget - The cold waters of Earth’s deep ocean have not warmed measurably since 2005, according to a new NASA study, leaving unsolved the mystery of why global warming appears to have slowed in recent years.
It doesn't change the basic aspects of thermodynamics. The volume of water in question will not change by what we would think of as significant temperatures when we consider it in terms of degrees Celsius or even in Kelvin. We need to consider the temperature in terms of the energy component. The easiest way is to consider the Joules required to raise 1ml of water by 1 degree Celsius, referred to as its specific temperature. That is according to SI Units is 4.186J/Ml at 1 atmosphere pressure. So consider the energy input required to raise the deep ocean temperature my a reliably measurable amount. Just because we cannot measure it with instruments we can calculate by the laws of thermal dynamics the energy amount being absorbed because we know the starting values of air temperature and the other variables such as pressure, water density, salinity etc. It becomes a very complex mathematical exercise, but it is just that a question of mathematics, not one of theory.
The complicating factor for those who really want to get into the maths is the fact that the specific temperature can vary depending on the pressure, density, and salinity. Further the energy state will influence the density and salinity. Those things then influence the currents which mix the layers and further complicate the calculation. All these things also in turn influence the absorptive rate which the oceans take up CO2 and other gases, which influences pH and in turn salinity and density.......... and so on and so on. It is no wonder the great mathematical minds prefer to hunt Dark Matter.
When you consider just this aspect of of climate change it should surprise anybody that the system will throw up unpredicted data, and people should not be expecting temperatures or change to move in a lineal fashion but in fit and starts that may be big moves or small. I have no doubt as well that there are significant variables that have not been accounted for, discovered or perhaps even thought relevant.
When considered in this light the "pause" if not significant, it might not even be a pause as such, just a change in energy absorption point. I don't know, and personally don't care, I have always approached this debate from the point of view that efficiency and less pollution is a good thing in and of itself, and if Australia took an early adoption of this position we would be better prepared for climate change AND economically come out in front at the same time.