If you look on any topographical map, you’ll notice that elevations are reported in height above (or occasionally, below) sea level. Pilots often report altitudes in AMSL, or Above Mean Sea Level.

Coastal areas are particularly vulnerable to the anticipated sea level increases ... as indicated by the red zones on the map above. Meanwhile, parts of Texas, Florida, and California are all ...

This map extract shows exact heights by a black dot with a number next to it. The number is the height above sea level in metres. The blue triangle represents a triangulation pillar; the networks ...