Indeed ... it is generally believed most of sea level rise is due to thermal expansion ... and of course melting sea ice doesn't change sea level at all ...
The question is how far down the water column will the energy reach ... if it's only the top 100 meters, then there will be very little sea level rise ... whereas if these temperature increases reach all the way down to the ocean floor, we'll see tremendous sea level rise ... widespread convection is completely inhibited in our oceans ... we heat the water on top of the column, buoyancy forces keep it there ...
Energy can travel through water as radiation ... a little ways ... but not if there's biology in the way ... and oceans are full of biology, and have been for the past 4 billion years ...
That leaves conduction ... and that's real damn slow ...
One two three ... that's all the ways we have to change temperature ... at least using natural forces ... things like hockey sticks and hypercanes rely on magical forces, so maybe there's a different understanding from the Alchemists ...