Sea levels are actually dropping, which is why the "warmers" have to lie about three island chains in the Pacific sinking.... never mind all three are on the "lip" of the tectonic formation known as the Pacific Ring of Fire...
Even as I read articles of how some islands expected to be essentially underwater now by some scientific estimations are actually increasing in size. Which actually has little or nothing to do with the levels of the ocean surrounding them.
But all our seas and oceans are interconnected, yes? So think of your average lake with all its eddies and inlets and perhaps an island or two. At any given time when there has been essentially no seismic activity or wind or precipitation the water level in the lake will be effectively the same all over the lake. Add major heating or major cold that water level will change by a very small amount. Fill some of the lake with thick ice and the water in any ice free areas will be higher. Melt the ice, and those higher water levels return to normal. But add wind and parts of the surface will be higher than other parts of the surface. Pour water into one end and it will for a short time be deeper than the other end.
The same things are happening all over the planet except on such a massively larger scale that it takes a lot longer for the sloshing or manipulation of the water levels to settle out evenly and perhaps they never can because there are always factors affecting sea levels. And it is much more difficult to measure and evaluate than the local lake or in our bathtubs.
But from NASA'S website, they probably are telling it like it is when they say:
. . .even with possible future accelerated discharge from the West Antarctic Ice Sheet, it highly unlikely that annual rates of sea level rise would exceed those of the major post-glacial meltwater pulse.
Yes sea levels are higher now than they were in the last century. And yes, sea levels will probably be higher in the 21st century than they are now. The fact is, the Earth warms after ever ice age until it reaches a tipping point and starts back into the next ice age which will occur.
So if human activity is warming the Earth, we might consider the possibility that could be a good thing in holding off the next ice age?