Is altitude of everything decreasing due to sea level rise?

Question

We know that sea level is rising, though some people say climate change is fake.**Altitude** is defined as the height of something measured from sea level. Since sea level is increasing, and the heights of most things is not: **is the altitude of most things decreasing?**

Answer 1

No. Elevation is measured relative to an agreed vertical datum, not relative to the continuously changing ocean surface. That datum is designed to approximate mean sea level, but it is treated as a defined reference surface. Therefore, rising global mean sea level does not require all published elevations to be revised downward.

What does change is the object’s height relative to the nearby ocean surface. If sea level rises while the land remains fixed, the difference between the shoreline and the object becomes slightly smaller. In some places, relative sea level also changes because the land itself is rising or sinking due to tectonics, sediment compaction, groundwater withdrawal, or glacial isostatic adjustment.

So sea-level rise raises the reference water surface relative to the land; it does not normally lower the land itself.